UNIVERSITY OF CAMBRIDGE Electrical Safety: Policy and Procedures

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GK Batchelor Laboratory Department of Applied Mathematics and Theoretical Physics

UNIVERSITY OF CAMBRIDGE

Electrical Safety: Policy and Procedures

Contents 1 Scope .......................................................................................................................... 5 2 Use of Equipment....................................................................................................... 5

2.1 Policy................................................................................................................... 5 2.1.1 Offices .......................................................................................................... 5 2.1.2 Laboratory .................................................................................................... 5 2.1.3 Laptops ......................................................................................................... 5 2.1.4 Home office.................................................................................................. 6

2.2 Testing................................................................................................................. 6 2.3 Auditing............................................................................................................... 7 2.4 Rig Risk Assessment ........................................................................................... 7 2.5 Elemental Risk Assessment ................................................................................ 8 2.6 Operating Procedures .......................................................................................... 8 2.7 Standard Procedures............................................................................................ 9

2.7.1 Positioning of Equipment............................................................................. 9 2.7.2 RCD Protection ............................................................................................ 9 2.7.3 Switching...................................................................................................... 9 2.7.4 Extension leads and plug boards ................................................................ 10 2.7.5 Earth bonding ............................................................................................. 10 2.7.6 Submersible equipment .............................................................................. 10

2.8 Faults ................................................................................................................. 11 2.9 Disposal ............................................................................................................. 11 2.10 People .............................................................................................................. 11

2.10.1 User .......................................................................................................... 11 2.10.2 Electrical Safety Assessor ........................................................................ 11

3 Tests ......................................................................................................................... 11 3.1 Brand New Equipment ...................................................................................... 11 3.2 Equipment from Other Sources......................................................................... 12 3.3 Standard Tests ................................................................................................... 12

3.3.1 Cable damage ............................................................................................. 12 3.3.2 Casing damage and condition .................................................................... 12 3.3.3 Fuse rating.................................................................................................. 12 3.3.4 Earth bond .................................................................................................. 12 3.3.5 Insulation.................................................................................................... 13 3.3.6 Operational ................................................................................................. 13 3.3.7 Earth leakage.............................................................................................. 13

3.4 Flash Tests......................................................................................................... 13 3.5 Supplementary Tests ......................................................................................... 13

4 Documentation ......................................................................................................... 14

Electrical testing: Intervals and procedures DAMTP

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4.1 Record Sheet ..................................................................................................... 14 4.2 Test Sticker........................................................................................................ 14 4.3 Database ............................................................................................................ 14

5 Office Equipment ..................................................................................................... 15 5.1 Office Appliances.............................................................................................. 15

5.1.1 Desk lamps ................................................................................................. 15 5.1.2 Fans ............................................................................................................ 15 5.1.3 Heaters........................................................................................................ 15

5.2 Kitche and Cleaning .......................................................................................... 16 5.2.1 Kettles......................................................................................................... 16 5.2.2 Microwaves ................................................................................................ 16 5.2.3 Vacuum cleaners ........................................................................................ 16

5.3 IT Equipment..................................................................................................... 17 5.3.1 Computers .................................................................................................. 17 5.3.2 Computer monitors..................................................................................... 17 5.3.3 Laptops ....................................................................................................... 18 5.3.4 Printers ....................................................................................................... 18 5.3.5 Data hubs.................................................................................................... 18

5.4 Communication Equipment............................................................................... 19 5.4.1 Answerphones and dictation machines ...................................................... 19 5.4.2 Fax machines.............................................................................................. 19

5.5 Reproduction Equipment................................................................................... 19 5.5.1 Photocopiers ............................................................................................... 19 5.5.2 Binders ....................................................................................................... 19

5.6 Projection Equipment ........................................................................................ 20 5.6.1 Slide projectors........................................................................................... 20 5.6.2 Overhead projectors ................................................................................... 20 5.6.3 Data projectors ........................................................................................... 20 Video tape recorders............................................................................................ 21

6 General Equipment................................................................................................... 21 6.1 Catering Equipment........................................................................................... 21 6.2 Plant................................................................................................................... 21 6.3 Lighting and Sockets ......................................................................................... 21

7 Laboratory Equipment.............................................................................................. 21 7.1 Office Appliances.............................................................................................. 21

7.1.1 Desk lamps ................................................................................................. 21 7.1.2 Fans ............................................................................................................ 22 7.1.3 Vacuum cleaners ........................................................................................ 22

7.2 Laboratory Appliances ...................................................................................... 22 7.2.1 Densitometer .............................................................................................. 22 7.2.2 Refrigerator ................................................................................................ 23 7.2.3 Freezer........................................................................................................ 23

7.3 IT Equipment..................................................................................................... 23 7.3.1 Computers .................................................................................................. 23 7.3.2 Computer monitors..................................................................................... 24 7.3.3 Printers ....................................................................................................... 24 7.3.4 Data hubs.................................................................................................... 24 7.3.5 Portable equipment..................................................................................... 25

7.4 Video Equipment and Cameras......................................................................... 25 7.4.1 Video tape recorders................................................................................... 25


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7.4.2 Video monitors........................................................................................... 25 7.4.3 Video timers ............................................................................................... 26 7.4.4 High-speed cine camera ............................................................................. 26 7.4.5 Video cameras ............................................................................................ 26 7.4.6 Camera power supplies .............................................................................. 27

7.5 Light Sources..................................................................................................... 27 7.5.1 Projectors.................................................................................................... 27 7.5.2 Photographic lamps.................................................................................... 28 7.5.3 Turntable lamps.......................................................................................... 28 7.5.4 Fluorescent lamps....................................................................................... 29 7.5.5 Light boxes................................................................................................. 30 7.5.6 Arc lamps ................................................................................................... 30 7.5.7 Strobe lights ............................................................................................... 31

7.6 Lasers ................................................................................................................ 31 7.7 Power Supplies .................................................................................................. 31

7.7.1 Bench supplies ........................................................................................... 31 7.7.2 Plug-in adapters.......................................................................................... 32 7.7.3 High voltage supplies ................................................................................. 32

7.8 Laboratory Instrumentation............................................................................... 33 7.8.1 Amplifiers................................................................................................... 33 7.8.2 Bridge circuits ............................................................................................ 34 7.8.3 Multimeters ................................................................................................ 34 7.8.4 Oscilloscopes.............................................................................................. 34 7.8.5 High voltage equipment ............................................................................. 35

7.9 Motors and Controllers...................................................................................... 36 7.9.1 Servo motor controllers.............................................................................. 36 7.9.2 Servo motors .............................................................................................. 36 7.9.3 AC motors .................................................................................................. 36

7.10 Pumps .............................................................................................................. 37 7.10.1 Integrated pumps ...................................................................................... 37 7.10.2 Peristaltic pumps ...................................................................................... 37 7.10.3 Submersible pumps .................................................................................. 38 7.10.4 Vacuum pumps......................................................................................... 38 7.10.5 Double-bucket pumps .............................................................................. 38 7.10.6 Variable speed pumps .............................................................................. 39

7.11 Turntables........................................................................................................ 39 7.11.1 Turntables................................................................................................. 39

7.12 Laboratory Equipment..................................................................................... 40 7.12.1 Heat baths................................................................................................. 40 7.12.2 Stirrers ...................................................................................................... 40 7.12.3 Scales........................................................................................................ 41 7.12.4 Immersion heaters .................................................................................... 41

7.13 Frameworks and Tanks ................................................................................... 41 7.13.1 Metalwork ................................................................................................ 41

7.14 Power Cords .................................................................................................... 42 7.14.1 Standard cords (IEC)................................................................................ 42 7.14.2 Non-standard cords .................................................................................. 43 7.14.3 Cords with RCD....................................................................................... 43

7.15 Plug-boards and Extension Leads ................................................................... 43 7.15.1 Plug-boards............................................................................................... 43


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7.15.2 Integrated plug-boards.............................................................................. 44 7.15.3 Extension Leads ....................................................................................... 44

7.16 RCDs ............................................................................................................... 45 7.16.1 RCD adapters ........................................................................................... 45 7.16.2 RCD plugs ................................................................................................ 45 7.16.3 RCD sockets............................................................................................. 45

