EKAS 2.19.31Flexible cords and plugs to 1000 V

UEE31307 Certificate III in

Refrigeration and Air ConditioningStage 2A

Units: UEENEEPOO3B

Chris HungerfordFriday, April 21, 2023

How is a flexible cord How is a flexible cord different from other cables?different from other cables?

• The conductors in a flexible cord are made up of many more strands of finer wire than an ordinary cable (0.3mm). This allows the cord to flex without breaking the conductors.

• The maximum cross-sectional area (CSA) of a conductor in a flexible cord is 4mm2.

• Finally, the maximum number of insulated conductors (or cores) in a single cord is five.

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Maximum length of flexible cordsMaximum length of flexible cords

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Maximum current rating of flexible cordsMaximum current rating of flexible cords

NOTES:1 Where a flexible cord is wound on a drum, multiply current-carrying capacity by the appropriate factor, as follows:Number of layers: 1 2 3 4Derating factor: 0.76 0.58 0.47 0.40

2 Flexible cords having tinsel conductors with a nominal cross-sectional area of 0.5 mm2 have a current carrying capacity of 0.5 A.

3 The current-carrying capacity is based on a cable maximum conductor operating temperature of 60°C in order to limit the surface temperatures for the expected use of such cables. Where flexible cords are used as fixed wiring, the current ratings are given in Tables 4 to 15 and 17. (Refer to Clause 3.3.2).

4 To determine the three-phase voltage drop, refer to the appropriate value in Table 46, Table 47 or Table 48. To determine the single-phase voltage drop, multiply the three-phase value by 1.155.

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An electrical cable is identified by its: 1. Conductor material e.g. copper or

aluminium2. Conductor size e.g. 1.5mm² CSA3. Insulation material e.g. rubber, glass, PVC4. Number of cable cores e.g. 7/0.50 – i.e. 7

strands of 0.50mm circular diameter 5. Voltage grading e.g. 0.6 / 1 KV; 250V /

440V6. Sheathing7. Protection

Electrical cables 3 Core & Earth Circular

Steel Wire Armoured SWASteel Wire Armoured SWA

Strand Conductor

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Ratings of cables

• Voltage rating, all cables have a maximum operating voltage. This is directly related to the type and thickness of the insulation material.

• Temperature rating, table 3.2 AS 3000: 2007.• Cables are NOT rated in Current Carrying

Capacity. A cable's current carrying capacity is determined buy how it is installed as per AS/NZS 3008.1.1 (Australian).

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Selecting a cord or cable• Current carrying capacity of the cable.

• Operating conditions;– temperature– voltage– installation factors such as in direct sunlight,

mechanical protection, & thermal installation.

• Number of conductors.

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Plugs and socketsPlugs and sockets• There are many types of multiphase plug tops• 3 pin 2 phase & E• 4 pin 3 phase & E• 5 pin 3 phase neutral & E• Multi pin, 3 phase neutral & E + control

35A 20A 15A

keyways

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An electrical cable is identified by its: 1. Conductor material e.g. copper or aluminium2. Conductor size e.g. 1.5mm² CSA3. Insulation material e.g. rubber, glass, PVC4. Number of cable cores e.g. 7/0.50 – i.e. 7

strands of 0.50mm circular diameter 5. Voltage grading e.g. 0.6 / 1 KV; 250V / 440V6. Sheathing7. Protection

Electrical cables

TPS Thermoplastic SheathedTPS Thermoplastic Sheathed

Sheathing

Strand Conductor

Insulation

3 Core & Earth Circular

Twin & Earth Flat

International Protection Numbers2.19.31.A

3.7.2.8 Flexible cordsJoints shall not be made in flexible cords.Exceptions: Joint in flexible cords may be made -(a) Where used as installation wiring(b) By means of suitable cable couplersAny flexible cord shall be installed so that undue stress on its

connections due to a pull on the cord is alleviated by a pillar, post, grip, tortuous path, or other effective means.

Knotting of the flexible cord shall not be acceptable for this purpose.

AS/NZS-3000:2007 SAA Wiring Rules

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Accessories• All accessories must be suitable and as

per Australian standards .

• All accessories must be suitable for the application.

• Wide variety of accessories can be accessed via suppliers catalogues.

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A=Excellent B=Good C=Fair D=Poor

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AS/NZS-3000:2007, SAA Wiring Rules

3.7 ELECTRICAL CONNECTIONS3.7.1 GeneralConnections between conductors and between conductors and other electrical equipment shall provide electrical continuity and adequate mechanical strength.

•Solder less lugs•Crimps•Compression terminals•Soldered connections

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3.7.2.2 Preparation for connectionThe insulation on a conductor shall not be removed any further than is necessary to make the connection.

