Arc Flash Hazards and Protection - Safety Services New Brunswick

Arc Flash Hazards and

Protection

2013 Heath and Safety Conference

Arc Flash Hazards and Protection

Presentation SummaryArc Flash HazardsStandards and RegulationsArc Flash CalculationsArc Flash ProtectionArc-Rated PPENB Power Update

Arc Flash Hazards

What is an Arc Flash HazardA dangerous condition associated with the possible release of energy caused by an electric arc. (CSA Z462-12)

Arc Flash Hazards

What is an Electric ArcAn electric arc is a short circuit through air

Arc Flash Hazards

How can an Electric Arc occur?Dust, impurities, corrosion, condensation, animalsOver-voltages across narrow gapsFailure of insulating materialsEquipment failureSpark discharge from accidental touching, dropping tools with human interaction

Arc Flash Hazards

What are some of the hazards associated with an arc flash incident?

High TemperaturesMolten MetalPressure WavesSound WavesShrapnelIntense Light

Pressure Waves

Copper Vapor:Solid to VaporExpands by67,000 times

Molten Metal

Intense Light

Hot Air-Rapid Expansion

35,000 °F20,000 °C

Shrapnel

Sound Waves

Arc Flash Hazards

What are some of the injuries that may result due to an arc flash incident?

BurnsBlindnessBlast InjuriesShockHearing Loss

Arc Flash Hazards

What are the factors that contribute to the intensity of the energy released by an electric arc?

What is the Available Fault Current?Is the electric arc occurring in an enclosure or in open air?How long will the worker be exposed to the flash? In other words, what is the time to trip?How far will the worker be from the electric arc?

These are the major factors, but there are others such as arc length, voltage, number of phases, arc motion, grounded fault, etc…

Arc Flash Hazards

What is the term that describes the intensity of the energy released by an electric arc?

INCIDENT ENERGYthe amount of energy, impressed on a surface a certain distance from the source, generated during an electrical arc event. (CSA Z462-12)

The unit of measure is sometimes in cal/cm2

Arc Flash Hazards

Why now?Electricity has been around since the late 1800’s – why is this topic been so popular over the past few years?

Arc Flash Hazards

Why now?INVENTION OF THE CAR - SEATBELT

1769 – first self-propelled car which could attain speeds of up to 6 km/hr1771 – another steam-driven engine which ran so fast that it rammed into a wall, recording the world’s first accident 1807 – design of the first internal combustion engine 1860 – the first successful two-stroke gas driven engine 1885 – the four stroke engine was devised1908 – The Ford Motor Company launched the Model T Ford1955 – Ford offered for the first time lap belts as an “option”1956 – Seat Belts offered in a safety package1964 – Most cars were sold with standard front seat belts 1968 – Rear seat belts were made standard 1970 – the state of Victoria, Australia, passed the first law worldwide making seat belt wearing compulsory for drivers and front-seat passengers – but not rear.1983 – Seat Belts regulated in New Brunswick – with exceptions

…about 200 years after the first car

Arc Flash Hazards

Why now?Comparing the car to the invention of electricity and the seatbelt ….to arc flash protectionSimilar to the regulations of the seat belt protecting against car accidents, it has taken us a few years to establish proper PPE against arc flash hazards

1881 – The first public electricity was delivered in 1881.1882 – New York first large scale distribution 18821884 – The first turbine was in 1884.1884 – Electricity distributed in Saint John in 18841886 – Electricity distributed in Moncton 1886 1887 – Electricity distributed in Fredericton 18871920 – NB Power formed in 1920

…it wasn’t until 1984 when the hazards of arc flash was first documented.

Standard and Regulations

History Summary1969 – research was conducted on burn victims and determine the level of heat energy (later to be termed IE) the onset of a second-degree burn (1.2 cal/cm2)

1976 – NFPA formed a committee at the request of OSHA to develop a electrical safety standard. The NFPA-70E was first published in 1979.

1982 – The first documented paper on arc flash hazards was published by Ralph Lee. “The Other Electrical Hazards, Electric Arc Blast Burns”

1991 – OSHA included the term “Arc Flash” as an additional hazard to the shock hazard of electricity.

1992 – At the request of ASTM F18 Committee Task Force on Electric Arc Test Method Development, Duke Power developed software to predict arc incident energy.


History Summary1992 – OSHA added the statement that the clothes worn by the worker must not increase the extent of the injury should the worker be exposed to arc flash on the job

1995 – Arc Flash Hazard was included in the 1995 edition of the NFPA 70E. This was the beginning of “standards” formally attempting to address this electrical hazard.