7.17 Fixed Installations ........................................................................................... 45 7.17.1 Hand driers ............................................................................................... 45 7.17.2 Heaters...................................................................................................... 46

7.18 Three-phase Installations................................................................................. 46 7.18.1 Wind tunnels ............................................................................................ 46 7.18.2 Flumes ...................................................................................................... 46 7.18.3 Sump pump .............................................................................................. 46 7.18.4 Ventilation equipment .............................................................................. 47

8 Workshop ................................................................................................................. 47 8.1 Hand Tools ........................................................................................................ 47

8.1.1 Drills........................................................................................................... 47 8.1.2 Grinders...................................................................................................... 47 8.1.3 Saws ........................................................................................................... 48 8.1.4 Routers ....................................................................................................... 48 8.1.5 Heat guns.................................................................................................... 49 8.1.6 Soldering irons ........................................................................................... 49

8.2 Fixed Tools........................................................................................................ 49 Three Years ......................................................................................................... 49

8.3 Three-phase Installations................................................................................... 50 8.3.1 Milling machines........................................................................................ 50 8.3.2 Lathes ......................................................................................................... 50 8.3.3 Drilling machines ....................................................................................... 50 8.3.4 Compressor ................................................................................................ 50 8.3.5 Abrasion tools ............................................................................................ 51


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1 Scope This document outlines the various procedures, responsibilities, and risks associated with the use of mains-operated electrical equipment in the Fluid Dynamics Laboratory. The document provides guidance for the development of Risk Assessments, and describes the various test procedures and hazards associated with the main classes of equipment used in the Laboratory and Workshop.

NOTE: A replacement for this document is under preparation. A draft of the new CMS Site Policy may be found at http://www.damtp.cam.ac.uk/lab/safety/ElectricalDraftPolicy.pdf

2 Use of Equipment 2.1 POLICY

2.1.1 Offices No mains-operated electrical or electronic equipment may be used unless it has a valid test sticker issued by the Department. Test stickers from other sources are not acceptable alternatives. This requirement applies to all office equipment and domestic appliances, including computers and even if they are brand new. Any equipment that has been modified or is not standard equipment must be subject to the procedures and standards outlined for laboratory equipment.

The user must be familiar with the manufacturer’s instructions for the equipment and use it in accordance with these.

Failure to observe these procedures may result in sanctions or disciplinary action against the offender.

2.1.2 Laboratory No mains-operated electrical or electronic equipment may be used unless it has a valid test sticker issued by the Department and a Risk Assessment has been carried out. Test stickers from other sources are not acceptable alternatives, and stickers are required even for brand new equipment. The user must have read and be familiar with the Operational Procedures for the equipment. The user must also be familiar with and adhere to the general guidance and procedures given in the Laboratory Safety Guidelines and the specific procedures outlined below.

Failure to observe these procedures may result in sanctions or disciplinary action against the offender.

2.1.3 Laptops All laptops purchased or owned by the Department must be tested in accordance with this policy, even if the laptop is never used within the Department itself. Testing should include inspection of any multi-standard mains adapter that may be used with the laptop.

When outside the Department, users should only connect to the mains if they are confident that the electrical outlet is safe and that their laptop is not damaged.

http://www.damtp.cam.ac.uk/lab/safety/ElectricalDraftPolicy.pdf


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Visitors from outside the Department are requested not to connect their laptops unless they have been tested to a level comparable to that outlined in this document. The Department is happy to test laptops for long-term visitors. It is recommended that short-term visitors run their laptops from batteries. The Department does not condone the use of laptops that have not been tested and cannot be held liable for any injury, damage or other consequence of failing to observe this guideline.

2.1.4 Home office Some members of staff have equipment (primarily IT equipment) in their own homes where this equipment is purchased out of departmental or research funds. The responsibility for ensuring that this equipment is tested regularly (typically every three years) falls solely on the user of such equipment. The Department will test such equipment if the user brings it into the Department for testing. The Department will also test other equipment that is used predominantly for work at home, even when it is not owned by the Department, provided it is brought into the Department for testing.

Users should adhere to the same level of standards in both the home office and Departmental contexts. This includes but is not limited to Electrical Safety and the University’s guidelines for the use of VDU screen equipment.

The Department cannot be held responsible for loss or injury resulting from failure to adhere to this guideline or from failure to ensure the equipment is tested regularly.

2.2 TESTING Prior to 2000, the test stickers on items of equipment indicated only the date the equipment was last tested. From July 2000 onwards, the stickers indicate both the date tested, and the date the next test is due. With the older type of stickers, the user should seek verification that the equipment is still safe to use for any equipment where the date is more than two years before the present. For the newer style of sticker, equipment must not be used beyond the ‘next test due’ date.

For equipment where the mains power cable is not integral, both the cable and the equipment itself should have a valid test sticker.

Brand new items, and equipment sourced from elsewhere must also be issued with test stickers. The equipment must not be used until this has been completed. The level of testing required for this is detailed elsewhere in this document.

In the Risk Assessment for a laboratory experiment, the user must list all electrical equipment and record the ‘next test due’ date for each item. It is the responsibility of the user to react accordingly when this due date is approaching. It is recommended that a re-test is requested four weeks before the due date. Note that failure to request testing at least three weeks in advance of the due date may lead to delays in the experimental programme while awaiting for a test to be undertaken.

The user should also complete a visual inspection of all equipment on a regular basis. Any defective, damaged or otherwise unsafe equipment should be disconnected immediately and the reason for the disconnection indicated on the


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equipment. Notices for indicating faults are available from the Electronics Technician. The defect should also be reported to the Electronics Technician.

Not all equipment will be subject automatically to regular testing. The testing of items that have not been used for a long time, or are only used infrequently, may be allowed to lapse to avoid unnecessary testing. It is the responsibility of the user to check that the testing is up to date before connecting the equipment.

2.3 AUDITING All equipment in active use will be audited on a regular basis. For equipment in the Laboratory and Workshop, this auditing will occur every six months. For equipment in the offices, this auditing will occur annually.

Typically, an audit will involve inspecting a subset of equipment to ensure the relevant procedures have been adhered to.

During an audit (or at any other time), any equipment found not to have a valid test sticker, found not to meet standard practices, or found to have an obvious defect, must be disconnected immediately. Such equipment must not be reconnected until it has been tested and any problems have been rectified. The Safety Officer must be informed of all such equipment. In most cases, failure during an audit will trigger a more detailed examination of any associated equipment.

2.4 RIG RISK ASSESSMENT A Risk Assessment must always be undertaken for an experimental rig. This Rig Risk Assessment is normally developed by the user or potential user of the rig, often in consultation with previous users or other Laboratory personnel. The Rig Risk Assessment may draw upon details contained in the Risk Assessment for other similar rigs; when this occurs, this link should be spelt out explicitly in the assessment.

The scope of this Rig Risk Assessment is not limited to electrical equipment, but must include the full range of mechanical, chemical, light and other potential hazards.

This Rig Risk Assessment must list each of the items of electrical equipment used in the rig, and the date at which they are next due to be tested must be recorded.

The Rig Risk Assessment should highlight all potential risks, safe operating procedures, safe methods in which the rig may be shutdown, and the risk posed through any equipment connected via signal or data cables. The Rig Risk Assessment must be completed before the experimental rig is first used, and reviewed or revised whenever there is any material change in the set-up. The adequacy of the Rig Risk Assessment and the overall safety of the experimental rig must be reviewed by an Electrical Safety Assessor prior to any work being undertaken.

The Rig Risk Assessment must also contain a copy of or explicit reference to the Risk Assessment for any individual component that requires a separate Elemental Risk Assessment, and any limitations of use or recommended practice contained in such a separate assessment must be observed.


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Such separate Elemental Risk Assessments are required for all discrete electrical components that are custom-built, modified in any way, or used in a manner or for a purpose differing from that envisaged by the manufacturer.

All queries concerning electrical safety should be directed to the Director of the Laboratory or the Electronics Technician. The Electronics Technician will normally undertake any electrical tests required.

