IDC Technologies Recent changes to arc flash standards and ... · IDC Technologies: Recent changes to arc flash standards and hazard reduction equipment Arc Flash & Isolation Safety

IDC Technologies: Recent changes to arc flash standards and hazard reduction equipment

Arc Flash & Isolation Safety Conference - Perth 2015 1

IDC Technologies

Recent changes to arc flash standards and hazard reduction equipment

Brett Cleaves

Director / Principal Engineer, Engineering Safety

Abstract

The recent release of ENA NENS 09 2014 sends a clear message that cotton PPE is not suitable for electrical workers, and electrical workers should wear a minimum of 4cal/cm2 arc rated PPE on the arms, legs and torso, with higher levels of PPE for higher risk tasks on higher risk equipment.

Introduction

Arc flash standards have been evolving since the 1980’s. The research that precedes or follows each step of the evolution has greatly improved the understanding of arcing faults and their associated hazards. Likewise, equipment manufacturers have continued to developing products to help to control the hazards. Since 2002 IEEE 1584 has been the benchmark standard for quantifying arcing hazards in terms of incident energy. Continued research has highlighted a number of shortcomings in the standard, many of which are being addressed as part of the standards ongoing major revision.

With known issues in the current Australian and International standards, and with probably the largest electrical workforce in Australia, Sydney metropolitan electrical utility Ausgrid recently initiated a process to review arc hazards and available PPE. Armed with the available information including research by Australia’s own Dr David Sweating, and its own Lane Cove testing station, Ausgrid commenced testing. The test adopted a horizontal bus bar arrangement that places the test dummy directly in the line of fire of the arcing fault and its products. The focus of the testing was to update the Ausgrid arc flash safety program, which in turn became part of the NENS 09 review and form the basis of the new heavily revised ENA NENS 09 2014 National Guideline for the Selection, Use and Maintenance of Personal Protective Equipment for Electrical Arc Hazards.

ENA NENS 09 2014

The ENA is a power industry group representing Australian electrical and gas utilities. The NENS 09 Guideline applies to workers within the electrical supply industry who are required to work on or near low and high voltage electrical apparatus.

The single largest change in this version is that cotton PPE is out and arc rated PPE is in. The latest version incorporates the results of extensive testing and reasoning by Ausgrid’s Mr Darren Jenkins, as well as his peers and the NENS 09 committee. The testing behind NENS 09 confirms that the opposing electrode arrangement used in IEEE1584 and the position of the calorimeters used to measure the energy resulted in IEEE1584 understating the energy as



seen by the body by a factor of 3 compared to a horizontal parallel three phase bus configuration.

As well as being more representative of real life switchboard and MCC scenarios, and in addition to the radiant heat the horizontal arrangement directs (by Lenz’s Law) the arc products (plasma cloud, molten metal etc.) directly at the test dummy and sensors. The opposing electrode configuration utilised in IEEE1584 predominantly exposes the test dummy and sensors to the radiant heat from the arc. The picture below combines figures from NENS 09 to illustrate the difference between the energy received to the end and to the side of the electrodes.

The test results further confirm the research by others that the plasma cloud from horizontal conductor arrangement employed in switchgear increases the incident energy that the victim is exposed to. The resultant energy from the tests is a factor of arc current, duration, distance and direction.

The geometry of the equipment, the shape and size of people, the position of their limbs and bulk all play a role in any potential injuries. Predicting the energy from an arc fault in in many ways is like cutting the end of a fire hose off and trying to predict how wet you will get. With that in mind, the recommendation is that the predicted incident energy should be used as just one of the inputs into your arc hazard risk assessment processes that will be discussed later.

For those implementing, or considering the implementation of an electrical workers PPE policy NENS 09 is a comprehensive guide to the selection of electrical workers PPE covering the base level of PPE, undergarments, fabric, weave, garment construction, and garment design. Also included are sections on protection for the head, hands and feet.