For connections between insulated conductors the connection shall be insulated to provide a degree of insulation not inferior to that of the conductors.

Any damaged insulation shall be reinstated.

AS/NZS-3000:2007 SAA Wiring Rules

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Insulation of conductors

Yes

• Electrical insulation tape

• Epoxy kits

• Heat shrink

No

• Masking tape

• packing tape

• sticky tape

• silicon mastic

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Conductor colouringAS/NZS 3000 Table 3.4

Function Colour

Earth/bonding Green/yellow

Neutral Black

Red, Brown, dark Blue, Orange, Purple, Grey, White, any colour other than green/yellow, green, black, yellow or light blue

ActiveLight blue

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Terminations and connections

• Connections must not be soft soldered before compression terminations.

• Must be seated correctly.• Free of dirt and oxides.• Use a suitable lug or connector.• Insulated to the equivalent of the original

insulation.• Earth connection must be painted if

exposed to weather

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3.7.2.6 Mechanical stressAll cables and conductors shall be installed so that there is no undue mechanical stress on any connection.

AS/NZS-3000:2007 SAA Wiring Rules

3.7.2.3.1 Loosening of connections

Connections shall be made so that no loosening is likely because of vibration, alteration of materials or temperature variations to which the connectionsare likely to be subjected in normal service.

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The eight visual checks recommended are:1. Check for obvious damage or defects.2. Check that flexible cords are properly anchored3. Check for any damage to flexible cords.4. Check that maximum load warning labels are intact. 5. Check that any controls such as switches are in working order.6. Check that covers and guards are properly secured as intended.7. Check that any safety devices are in good working order.8. Check that vents or exhausts are unobstructed.

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Earth Continuity Test

• Any Class I equipment with exposed metal parts must have its protective earth checked to ensure it is continuous from the earth pin of the plug to any exposed metal. The resistance must not be greater than 1Ω.

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Instrument Low reading ohmmeter.

Earth Continuity

1

Earth Pin

To

Earth Socket

2.19.31.DInstrument Low reading ohmmeter.

What is the value of earth continuity?

Earth Continuity “Class 1”

2.19.31.DWhat is the value of earth continuity?

Instrument Low reading ohmmeter.

Earth Pin to exposed Metal

Insulation Resistance Test:• All equipment must be tested to ensure the

integrity of the insulation, no electricity must be allowed to escape from the conductors or the appliance.

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Scale

Scale multiplierInsulation resistance Tester

Megohmmeter

Insulation Resistance “Class 1”

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Megohmmeter

Q What is the value of insulation resistance?

Actives & Neutral To Earth Pin & Exposed Metal

Insulation Resistance “Class 2”

Active & Neutral To Exposed Metal

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Megohmmeter

Q What is the value of insulation resistance?

Insulation Resistance “extension lead”

Actives & Neutral

To

Earth Pin

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1M1

Megohmmeter

Q What is the value of insulation resistance?

Polarity

low

Active Pin

To

Active Socket

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1

Instrument Low reading ohmmeter.

What is the value of continuity?

Polarity

low

Neutral Pin

To

Neutral Socket

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1M1

Instrument Low reading ohmmeter.

What is the value of continuity?

What should the voltage be?

V1 240vV2 415vV3 415v

Is this correct?

Reversed polarity L2 -N

Is this correct?

Reversed polarity L3-E

V1=?

V3=?

V2=?

V1=?

V3=?

V2=?

V1 240vV2 415vV3 240vV4 = 0V

What should the voltage be?

V4=?

240v

240v240v

240V

415v

240V240V

240V

240v

240v

415v

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Minimum records that should be completed and maintained

• A record of the inspection and test results. • A record of faulty electrical equipment (has it been repaired

or destroyed).

Date of inspection

Appliance Visual inspection

Earth continuity

Insulation resistance

M

Polarity = Correct

RCD test current

30 MA trip timeMilliseconds

0 180 Test butt

2/7/10 Refrigerator ( LG model R100020 Serial 1004039832)

O.K 0.3 75M N/A N/A N/A N/A

2/7/10 Safetypac (Clipsal mod 56B, serial 9987987)

o.K. 0.8 187M 22 18

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Energising supply• Only after the visual inspections and safety testing as per

AS/NZS 3000:2007 has proven that the circuit is fit for purpose are you to energise the circuit.

• Remove only your Danger tag. If another worker has their danger tag on the isolated point then you can not energise.

• If clear: Energise the circuit.• Test for the correct and safe operation of the circuit, i.e.

rotation, system performance, current draw, voltage, etc.• Prepare all your safety and performance documentation.

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