2.5 ELEMENTAL RISK ASSESSMENT An Elemental Risk Assessment should be completed for every custom-made or modified item of equipment. Elemental Risk Assessments are also required for ‘standard’ items of equipment when such an item is to be operated in am manner not envisioned by the manufacturer, although such assessments may be derived from the manufacturer’s documentation.

The Elemental Risk Assessment should indicate the potential hazards associated with the equipment, its intended use, the tests to which the equipment should be subject, the interval for testing, and verification that the Operating Procedures are valid and appropriate. Generic Elemental Risk Assessments are permitted for standard laboratory items (e.g. conductivity bridges) even when there may be some small differences between each individual example.

Elemental Risk Assessments for custom equipment should be reviewed at an interval of two years, or twice the test interval, whichever is longer. A review is also required whenever the equipment is modified, or it is to be used in a substantially different manner.

These Elemental Risk Assessments do not replace the need for a Rig Risk Assessment.

2.6 OPERATING PROCEDURES All users should consult the Operating Procedures for an item of equipment before using the equipment. Moreover, if the Operating Procedures or Risk Assessment specifies that training is required, the use must seek and obtain this training.

For standard commercial equipment, the manufacturer’s operating procedures are all that is required, provided the equipment is to be used for the purpose envisaged by the manufacturer. Any deviation to this requires supplementary Operating Procedures to be developed and, potentially, an Elemental Risk Assessment.

All custom-made equipment requires Operating Procedures to be written. These procedures may be developed during the first six months following commissioning, provided the Laboratory Safety Officer deems the user competent. In such cases, the user will be responsible for developing the Operating Procedures and will be required to submit a first draft of these procedures to the Laboratory Safety Officer within two months of the equipment being commissioned.

Items that are identical or similar to items for which Operating Procedures already exist may refer to the existing procedures only after those procedures have been reviewed.

Where possible, all operating procedures should be provided in both electronic and hard copy. Where the source documentation is electronic, both the source file (TEX, Word or plain text) and a PostScript or Acrobat version must be logged


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with the Laboratory Safety Officer. Electronic copy in Acrobat format may be created from hardcopy by the use of a suitable scanner.

2.7 STANDARD PROCEDURES This section lists various standard procedures that must be adhered to for the majority of equipment. If any of these procedures is to be waived, the reasons for doing so and the associated risks must be discussed explicitly in the Rig Risk Assessment.

Spills of water are inevitable in the laboratory. If such spills occur over or close to electrical or electronic equipment then this represents a serious risk of electrocution. The standard procedures listed here will help reduce the risk to an acceptable level.

2.7.1 Positioning of Equipment Mains operated equipment must be positioned where it is not subject to splashes, chemicals spills, or other potentially hazardous contamination.

When located above water (or any other fluid), it must be fastened in such a way to prevent any chance of it falling into the fluid. Where possible, avoid mounting any item below a source of water. If this is unavoidable (e.g. some electric motors or pumps) careful consideration must be given to minimise the chance of the water reaching live connections.

The equipment must not be located where it is likely to fall or otherwise suffer mechanical damage. Where necessary, the technicians will make special brackets to hold the equipment securely.

2.7.2 RCD Protection All equipment should be connected to the mains only through a Residual Current Device (RCD). These devices are designed to immediately cut the supply as soon as any imbalance occurs between the live and neutral wires, or when any current is detected in the earth wire. Note that this does not completely remove the chance of electrocution, but does decrease it significantly.

The RCD should be installed as the first component when connecting to the mains. Where possible, wall-mounted RCD sockets should be employed. If this is not possible, RCD plugs or RCD adapters (in that order of preference) should be used. There is no harm (but also no advantage) in having more than one RCD in the circuit to a given item of electrical equipment.

RCDs should be checked at least once a month using their integrated ‘test’ facility.

Computer equipment may be connected without an RCD unless there is a chance that it may be exposed to splashes. As a rule, computer equipment should always be located where there is no chance of such exposure. Note, however, that if the computer is in any way connected to a probe or control circuit, then an RCD is required.

2.7.3 Switching Never turn off, connect or disconnect equipment when your hands are wet, or when standing on a wet floor.


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Similarly, do not operate equipment with wet hands or when you are in contact with water unless the equipment has been designed to allow safe operation when wet. In such cases, the need for such operation and the risks involved must be assess in the Risk Assessment.

Ensure the power to the equipment may be safely shut off in the event of an accident. This should be marked clearly as it may be necessary for someone unfamiliar with the equipment or rig to do so.

Any cut-out switch should be of a type that may be operated safely with wet hands. Operation of the cut-out switch should be tested at six-month intervals.

2.7.4 Extension leads and plug boards Extension leads and plug boards may be used to provide a suitable number and location of electrical sockets.

No more than one additional plug board may be connected to a plug board.

The total electrical load on the plug board must not exceed the rating of the plug board, and the total electrical load on a given double socket must not exceed 20A.

Plug boards must be positioned where there is no danger of them being splashed, stood on, or likely to be immersed in the event of an accidental spillage.

Cables leading both too and from the plug board must be kept tidy and routed to ensure they do not represent a risk of entanglement. Cables must not be under strain, and nor should they be of excessive length.

Double adapters must never be used.

2.7.5 Earth bonding All permanent and substantial equipment containing exposed metalwork must be earth bonded. Earth bonding consists of providing wires, straps or other direct electrical connection between each piece of metal, and connecting this into a good earth.

The Electrical Safety Assessor will check the integrity of these connections.

2.7.6 Submersible equipment Submersible equipment such as pumps and immersion heaters must only should preferably be used in tanks where a suitable route to earth is provided. This route to earth may be provided by an earth connection on the submersible unit, by earth bonding of metal work exposed to the water, or by the insertion of an earth electrode into the tank.

If the earth connection is provided by a separate electrode, then this electrode should be positioned so that it has at least 200mm2 contact with the working fluid when the fluid is at the lowest level likely to be encountered.

The earth electrode must be kept clean and free from corrosion. It is recommended that the electrode be constructed from stainless steel and is located at the bottom of a tank side wall (location on the tank floor may allow an insulating layer of particles to form on top of the electrode).

The earth electrode must be connected to a suitable earth. For fixed installations, this should be a permanent route to earth. For moveable equipment, it is


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recommended that the connection be made through the same RCD-protected circuit as the electrical equipment used with the tank. This connection may be through a dedicated earth terminal on the electrical equipment, or using an adapted earth-only mains plug inserted into a socket.

2.7.6.1 Faults

Any instances of blown fuses either in the plugs or in the equipment must be reported to the Electronics Technician. The equipment must be inspected by the Technician to ascertain the cause prior to the fuse being replaced.

Any instances of the local RCD tripping must be reported to the Electronics Technician. All the equipment on the circuit that tripped, or any other equipment connected to this through signal cables, must be inspected by the Technician to ascertain the cause prior to any of the equipment on the tripped circuit being used again.

Any instances of thermal cut-outs operating must be reported to the Electronics Technician. The equipment must be inspected by the Technician to ascertain the cause prior to any of the equipment being used again.

2.8 DISPOSAL If an item of equipment is sold, given away or otherwise disposed of, the equipment must be marked with a sticker stating that it has not been electrically tested and that it is the recipient’s responsibility to ensure the electrical safety before use. In the case of any equipment disposed of through the rubbish, the plug must be cut off.

2.9 PEOPLE 2.9.1 User

For the purposes of this document, the User is the person or group of people who will make direct use of the equipment. In the case of a group, every member must understand any limits or procedures imposed by the Risk Assessment or Operational Procedures.

2.9.2 Electrical Safety Assessor The Electrical Safety Assessor is required to assess the safety (or otherwise) of an experimental rig as a whole. The Director of the Fluid Dynamics Laboratory will appoint appropriate Assessors once he is satisfied of their competence to undertake this task.

The Electronics Technician is an Electrical Safety Assessor.

3 Tests This section outlines the various standard tests that may be performed on electrical and electronic equipment. Additional tests for certain categories of equipment are detailed under the documentation for that equipment.