The single most important take home message from NENS 09 is to get out of cotton as your electricians everyday clothing and wear a minimum 4cal/cm2 arc rated PPE on the arms legs and torso, with higher levels of PPE for higher risk tasks on higher risk equipment.

The minimum rating is important to note. The tests revealed lots of information regarding the effects of an arc fault on a wide range of arc rated and non-arc



rated PPE, and while the realised incident energy was measured at levels 3 times higher than predicted by IEEE1584 the clothing also performed better than expected.

Unfortunately the driver for the tests was identifying the PPE required for the utility and while the results were worthy of a PhD, the process has not completed the loop by developing an associated PPE testing standard. Like AS4836 and NFPA70E, NENS 09 still require people to perform an arc flash hazard assessment help to identify and implement controls to reduce the likelihood and severity of an arc incident. This is where the latest version of NFPA70E provides the end user with some extra assistance.

NFPA70E 2015

Earlier versions of the American arc rated suite of standards resulted in thousands of electricians around the world moving away from plain cotton or worse and into arc rated PPE. With arc rated PPE developing quickly to match the standards the focus tending to fall on PPE to manage the hazard. Electrical consultants, myself included have been asked to perform an arc flash hazard analysis of the installation and provide the labels for each panel so that the electricians can wear the required level of PPE as required by the standard and the analysis. Fortunately, the latest version of NFPA70E focuses more attention on utilising the hierarchy of controls to eliminate or reduce the potential impact of the hazards.

The standard includes task and equipment based tables to enable users to identify which tasks require PPE, and what level of PPE is required. The tables have limitations on fault level, voltage, and clearing times that require some level of engineering to establish. The clearing time restrictions generally rule out the use of the tables for at least some of the equipment onsite. Previously the standard allowed both techniques to be utilised on a given installation. The new standard does not allow a mix of the table and the calculation methods.

The standard also now provides much clearer information on the impact of doors on metal clad switchgear and the available incident energy. Previously having a door closed did not enable you to reduce the required PPE for the prospective incident energy inside the unit. The end result was that people were suiting up to complete operating tasks on closed metal clad equipment which had been built and maintained to standards designed to protect the operator. The standard now states that normal operation of equipment is permissible if all of the following conditions are satisfied in accordance with the relative codes, standards and manufacturers recommendations:

The equipment is properly installed.

The equipment is properly maintained.

The equipment doors are closed and secured.

All equipment covers are in pace and secured.

There is no evidence of impending failure.

When doors are required to be opened and closed for normal operation, the standards technical committee advises that the door is not sufficient protection. Such operations could include racking in and out circuit breakers. If your equipment meets all of the above criteria then normal operating of the



equipment is permissible without any arc rated PPE. For electricians who are required to open the door for proving de-energised, test before you touch, or other testing and fault finding then depending on your risk assessment arc rated PPE may be required.

There is of course much more information with respect to arc hazards contained in the standard and its informative annexes. The electrical hazards and controls described in NFPA 70E are not limited to arcing fault hazards and only some of the changes in the latest revision are touched on above. When used in combination with AS4836, NFPA 70E helps to provide more detail to assist companies to complete their hazard risk assessments and further develop their safe working practices.

What do these changes mean for Australians

With the release of ENA NENS 09 Australia finaly has a guideline outlining Arc Rated PPE for everyday use by electrcial workers. The minimum level of 4 Cal/cm2 is at the low end of the available garments ratings, meaning there are numerous fabric options available for companies to choose from. NFPA 70E previously led companies towards a minimum 8 Cal/cm2 clothing for everyday wear. This resulted in some of the fabric manufactureres developing their lowest weight options to achive the higher rating resulting in garments that are slightly warmer to wear than the current cotton drill garments required by most mining, heavy industry, contruction and utility companies. The marginal increase in weight and warmth of the clothing is the major reason for pushback from Australian electricians.