1997-2000 – Research and testing performed on protective clothing

2000 – NFPA-70E updated based on this research and the HRC were introduced

2002 – IEEE 1584 was published providing methods to complete calculations for predicting Incident Energy.

2002 – NEC acknowledges the arc flash hazard and introduced 110.16 Flash Protection. This article requires marking of certain electrical equipment to provide warning.


History Summary2006 – CEC was update to include awareness of Arc Flash Hazards. Rule 2-306 requires a sticker to warn personnel of hazard of shock and now arc flash.

2009 – The 2009 edition of the National Electrical Safety Code (NESC) requires that, effective Jan. 1, 2009, electric utility systems that fall under this standard must perform an arc flash assessment.

2009 – CSA joins forces with NFPA-70E. CSA publishes Z462 – Workplace Electrical Safety in January 2009 to establish the first electrcial safety program standard in Canada. (newest update in 2012)

2010 - Since both the NFPA-70E and CSA Z472 exclude all installations under the exclusive control of an electric utility, CEA (Canadian Electrical Association) brought together utilities across Canada to develop and approve CN/ULC S801-10 –Standard on Electric Utility Workplace Electrical Safety for Generation, Transmission, and Distribution.


Summary – National StandardsNFPA-70E – is an American standard providing best practices for a safe electrical program for the industrial sectorCSA Z462 – is the Canadian version of the NFPA-70EULC S801 – is a Canadian standard providing best practices for a safe electrical program for utilities

All of these standards outlines safe practices when working around electricity.

All of these standards have a section that provides information about protecting workers against electrical arc hazards.


Regulations - United StatesUtilities - NESC: Effective January 1, 2009, the employer shall ensure that an assessment is performed to determine potential exposure to an electric arc for employees who work on or near energized parts or equipment. If the assessment determines a potential employee exposure greater than 2 cal/cm2 exists, the employer shall require employees to wear clothing or a clothing system that has an effective arc rating at least equal to the anticipated level of arc energy.Industry - OSHA: The employer shall ensure that each employee who is exposed to hazards from electric arcs wears clothing with an arc rating greater than or equal to the heat energy estimated under paragraph (l)(11)(ii) of this section.


Regulations – New Brunswick

OHSA Regulation 91-191 - 287.4(1) Where it is not practicable to de-energize electrical equipment before working on or near energized exposed parts of the equipment, an employee shall use rubber gloves, mats, shields and other protective equipment to ensure protection from electrical shocks and burns while performing the work.


In summary…

OHSA – Regulation 91-191 states that an employer shall protect employees against electrical burns.

…andThere are national standards that now provide direction and methods to protect workers against arc flash hazards

QUESTION: Where do we start?

Arc Flash Calculations

Arc Flash AssessmentsCSA Z462 - If energized electrical conductors or circuit parts operating at 50 V or more are not placed in an electrically safe work condition, other safety-related work practices shall be used to protect workers who might be exposed to the electrical hazards involved. Such work practices shall protect each worker from arc flash…. Appropriate safety-related work practices shall be determined before any person is exposed to the electrical hazards involved by using both shock hazardanalysis and arc flash hazard analysis.

ULC S801 - When workers are required to work on or near energized equipment above 240 V a.c. and sources greater than 125 kVA, an arc flash assessment should be performed in order to determine the potential incident energy of an arc flash for the specific equipment.


Arc Flash Assessments will determine:

INCIDENT ENERGYThe PPE that is required when working within the boundary.The distance a worker is required to be with no additional PPE if exposed to energized equipment (in regard to an arc flash)


Available Method of Calculations:

Lee’s MethodDuke Power Heat FluxNFPA-70E (Doughty)ARCPRO (Kinetrics)IEEE 1584


Available Method of CalculationsMethod Voltage Ibf KA 1 or 3 Arc Gap

Clearing Time

Fault in Air

Fault in Box

Lee’s Method

Unlimited Unlimited 1 ** No Limit Y

Duke Heat

Not Published

Not Published

1 *Greater

than 1 **No Limit Y

NFPA-70E

< 600V 16 to 50 3 1.25 No Limit Y

ARCPROTo sustain

Arc3.5 to 21.5 1 * 1 – 12 No Limit Y Y *

IEEE 1584

208V to 15KV

0.7 to 106 3 0.5 - 6 No Limit Y


General Assessment Procedure:Select the model to complete calculations

Determine the bolted fault current

Calculate the arcing fault current (if required)

Determine the trip time of the protective device based on the arcing fault current.


General Assessment Procedure:Note other variables such as the voltage, arc gap, working distance.

Calculate the INCIDENT ENERGY

Determine the required PPE

Document the results.