3.1 BRAND NEW EQUIPMENT Brand new equipment must be tested or, if it carries the appropriate certification (e.g. a CE mark), may be deemed ‘safe’ based that certification, provided the level of testing required for that certification is at lease comparable with the procedures


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laid out in this document. If the equipment is deemed safe based on the manufacturer’s testing then the test sticker should be completed with ‘New’ in place of the date tested, and with an appropriate date entered for the date the next test is due. All equipment processed in this manner must be logged and the record sheet must indicate that no tests were undertaken.

3.2 EQUIPMENT FROM OTHER SOURCES Equipment that has been tested by another source (e.g. another department in the University) should be inspected by someone authorised to undertake electrical testing. If such equipment appears to be in good order and the tester is satisfied that the test procedures the equipment has been subjected to previously are adequate, then the equipment may be handled in a manner similar to that for brand new equipment. The date for the next test should be calculated based on the information contained on the existing sticker. If this produces a different date for the next test than is indicated on the existing sticker, then the earlier of the two dates must be selected. All equipment processed in this manner must be logged and the record sheet must indicate that no tests were undertaken.

3.3 STANDARD TESTS 3.3.1 Cable damage

Visual inspection.

Any cuts, abrasions, distortions or bad kinks in the cable, or damage to the connectors, are to be rectified by replacing the cable. This work must be carried out before proceeding with any of the other tests.

The integrity of the cable clamps should be confirmed at both ends of the cable. Any fault or inadequacy found is to be rectified.

3.3.2 Casing damage and condition Visual inspection.

Any damage to the equipment case should be mended and a risk assessment undertaken on the adequacy of the repair. When the casing cannot be repaired to an acceptable standard, the casing must be replaced or the equipment decommissioned.

Ventilation slots, heat sinks and fans must be clear of obstruction.

Any build-up of dust or grease must be removed.

3.3.3 Fuse rating Visual inspection.

The rating of the fuse in the plug must not exceed the rating of the associated cable.

The type and rating of any user-replaceable fuse in the equipment must be in accordance with the manufacturer’s specification.

3.3.4 Earth bond If not double-insulated.


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The electrical resistance between all exposed metal parts and the earth terminal on the connector should not exceed 0.1Ω. Circumstances where the resistance exceeds this value should be investigated and, when there is an acceptable reason for higher values, this should be noted on the test sheet. A resistance exceeding 0.1Ω must either lead to the equipment being repaired or decommissioned, or lead to a full Risk Assessment being undertaken.

If an earlier test or Risk Assessment has recorded a resistance more than 20% lower than the new figure, the reasons for this must be explained and assessed.

3.3.5 Insulation This test applies 500V DC between the power conductors and a nominal earth. This test should not be performed on electronic equipment.

This test is different if earthed or double-insulated equipment. For earthed equipment, the test is between the combined live/neutral pins and the earth pin. For double-insulated equipment, the test is between the combined live/neutral pins and a probe applied to the outside of the case. For submersible double-insulated equipment, the second probe may be applied to the liquid surrounding the submersed item; this will provide a check for any cracks in the insulation through which the liquid may penetrate.

If the insulation is found to be less than 2MΩ, then the equipment must be repaired or decommissioned.

3.3.6 Operational Check that current within specified limits.

The equipment should be run in accordance with the standard operational procedures and the current drain measured. This current should be within 20% of the value specified by the manufacturer (or in any Risk Assessment).

The source of any unexpected noise should be investigated.

Any evidence of sparking (except if as an intended part of the equipment design) must be investigated.

Failure of this test must either lead to the equipment being repaired or decommissioned, or lead to a full Risk Assessment being undertaken.

3.3.7 Earth leakage Should be less than 3mA.

This leakage should include all routes to earth, not just any earth connection the equipment might have.

3.4 FLASH TESTS Due to the possibility of damage to the associated equipment and insulation, this test is not to be performed..

3.5 SUPPLEMENTARY TESTS The standard tests outlined above in §3.3 apply to all equipment. For some categories of Laboratory equipment, additional tests are desirable. These supplementary tests include, for example, tests for submersible pumps whilst


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actually submersed, and confirmation of earth terminals and routes to earth for probes. Recommended supplementary tests for each category of equipment are listed in §7.

4 Documentation 4.1 RECORD SHEET

The test record sheet for every item should be completed. If an item fails, this should be recorded, along with details of the cause of failure. Details of the remedy should also be recorded.

Any item that deviates from the expected performance (e.g. the operational current), must be noted along with the conditions under which the deviation was found. Future tests should always include assessing whether this level of deviation has changed.

When a record sheet is changed, it must be moved to the ‘Updated’ folder. At regular intervals, the details in this folder will be added to the database and the corresponding sheets returned to the main folder.

If an item is disposed of, the record sheet should be removed from the main series and transferred into the ‘Decommissioned’ folder. The reason for decommissioning should be recorded.

4.2 TEST STICKER Every item passing the test procedures should be marked with an appropriate test sticker indicating the initials of the person responsible for the test, the date tested, and the date the next test is due.

Cables and equipment must both have test stickers attached, unless the cable is an integral (non-removable) part of the equipment. For the cable, the test sticker should be located close to the mains plug. For the equipment, the test sticker should be located in such a position that it is obvious to anyone attempting to operate the equipment.

An item failing the test should be immediately removed from service and a ‘Failed Electrical Test – Do Not Use’ notice attached to the plug and over the face of the item.

4.3 DATABASE The database should reflect the contents of the Record Sheets and tie this information in with the main equipment inventory, operation manuals and risk assessments.

The database should be updated at regular intervals (at least quarterly) from the Record Sheets contained in the ‘Updated’ folder. Once the details contained by an updated Record Sheet has been transferred to the database, the sheet should be marked and returned to the main folder.

Once a quarter, the database should be used to generate a list of equipment for which a test is over due, and a list of tests due in the coming quarter.


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5 Office Equipment 5.1 OFFICE APPLIANCES

5.1.1 Desk lamps Elements of risk assessment • Location. • Proximity to combustible material. • Routing of cable.

Test interval • Three years.

Tests required • Standard tests. • Switch.

5.1.2 Fans Elements of risk assessment • Location. • Routing of cable. • Stability.


Tests required • Standard tests. • Finger guards.

5.1.3 Heaters Elements of risk assessment • Location. • Routing of cable. • Stability. • Proximity to flammable materials.


Tests required • Standard tests. • Finger guards. • Tilt switch.


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5.2 KITCHE AND CLEANING 5.2.1 Kettles

Manual kettles are not permissible.

Elements of risk assessment • Location. • Routing and length of cable. • Stability. • Proximity to flammable materials.


Tests required • Standard tests. • Automatic turn off.

5.2.2 Microwaves Manual kettles are not permissible.

Elements of risk assessment • Location. • Routing and length of cable. • Operator instructions. • Suitable cooking implements. • Cleanness.


Tests required • Standard tests. • Timer.

5.2.3 Vacuum cleaners Elements of risk assessment • Dry or wet and dry usage. • Period of operation. • Storage location. • Dust filtering. • Use with toner spillages.

Test interval • One year.

Tests required • Standard tests.


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• RCD plug (if wet and dry ability).

5.3 IT EQUIPMENT 5.3.1 Computers

Elements of risk assessment • Location.

Ergonomics. • Routing of cables.

Power and data. • Interchangeable power cables.

These must be designated explicitly to the associated IT item and not interchanged with any other cable. The 13A mains plug must be clearly marked as to which item it belongs to. It is recommended that the IEC connector is also marked. The cable must carry a test sticker and be re-tested at the same time as the computer. If either the cable or the computer has a test sticker that is out of date, then both must be re-tested.


Tests required • Standard tests. • Cable. • Dust. • Fan operational. • Obstruction of ventilation. • Internal operational temperatures (where motherboard/BIOS provide these).

5.3.2 Computer monitors Elements of risk assessment • Routing of cables. • Adequacy of ventilation. • Refresh rate and interference. • Stability and crispness of picture. • Ambient illumination. • Ergonomics. • Interchangeable power cables.