The results of all of the testing in Australia and overseas are undeniable. When faced with even low level arc hazards cotton clothing can catch alight. When it does the results can be devestating. The initial burns form the arc incidnet are compounded by the continued burning of the clothes increasing the severity and surface area of the burns. This reduces the likilyhood of survival and increasing the pain and length of any form of recovery. In short the cotton PPE increases the likilhood of seriuos injury of death when compared to arc rated garments.

With respect to arc hazrads low voltage is almost always more dangerous than high voltage. The high prospective fault levels and lengthy fault clearing times can combine to produce dangerously high prospective incidnet enrgy levels. The high frequency of interaction with Low Voltage equipment and at times little to no maintennce also means that you are statistically more likely to have an incident. As a result of incidnts many Autralian companies including the big miners implimented the blanket use of Arc Rated flash suits and hood for all high voltage operating work. While a step in the right direction, it worked to propogate the myth that low voltage was safer. Across the country electricans are currently suiting up to perform High Voltage operating work and taking the suit and hood off before walking into the room next door to work on LV equipment, often with more than double the prospective incidnet enrgy. The next edition of Industrial Electrix will include case studies highlighting the elevated incident energy levels on low volatge systems for a large ore handling facility and for a smaller distribution transformer fed factory.

PPE is the least favourable and lowest form of hazard control, but it should not place the worker at greater risk of serious injry or worse. From Nens 09 and



generally speaking the minimum PPE required by an electrician until a safe state can be established and verified via test before you touch is:

Arc Rated Long Sleeve Shirt buttoned at the wrist

Arc Rated Long Pants

Arc Rated Face Shield with chin return

Leather gloves, or voltage rated gloves with leather outers

Safety Glasses

Leather Safety Boots

Obviuosly Other controls that eleiminate the need for tasks on energised equipment, reduce the fault levels and or protection operating times for equipment and the required procedural changes to improve the work practices are also required. These controls are discussed in the following paper.

About the Author

Brett Cleaves is the founding director of Engineering Safety and has over 20 years enginering experience in heavy industry and electrical utilities including 10 years in Arc Flash hazard analysis and controls. For contact information refer to www.engineeringsafety.com.au

Your logo here

Arc Flash Standards and What it Means for Australian Work

Places

Brett CleavesDirector / Principal Engineer, Engineering Safety Pty Ltd

November 2001

November 2001

But we don’t do live work!

All electrical tasks have the potential for exposure to Arc

Hazards

Stage 1 - Creating a Safe Work Situation

• Operating Work for Isolation

• Isolation Verification

• Lock out / Tag Out

Stage 2 – Work

• Test Before You Touch

• Work related tasks

• Pre-commissioning

Stage 3 - Restoration

• Commissioning

• Operating Work

Unplanned work generally involves fault finding and testing

Electrical Safety Codes of Practice

“A person conducting a business or undertaking has the

primary duty under the WHS Act to ensure, so far as is

reasonably practicable, that workers and other persons at the workplace are not exposed to electrical risks arising

from the business or undertaking. This duty requires

eliminating electrical risks or, if that is not reasonably

practicable, minimising the risks so far as is reasonably

practicable”

Electrical Safety Codes of Practice

“What are Electrical Risks…..arcing, explosion or fire

causing burns. The injuries are often suffered

because arcing or explosion or both occur when high fault currents are detected”

AS3000:2007 Wiring Rules

“ Protection against arcing fault currents while the

equipment is in service, or is undergoing

maintenance, shall be provided for heavy current

switchboards”

“Heavy Current are those where the nominal supply

current to the switchboard is 800 A or more per

phase”

AS4836:2011 Safe working on or near low-

voltage electrical installations and equipment

..”minimum set of procedures, safety requirements

and recommendations to manage the hazards

associated with electricity specifically arc blast,

arc flash, electric shock”…

AS3007:2013 Electrical equipment in mines and

quarries – Surface installations and associated

processing plant

”2.8.5 Arc flash/blast protection Design shall

include provisions of arc flash/blast injury…For

information on arc flash/blast protection, see IEEE 1584 and NFPA 70E”