After an arc flash hazard analysis has been completed, additional engineering may be required to lower the IE to manageable levels


In Conclusion:

There are a number of tools to calculate Incident Energy

Industry seems to be using IEEE-1584 for <15KV in-a-box 3-phase small gaps and Arcpro for high voltage in air single-phase longer gaps

Understand the applications and limitation of existing models


Just remember…

CALCULATING THE INCIDENT ENERGY OF AN ELECTRIC ARC

IS NOT A PERFECT SCIENCE

Arc Flash Protection

What do we need to protect from?


What do we need to protect from?

INCIDENT ENERGY


How can we protect workers against IE?



1. Arc Flash Assessment



1. Arc Flash Assessment2. Engineering Controls



1. Arc Flash Assessment2. Engineering Controls3. Administrative Controls



1. Arc Flash Assessment2. Engineering Controls3. Administrative Controls4. Implement the appropriate PPE

Arc-Rated PPE

Arc-Rated PPE

How do you know if you have the correct PPE?

Arc-Rated PPE


PPE for Arc Flash Protection is given an

ARC RATING

ARC RATING is a value expressed in cal/cm2 that describes the performance on an exposure to an electrical arc discharge.

Arc-Rated PPE


PPE for Arc Flash Protection is given an

ARC RATING

ARC RATING is typical labelled as the Arc Thermal Performance Value (ATPV) or the Energy of Breakopen Threshold (Ebt)

Arc-Rated PPE


Arc-Rated PPE

What is an Arc-Rating?

Arc-Rated PPE

What is an Arc Rating?

Arc RatingASTM F1959

Flame Resistant ASTM D6413

Garments ASTM F1506Face Shield ASTM F2178 Rain Wear ASTM F1891

Arc-Rated PPE


ARC RATING > INCIDENT ENERGY

Arc-Rated PPE

How do you know if you have the correct PPE?CSA Z462 created Hazard Risk Categories

Incident Energy

(Cal/cm2)

Category

(CSA Z462)

Requirements as per CSA Z462

< 1.2 HRC 0 Non-melting clothing, Hard hat, safety glasses, gloves, hearing protection,

1.2 4 HRC 1 Arc-Rated Clothing, Hard hat, safety glasses, gloves, hearing protection, Face shield

4 8 HRC 2 Arc-Rated Clothing, Hard hat, safety glasses, gloves, hearing protection, Face shield and balaclava

8 25 HRC 3 Arc Flash Suit with minimum arc rating of 25

25 40 HRC 4 Arc Flash Suit with minimum arc rating of 40

Arc-Rated PPE


Arc-Rated PPE


PPE Arc Rating shall be greater than ATPV of 26.5

Using HRC, this IE would mean we would protect

with HRC 4

Arc-Rated PPE


Arc-Rated PPE


PPE Arc Rating shall be greater than ATPV of 4.6

Using HRC, this IE would mean we would protect

with HRC 2

Arc-Rated PPE


…and attempt to make reasonable rules for your workers while protecting them.

ARC RATING > INCIDENT ENERGY

NB Power Update

NB Power Update

Arc-Rated PPE OPTIONS

If Incident Energy is known

Meets or exceeds CSA Z462 Hazard

Risk Category

A < 1.2 cal/cm2 0

B 1.2 to 4 cal/cm2 1

C 4 to 8 cal/cm2 2

D 8 to 40 cal/cm2 3 and 4

NB Power Update

OPTION AIf known, this option will provide adequate protection for Incident Energy < 1.2 cal/cm2.

This option will meet or exceed CSA Z462 HRC 0

NB Power Update

OPTION BIf known, this option will provide adequate protection for Incident Energy 1.2 to 4 cal/cm2.


Add an Arc-Rated face shield

NB Power Update

OPTION BIf known, this option will provide adequate protection for Incident Energy 1.2 to 4 cal/cm2.


NB Power Update

OPTION CIf known, this option will provide adequate protection for Incident Energy 4 to 8 cal/cm2.


Add an Arc-Rated balaclava

NB Power Update

OPTION CIf known, this option will provide adequate protection for Incident Energy 4 to 8 cal/cm2.


NB Power Update

OPTION DIf known, this option will provide adequate protection for Incident Energy 8 to 40 cal/cm2 .

This option will meet or exceed CSA Z462 HRC 3 or 4


Summary:Implemented Standard June 2012Clothing program for electrical workersContinue re-enforcing of standard and rules

NB Power Update

Hurdles - in my opinion…Completing studies Implementing new PPE – which way do we go?Clothing – everyone has an opinionLong Sleeve shirts in the summerFace Shield and Flash Suit new to workers

Questions


Thank You

Arc Flash Hazards and Protection - Safety Services New Brunswick

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