These must be designated explicitly to the associated IT item and not interchanged with any other cable. The 13A mains plug must be clearly marked as to which item it belongs to. It is recommended that the IEC connector is also marked. The cable must carry a test sticker and be re-tested at the same time as the monitor. If either the cable or the monitor has a test sticker that is out of date, then both must be re-tested.


25 March 2004 – 18 –


Tests required • Standard tests. • Obstruction of ventilation.

5.3.3 Laptops Elements of risk assessment • Damage due to transportation.

Especially of power cables and power supplies. • Connection to other standards.

Any adapters should be tested.


Tests required • Standard tests. • Cable. • Adapter.

5.3.4 Printers Elements of risk assessment • Adequacy of ventilation. • Toner spillage. • Interchangeable power cables.

These must be designated explicitly to the associated IT item and not interchanged with any other cable. The 13A mains plug must be clearly marked as to which item it belongs to. It is recommended that the IEC connector is also marked. The cable must carry a test sticker and be re-tested at the same time as the printer. If either the cable or the printer has a test sticker that is out of date, then both must be re-tested.


Tests required • Standard tests. • Cable. • Obstruction of ventilation. • Filters. • Internal dust and toner.

5.3.5 Data hubs


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Elements of risk assessment • Routing of cables.



5.4 COMMUNICATION EQUIPMENT 5.4.1 Answerphones and dictation machines





5.4.2 Fax machines Elements of risk assessment • Location.




5.5 REPRODUCTION EQUIPMENT 5.5.1 Photocopiers

The testing of this equipment is part of the Service Contract for this equipment.

Elements of risk assessment • Adequacy of ventilation. • Toner spillage.

Test interval • As recommended in Service Contract.

Tests required • As recommended in Service Contract.

5.5.2 Binders


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5.6 PROJECTION EQUIPMENT 5.6.1 Slide projectors

Elements of risk assessment • Routing of cables. • Dazzle of lecturer.


Tests required • Standard tests. • Fan & ventilation slots. • Procedure for replacing bulb.

5.6.2 Overhead projectors Elements of risk assessment • Routing of cables. • Dazzle of lecturer.



5.6.3 Data projectors Elements of risk assessment • Routing of cables. • Dazzle of lecturer.



25 March 2004 – 21 –


Video tape recorders Elements of risk assessment • Location

Ergonomics. • Routing of cables. • Potential blockage of ventilation slots.

The flat top of a VTR is an attractive place for paper, books, tapes, etc. This may lead to a blockage of the ventilation slots.



6 General Equipment 6.1 CATERING EQUIPMENT

All catering equipment in the Pavilion A kitchen is the responsibility of the University Catering Service. Members of the Department do not have access to this equipment. All testing and servicing of this equipment will be arranged by the University Catering Service.

6.2 PLANT All plant, including machinery located in the Plant Room, wall-mounted or under-bench water heaters, hand driers, extract equipment and other fixed equipment is the Responsibility of Estate Management and Building Services. Members of the Department have a responsibility to report any faults, but EMBS will arrange for any tests necessary.

6.3 LIGHTING AND SOCKETS The testing of all fixed lighting, fixed sockets, emergency lighting, etc., is the responsibility of Estate Management and Building Services.

7 Laboratory Equipment 7.1 OFFICE APPLIANCES

7.1.1 Desk lamps Elements of risk assessment • Location. • Proximity to combustible material. • Protection for luminary.


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• Availability of low-voltage alternative.

Test interval • Three years if in Office. • Two years if in Laboratory.

Tests required • Standard tests. • Switch.

7.1.2 Fans Elements of risk assessment • Location. • Stability.

Test interval • Three years if in Office. • Two years if in Laboratory.


7.1.3 Vacuum cleaners Elements of risk assessment • Dry or wet and dry usage. • Use in wet environment. • Period of operation. • Unattended operation.


Tests required • Standard tests. • RCD plug (wet and dry).

7.2 LABORATORY APPLIANCES 7.2.1 Densitometer

Elements of risk assessment • Frequency of relocation.




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• Dust in heater/cooler unit. • Leaks.

7.2.2 Refrigerator Elements of risk assessment • Nature of contents. • Location of electrics in event of leakage.


Tests required • Standard tests. • Dust on condenser & compressor. • Corrosion damage. • Warning notices.

7.2.3 Freezer Elements of risk assessment • Nature of contents. • Use: storage or experiment. • Risk of damage from experiments. • Location of electrics in event of leakage.

Test interval • Two years.

Tests required • Standard tests. • Dust on condenser & compressor. • Corrosion damage. • Warning notices. • Temperature within acceptable range.

7.3 IT EQUIPMENT 7.3.1 Computers

Elements of risk assessment • Office or Laboratory location. • Location relative to experiments. • Risk of splashing. • Connection to control or measurement circuits. • Connection to data ports and other computer peripherals.


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Tests required • Standard tests. • Dust. • Fan operational. • Obstruction of ventilation. • Internal operational temperatures (where motherboard/BIOS provide these).

7.3.2 Computer monitors Elements of risk assessment • Office or Laboratory location. • Location relative to experiments. • Risk of splashing. • Adequacy of ventilation. • Refresh rate and interference. • Stability and crispness of picture. • Ambient illumination. • Ergonomics.



7.3.3 Printers Elements of risk assessment • Office or Laboratory location. • Risk of splashing. • Adequacy of ventilation.


Tests required • Standard tests. • Obstruction of ventilation. • Filters. • Internal dust and toner.

7.3.4 Data hubs


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Elements of risk assessment • Risk of splashing. • Risk due to faults in attached equipment.



7.3.5 Portable equipment Elements of risk assessment • Location. • Use of multi-standard adapters.



7.4 VIDEO EQUIPMENT AND CAMERAS 7.4.1 Video tape recorders

Elements of risk assessment • Location relative to experiments. • Risk of splashing. • Risk of contamination through ventilation slots.

Unlike computers, ventilation slots tend to be located in the top of the VTR. Contamination may cause either an electrical or a mechanical problem.

• Potential blockage of ventilation slots. The flat top of a VTR is an attractive place for paper, books, tapes, etc. This may lead to a blockage of the ventilation slots.

• Connection to computers or controllers. • Connection to data ports and other computer peripherals.



7.4.2 Video monitors Elements of risk assessment • Office or Laboratory location. • Location relative to experiments.


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• Risk of splashing. • Adequacy of ventilation. • Stability and crispness of picture. • Equipment stacks.

Video monitors are often positioned directly on top of VTRs. While this practice is acceptable, it is not acceptable to subsequently position any further equipment or items on top of the video monitor.



7.4.3 Video timers Elements of risk assessment • Location relative to experiments. • Risk of splashing. • Adequacy of ventilation.



7.4.4 High-speed cine camera Elements of risk assessment • Location relative to experiments. • Risk of splashing. • Trip hazard from stand.



7.4.5 Video cameras Most video cameras operate on a low voltage, using either batteries or an external power supply. The present section deals only with those cameras having a direct connection to the mains supply.

Elements of risk assessment • Location relative to experiments. • Risk of splashing.


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• Adequacy of mounting arrangements.



7.4.6 Camera power supplies Elements of risk assessment • Location relative to experiments. • Risk of splashing or leaks. • Risk of mechanical damage. • Adequacy of physical attachment.

This is particularly relevant on turntables.


Tests required • Standard tests. • Obstruction of ventilation. • Damage to low voltage cable.

7.5 LIGHT SOURCES 7.5.1 Projectors

Elements of risk assessment • Location relative to experiments. • Risk of splashing or leaks. • Risk of mechanical damage. • Proximity to flammable materials. • Adequacy of physical attachment.

This is particularly relevant on turntables, tripods and when light sources are mounted in any orientation other than sitting on a bench.

• Control of stray light. Even the relatively low intensities from a standard slide projector represent a hazard, both directly to the eyes, and through dazzling laboratory users. Measures must be taken to ensure no light causes a risk or inconvenience to other Laboratory users.




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• Operation of fan. • Integrity of tripod plate or other mounting system.

7.5.2 Photographic lamps Elements of risk assessment • Location relative to experiments. • Risk of splashing or leaks. • Risk of mechanical damage. • Proximity to flammable materials. • Risk to user of casing temperature.

These lamps run very hot. The case is fitted with a thermal cut-out to switch the lamp off if the case temperature exceeds 150oC, but this temperature is still sufficiently high to burn a user trapped against the lamp.

• Adequacy of ventilation. These lamps should not have their fans or ventilation slots hindered in any way.

• Adequacy of physical attachment. • Control of stray light.

The high intensities from these lamps represent a serious hazard, both directly to the eyes, and through dazzling laboratory users. Measures must be taken to ensure no light causes a risk or inconvenience to other Laboratory users. Non-combustible materials must be used for any shielding closer to the lamp than 500mm. All shielding must be secured firmly and designed to prevent any hindrance to the air flow through the lamp.

• Can low voltage lamps or light sources in other locations be used instead? The typical location of these turntable lamps exposes the user to greater risk than would be the case if the lighting was provided by low voltage lamps or provided from a remotely mounted lamp.


Tests required • Standard tests. • Obstruction of ventilation. • Case temperature.

7.5.3 Turntable lamps Elements of risk assessment • Location relative to experiments. • Risk of splashing or leaks. • Risk of mechanical damage. • Risk of injuring entangling user.

These lamps are intended for mounting on a turntable. As such, they will normally be in motion relative to the user, introducing additional potential hazards.


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• Proximity to flammable materials. • Adequacy of physical attachment. • Control of stray light.

Even the relatively low intensities from a standard slide projector represent a hazard, both directly to the eyes, and through dazzling laboratory users. Measures must be taken to ensure no light causes a risk or inconvenience to other Laboratory users.




7.5.4 Fluorescent lamps Elements of risk assessment • Location relative to experiments. • Risk of splashing or leaks. • Risk of mechanical damage.

The fluorescent tubes are particularly susceptible to breakage. Moreover, if broken, they represent a greater hazard due to the cocktail of fluorescent materials they contain.

• Proximity to flammable materials. Fluorescent lamps run relatively cool and may safety be used much closer to flammable materials than most other light sources. However, it is important that adequate ventilation be maintained when doing so.

• Adequacy of physical attachment. • Can low voltage lamps or light sources in other locations be used instead?

It is sometimes necessary to locate these lamps below an experimental apparatus, thus exposing the lamps to a significantly increased risk from leaks and splashes. The possibility of using low voltage lamps or other remote sources of light should be considered.


Tests required • Standard tests. • Diffusers and end caps.

The diffuser and end caps provide part of the protection to the tube and electrics within the lamp. The diffuser and end caps, or a suitable alternative arrangement, must be secure and intact.

• Temperature.


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The operational temperature, when the lamp has been left on for a number of hours, should be checked if air flow around the lamp is hindered in any way.

7.5.5 Light boxes Elements of risk assessment • Location relative to experiments. • Risk of splashing or leaks. • Risk of mechanical damage.

Test interval Two years.

Tests required Standard tests

7.5.6 Arc lamps The xenon arc lamps consist of a separate power supply and lamp unit. The power supply generates both very high voltages (30kV) for striking the arc, and high currents (at relatively low voltages) for maintaining the arc. For most of the units, the power supply and lamp unit are permanently wired together, but for one it is possible to disconnect the two.

Elements of risk assessment • Location relative to experiments.

The relatively short length of the cables connecting the lamp unit to the power supply can cause difficulty. It is important to ensure that this cable is not put under any significant strain, and that both the lamp and the power supply are mounted in a secure fashion in a safe location.

• Risk of splashing or leaks. These lamps use very high voltages (30kV) to strike the ark. Any splashes or moisture may lead to the user being exposed to these voltages.

• Risk of mechanical damage. The cables and terminals connecting the lamps and power supplies are particularly vulnerable. Due to the high voltages associated with striking the ark, it is extremely important that the insulation remains intact.

• Proximity to flammable materials. The collimated or focused light produced by the arc lamps is potentially extremely hot and capable of igniting most flammable materials if placed within 500mm of the lamp. The use of a cold mirror or cold window to filter the heat from the light reaching an experiment is strongly recommended.

• Adequacy of ventilation. These lamps and their power supplies must not have their fans or ventilation slots hindered in any way.

• Adequacy of physical attachment. Both the power supply and lamp unit need to be attached securely.

• Control of stray light. The high intensities from these lamps represent a serious hazard, both directly to the eyes, and through dazzling laboratory users. Measures must be taken to


25 March 2004 – 31 –

ensure no light causes a risk or inconvenience to other Laboratory users. Non-combustible materials must be used for any shielding closer to the lamp than 500mm. All shielding must be secured firmly and designed to prevent any hindrance to the air flow through the lamp.



This short test interval is required due to the presence of the high voltages associated with striking the arc.

Tests required • Standard tests. • Obstruction of ventilation of power supply. • Obstruction of ventilation of lamp. • Check cable to lamp. • Check and clean cable terminals/connectors.

7.5.7 Strobe lights Elements of risk assessment • Location relative to experiments. • Risk of splashing or leaks. • Risk of mechanical damage. • Adequacy of physical attachment. • Control of stray light.

The high intensities from these lamps represent a serious hazard, both directly to the eyes, and through dazzling laboratory users. Measures must be taken to ensure no light causes a risk or inconvenience to other Laboratory users.



7.6 LASERS Not currently in use. Secured under lock and key.

7.7 POWER SUPPLIES 7.7.1 Bench supplies

Elements of risk assessment • Location relative to experiments. • Risk of splashing or leaks.


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It is often possible and desirable to locate the power supplies well clear of the experiment, bringing only low-voltage connections through to the experiment.

• Adequacy of ventilation. • Adequacy of physical attachment.

When the supply is integrated into an experimental rig such as a rotating table, it is essential that it is firmly attached.

• Low-voltage route to earth. Under most circumstances the low voltage side of the power supply should be earth-referenced. This will ensure that, in the event of power supply failure, the equipment will remain safe. This earth referencing is most conveniently achieved at the power supply itself; often power supplies have an earth terminal and a removable strap between this and either the positive or negative side. If connection to earth is not possible or not desirable (e.g. to avoid earth loops), then an earth point should still be provided somewhere in the equipment.


Tests required • Standard tests. • Obstruction of ventilation. • Earth terminal.

7.7.2 Plug-in adapters Elements of risk assessment • Location relative to experiments. • Risk of splashing or leaks.

It is often possible and desirable to locate the power supplies well clear of the experiment, bringing only low-voltage connections through to the experiment.

• Adequacy of ventilation. Free movement of air around the adapter must be maintained. As most adapters have internal temperature fuses, failure to observe this is likely to lead to the adapter ceasing to function. Note that under normal circumstances the Laboratory will not attempt to repair any plug-in adapters following failure of this fuse.


Tests required • Standard tests. • Low voltage cable insulation.

7.7.3 High voltage supplies This category of equipment is for power supplies generating voltages in excess of mains voltages. Where at all possible, alternative solutions not requiring such voltages should be employed.


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The presence of high voltages, the generation of interference and the need to keep cables relatively short complicate the location of high voltage supplies. It is critical that the high voltage cables are not put under strain and do not run through an area where they are likely to suffer damage or be exposed to electrolytes.

• Risk of splashing or leaks. Any splashes or moisture may lead to the user being exposed to these voltages.

• Risk of mechanical damage. The high voltage cables are especially sensitive and prone to damage. Where these cables must be exposed, they should be provided with some for of covering or armouring. The cables and terminals connecting the lamps and power supplies are particularly vulnerable. Due to the high voltages associated with striking the ark, it is extremely important that the insulation remains intact.

• Adequacy of physical attachment. The power supply, cables and any associated equipment need to be attached securely.

• Can low voltage equipment be used instead? Where possible, low voltage equipment should be used instead. Where only high-voltage equipment is feasible, the reasons behind this must be given explicitly in the Risk Assessment.


Tests required • Standard tests. • Check HV insulation.

7.8 LABORATORY INSTRUMENTATION 7.8.1 Amplifiers

Elements of risk assessment • Location relative to experiments. • Risk of splashing or leaks. • Adequacy of physical attachment. • Earth for probes.

Probe casings should normally be earthed. If this is not possible, or not desirable (e.g. due to the formation of ‘earth loops’), a separate earth electrode must be incorporated into the design of the apparatus.

• Risk to/from attached equipment. What risks might the user be exposed to if any attached equipment fails? Does failure of this equipment have other vectors with potential risk (e.g. probes).



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Tests required • Standard tests. • Input/output isolation.

7.8.2 Bridge circuits Elements of risk assessment • Location relative to experiments. • Risk of splashing or leaks. • Adequacy of physical attachment. • Earth for probes.

Probe casings should normally be earthed. If this is not possible, or not desirable (e.g. due to the formation of ‘earth loops’), a separate earth electrode must be incorporated into the design of the apparatus.

• Risk to/from attached equipment. What risks might the user be exposed to if any attached equipment fails? Does failure of this equipment have other vectors with potential risk (e.g. probes).


Tests required • Standard tests. • Probe isolation.

7.8.3 Multimeters Battery-powered multimeters should also be tested.

Elements of risk assessment • Location relative to experiments. • Risk of splashing or leaks. • Adequacy of physical attachment. • Probe insulation.

This must be adequate to withstand the maximum voltage present on the experimental rig, not just the voltage that is to be measured.



7.8.4 Oscilloscopes Elements of risk assessment • Location relative to experiments.

By use of probe cables of a suitable length, the location of the oscilloscope need not be close to the experiment.


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• Risk of splashing or leaks. • Adequacy of physical attachment. • Probe insulation.

This must be adequate to withstand the maximum voltage present on the experimental rig, not just the voltage that is to be measured.



7.8.5 High voltage equipment This category of equipment is for equipment utilising voltages in excess of mains voltages. Where at all possible, alternative solutions not requiring such voltages should be employed.


The presence of high voltages, the generation of interference and the need to keep cables relatively short complicate the location of high voltage supplies. It is critical that the high voltage cables are not put under strain and do not run through an area where they are likely to suffer damage or be exposed to electrolytes.

• Risk of splashing or leaks. Any splashes or moisture may lead to the user being exposed to these voltages. This will occur at much lower levels of contamination than for standard voltage equipment.

• Risk of mechanical damage. The high voltage cables are especially sensitive and prone to damage. Where these cables must be exposed, they should be provided with some for of covering or armouring. The cables and terminals connecting the lamps and power supplies are particularly vulnerable. Due to the high voltages associated with striking the ark, it is extremely important that the insulation remains intact.

• Adequacy of physical attachment. The power supply, cables and any associated equipment need to be attached securely.

• Can low voltage equipment be used instead? Where possible, low voltage equipment should be used instead. Where only high-voltage equipment is feasible, the reasons behind this must be given explicitly in the Risk Assessment.




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• Check HV insulation.

7.9 MOTORS AND CONTROLLERS 7.9.1 Servo motor controllers

Elements of risk assessment • Location relative to experiments. • Risk of splashing or leaks. • Adequacy of physical attachment. • Earth-referencing.

Should the motor be earth referenced, or is it safer to have it floating? Earth-referencing in combination with a suitable fuse, circuit breaker or RCD may reduce the risk associated with higher voltage servo motors.


Tests required • Standard tests. • Output isolation.

7.9.2 Servo motors Elements of risk assessment • Location relative to experiments. • Risk of splashing or leaks. • Adequacy of physical attachment. • Risk of entanglement or injury.

Are guards required? Have all sharp corners been removed? • Earth-referencing.

Should the motor be earth referenced, or is it safer to have it floating? Earth-referencing in combination with a suitable fuse, circuit breaker or RCD may reduce the risk associated with higher voltage servo motors.


Tests required • Standard tests. • Output isolation.

7.9.3 AC motors Elements of risk assessment • Location relative to experiments. • Risk of splashing or leaks. • Adequacy of physical attachment. • Risk of entanglement or injury.


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Are guards required? Have all sharp corners been removed? • Low voltage alternatives.

Is it possible to use a low voltage motor instead?



7.10 PUMPS 7.10.1 Integrated pumps

Elements of risk assessment • Location within experimental rig. • Risk of splashing or leaks.

What additional risks will occur if the pump leaks – risks both due to the pump, and due to anything that may be contaminated as the result of the pump leaking?

• Adequacy of physical attachment. • Cable routing.

Does this take the best route available? Is it protected from mechanical damage? Is it possible to inspect the cable for damage?

• Switching and control. How is the pump to be controlled? Can it be shut off safely in the result of a leak or a detached hose?

• Guards. Some integrated pumps are not self-contained units. In such cases, the question of whether guards are necessary should be addressed.


Tests required • Standard tests. • Check for leaks.

7.10.2 Peristaltic pumps Elements of risk assessment • Location relative to experimental rig. • Risk of splashing or leaks.


• Adequacy of physical attachment.



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Tests required • Standard tests. • Check for leaks.

7.10.3 Submersible pumps Elements of risk assessment • Location within experimental rig. • Adequacy of physical attachment. • Route to earth.

If the pump or cable insulation fails, the water may become live. It is desirable that a suitable route to earth must always be is provided, either through earth-bonding of metal parts of the apparatus exposed to the water, or by the provision of an additional earth electrode of at least 200mm2 area, as outlined in §2.7.6 of the standard procedures.

• RCD on mains cable. The mains cable of the submersible pump should normally be fitted with an RCD plug, even if this will be plugged into circuits with other RCD protection.

Test interval One year.

Tests required • Standard tests. • Optional: check insulation and/or leakage current when submerged. • RCD required.

7.10.4 Vacuum pumps Elements of risk assessment • Location relative to experimental rig. • Risk of splashing or leaks. • Adequacy of physical attachment.



7.10.5 Double-bucket pumps Elements of risk assessment • Route to earth.

All metal work on the double buckets must be earth-bonded via the earth provided on the pump.

• RCD on mains cable. The mains cable of the submersible pump should normally be fitted with an RCD plug, even if this will be plugged into circuits with other RCD protection.


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Tests required • Standard tests. • Speed control. • RCD required. • Check for leaks. • Check shielding from water.

7.10.6 Variable speed pumps Elements of risk assessment • Location relative to experimental rig. • Risk of splashing or leaks.


• Adequacy of physical attachment. • Route to earth.

All metal work on the double buckets must be earth-bonded via the earth provided on the pump.


Tests required • Standard tests. • Speed control. • RCD required.

7.11 TURNTABLES 7.11.1 Turntables

Elements of risk assessment • Location of controller.

Can this be operated safely while the table is rotating? • Risk of splashing or leaks.

Is the controller located well clear of any splashes or leaks? Are the turntable motor and mains outlets adequately protected?

• Adequacy of physical attachment. Are all items on the turntable adequately secured?

• Risk of entanglement or injury. Are there sharp corners on the turntable or equipment mounted on it?

• Trip hazard. The routine of the cables between controller and turntable. Also any other potential hazards around the turntable base.


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• Emergency shut-off. Are the provisions for stopping the turntable in an emergency adequate? Will this also cut the power to the mains sockets?

• Maximum speed. Is there a limit on the maximum speed of the turntable? Is this limit safe? Who has the ability to change or over-ride this limit? What will happen if this limit is exceeded?


Tests required • Standard tests. • RCD required. • Shut-off switch. • Speed limiter.

Verify that turntable cannot be rotated faster than the maximum allowable speed.

7.12 LABORATORY EQUIPMENT 7.12.1 Heat baths

Elements of risk assessment • Location relative to experimental rig. • Risk of splashing or leaks.

What additional risks will occur if the bath or associated tubing leaks – risks both due to the bath, and due to anything that may be contaminated as the result of the bath leaking?

• Temperature control. What is the effect of the temperature control circuit failing (or user error), resulting in temperatures either much higher or much lower than intended?


Tests required • Standard tests. • Check for leaks. • Check earth leakage current when full.

7.12.2 Stirrers Elements of risk assessment • Location relative to experimental rig. • Risk of splashing or leaks.

What additional risks will occur if the bath or associated tubing leaks – risks both due to the bath, and due to anything that may be contaminated as the result of the bath leaking?


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7.12.3 Scales Elements of risk assessment • Location. • Contamination by chemicals.



7.12.4 Immersion heaters Elements of risk assessment • Location within experimental rig. • Risk of drying out.

What will happen if the heater does not remain immersed? • Route to earth.

If the insulation fails, the water may become live. A suitable route to earth must always be provided. In most cases this will be through the metal case of the immersion heater. If this route is not possible, the route to earth may either be through earth-bonding of metal parts of the apparatus exposed to the water, or through the provision of an additional earth electrode of at least 200mm2 area, as outlined in §2.7.6 of the standard procedures.

• RCD on mains cable. The mains cable of the immersion heater should normally be fitted with an RCD plug, even if this will be plugged into circuits with other RCD protection.


Tests required • Standard tests. • Check for leaks. • Check leakage current when immersed. • RCD required.

7.13 FRAMEWORKS AND TANKS 7.13.1 Metalwork

Elements of risk assessment • Live metalwork.


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The metalwork of tanks may become live due to the failure of equipment, the incorrect connection of equipment, or as a result of stray electromagnetic fields. To prevent this happening, all metalwork must be connected to earth as described by the wiring regulations BS7671. A conductor with cross-section not less than 6mm2 must connect all fixed frames to a suitable earth. Water supply pipe work may be used as the earth only once its continuity to earth has been adequately verified to have a resistance of less than 0.1Ω. Moveable frameworks and tanks must be provided with a suitable earth terminal and lead. This earth lead must be connected to a suitable earth whenever the framework or tank is used in conjunction with any electrical equipment. It is recommended that the connection be made through the same RCD-protected circuit as the electrical equipment used with the framework or tank. This connection may be through a dedicated earth terminal on the electrical equipment, or using an adapted earth-only mains plug inserted into a socket. Each electrically separate but mechanically integrated part of the metalwork must be connected with an earth strap of at least 2.5mm2 cross-section (4mm2 if not sheathed or mechanically protected). This earth strap may be omitted only when a reliable earth with a resistance of less than 0.1Ω is formed as an inherent part of the design of the framework or tank.


Tests required • Test earth bonding of all exposed metal work on frames and tanks.

7.14 POWER CORDS 7.14.1 Standard cords (IEC)

Elements of risk assessment • Routing. • Trip hazard. • Location.

In Office or Laboratory? • Use.

For computer or laboratory equipment?


Tests required • Visual inspection. • Earth continuity. • Fuse.


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7.14.2 Non-standard cords Elements of risk assessment • Routing. • Trip hazard. • Location.




Tests required • Visual inspection. • Earth continuity. • Fuse.

7.14.3 Cords with RCD Elements of risk assessment • Routing. • Trip hazard. • Location.




Tests required • Visual inspection. • Earth continuity. • Fuse. • RCD.

7.15 PLUG-BOARDS AND EXTENSION LEADS 7.15.1 Plug-boards

Plug-boards that are not integrated permanently into an experimental set-up.

Elements of risk assessment • Location relative to experimental rig. • Risk of splashing or leaks. • Routing of cable. • Length of cable.


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Excess cable should be avoided, within reason. Cable may only be coiled if the total load on the plug board is less than 50% of the rated load of the cable, and even then only coiled loosely (diameter of coil greater than 250mm). Similarly, cables should not be stretched taut.

• Trip hazard. • Standing.

The plug board must not be located where it may be accidentally kicked or stood on.

• Total electrical load. • Cascading

No plug board should have more than one further plug board connected to it either directly or indirectly,



7.15.2 Integrated plug-boards Plug-boards that are integrated permanently into an experimental set-up.



• Trip hazard. • Standing.

The plug board must not be located where it may be accidentally kicked or stood on.

• Total electrical load. • Cascading

No plug board should have more than one further plug board connected to it either directly or indirectly,

Test interval • Two years. • One year if not integrated into apparatus.


7.15.3 Extension Leads


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• Alternatives. Extension leads should generally be avoided except as a temporary measure. The alternatives (e.g. power from a different source) should be explored in advance.

• Trip hazard. • Total electrical load.

Test interval • One year. • One year if not integrated into apparatus.


7.16 RCDS 7.16.1 RCD adapters

Elements of risk assessment Test interval

Six months.

Tests required Visual inspection

Check trip current

7.16.2 RCD plugs Visual inspection

Check trip current

7.16.3 RCD sockets Visual inspection

Check trip current

7.17 FIXED INSTALLATIONS 7.17.1 Hand driers


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Elements of risk assessment • Cable routing. • Proximity of combustible material.



7.17.2 Heaters Elements of risk assessment • Cable routing. • Proximity of combustible material.



7.18 THREE-PHASE INSTALLATIONS 7.18.1 Wind tunnels

Elements of risk assessment Test interval • Three years.

Tests required • Standard tests. • Isolator. • Cut-out switch. • Operating procedures.

7.18.2 Flumes Elements of risk assessment Test interval • Two years.


7.18.3 Sump pump


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Elements of risk assessment Test interval • Two years.


7.18.4 Ventilation equipment Elements of risk assessment Test interval • Three years.

Tests required • Standard tests. • Isolator. • Cut-out switch.

8 Workshop 8.1 HAND TOOLS

8.1.1 Drills Elements of risk assessment • Damage to cable.

Indirect mechanical damage due to regular use and exposure to potentially abrasive or sharp obstacles.

• Contact with live circuits when drilling. Always check that nearby circuits are isolated before drilling.

• RCD protection. The drill should normally be connected to the mains through a RCD plug permanently wired to its cable.

• Eye protection. • Ear protection.



8.1.2 Grinders


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Elements of risk assessment • Damage to cable.

There are two principal sources of cable damage: indirect mechanical damage to the cable (from sharp or abrasive obstacles), and direct damage to the cable through it contacting with the grinding surface.

• Contact with live circuits when grinding. Always check that nearby circuits are isolated before grinding.

• RCD protection. The grinder should normally be connected to the mains through a RCD plug permanently wired to its cable.



Tests required • Standard tests. • RCD required.

8.1.3 Saws Elements of risk assessment • Damage to cable.

There are two principal sources of cable damage: indirect mechanical damage to the cable (from sharp or abrasive obstacles), and direct damage to the cable through it contacting with the saw blade.

• Contact with live circuits when grinding. Always check that nearby circuits are isolated before cutting.

• RCD protection. The saw should normally be connected to the mains through a RCD plug permanently wired to its cable.




8.1.4 Routers Elements of risk assessment • Damage to cable.

There are two principal sources of cable damage: indirect mechanical damage to the cable (from sharp or abrasive obstacles), and direct damage to the cable through it contacting with the router cutter.


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• RCD protection. The router should normally be connected to the mains through a RCD plug permanently wired to its cable.




8.1.5 Heat guns Elements of risk assessment • Damage to cable.

There are two principal sources of cable damage: indirect mechanical damage to the cable (from sharp or abrasive obstacles), and heat damage.



8.1.6 Soldering irons Elements of risk assessment • Damage to cable.

There are two principal sources of cable damage: indirect mechanical damage to the cable (from sharp or abrasive obstacles), and heat damage.



8.2 FIXED TOOLS Three Years

Elements of risk assessment • Eye protection. • Ear protection.

Test interval Three years.



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8.3 THREE-PHASE INSTALLATIONS 8.3.1 Milling machines

Elements of risk assessment Test interval

Three years.


Isolator

Cut-out switch

8.3.2 Lathes Elements of risk assessment Test interval

Three years.


Isolator

Cut-out switch

8.3.3 Drilling machines Elements of risk assessment Test interval

Three years.


Isolator

Cut-out switch

8.3.4 Compressor Elements of risk assessment Test interval

Three years.


Isolator

Cut-out switch


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8.3.5 Abrasion tools Elements of risk assessment Test interval

Three years.


Isolator

Cut-out switch

UNIVERSITY OF CAMBRIDGE Electrical Safety: Policy and Procedures

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Transcript of UNIVERSITY OF CAMBRIDGE Electrical Safety: Policy and Procedures