IEEE 1584 – 2002 Guide to Performing Arc Flash

Hazard Calculations

NFPA 70E – 2015 Standard for Electrical Safety

in the Workplace

• Now includes the Hierarchy of Controls rather

than focusing on PPE

• Provides task based table for PPE selection

• Includes arc flash PPE lookup table based on

prospective bolted fault current and fault clearing

time.

• Describes the Calculation Method (IEEE1584)

• Prohibits the use of both methods in a given

installation

NFPA 70E 2015 – Tasks Not Requiring Arc Rated

PPE

• Reading Meters and operating meter selection

switches

• Normal operation of a circuit breaker switch

contactor or starter when:

– The equipment is properly installed

– The equipment is properly maintained

– All equipment doors are closed and secured

– All equipment covers are in place and secured

– There is no evidence of impending failure

• Thermography outside restricted approach

boundary. Note this activity does not include

opening doors and covers

NFPA 70E 2015 Arc Flash Hazard PPE CategoriesEquipment Arc Flash

PPE

Category

Arc Flash Boundary

Panel boards or other equipment rated <240 V and up to 600VParameters:

Max 25 kA short-circuit current

Max 0.03 sec (2 cycles) fault clearing time

Working Distance 455 mm

2 485 mm

600 V class motor control centresParameters:




2 1.5 m

600 V class motor control centresParameters:




4 4.3 m

600 V class switchgearParameters:




4 6 m

17

Nov 2011

Shirt• Orange for easy recognition• 260gsm Weight • ATPV 9.5Cal/Cm2

• High wrap around collar• H Pattern – FR reflective tape

• Closed front• Closed Gusset• ATPV rating Embroided onto shirt and pants• Replaces 4.4 Cal/cm2 PR97 Shirt

Pants• 300gsm Weight • ATPV 12.8Cal/Cm2

• Cargo Pockets on Both Legs• Replaces Cotton Drill Pants

ENA NENS 09 – 2014 National Guideline for the

Selection, Use and Maintenance of Personal

Protective Equipment for Electrical Arc

Hazards

…“PPE forms part of the Hierarchy of Controls and

this document provides guidance for the selection

of appropriate PPE for electrical arc hazards.”

ENA NENS 09 – 2014 National Guideline for the

Selection, Use and Maintenance of Personal

Protective Equipment for Electrical Arc

Hazards

…“PPE forms part of the Hierarchy of Controls and

this document provides guidance for the selection

of appropriate PPE for electrical arc hazards.”

ENA NENS 09

“Base Garments manufactured from arc rated

materials should be worn where there is the

possibility of exposure to incident energy of

5 J/cm2 (1.2 cal/cm2) or above.

The recommended minimum ATPV for base garments is 16.7 J/cm2 (4 cal/cm2)”

Preventative

Controlsto stop the incident occurring

Mitigating

Controlsto reduce the consequence

Electrical Safety System

Com

mon C

auses

Consequences

Electrical Shock or

Arc Blast-Flash

Standards

Communication

Safety Culture

Maintenance

TBYT

Training

Inspections Audits

PoliciesProcedures

Standards

Training

Protective Devices

Emergency Isolation Plan

Emergency Response

Safety Equipment

PPE

Incident Investigation

Isolation

Redundant Equipment

TaskUnfamiliarity

Hazard Identification

Incorrect Isolation

Equipment not f it for Service

EquipmentUnfamiliarity

Labelling

Short Cuts

Equipment not fit for Duty

Eliminate

Substitute

Isolate

Engineering

Administration

PPE

Substitute - Low Fault Level Test Points

Substitute – Remote Operation

Substitute – Delayed Operation

Engineered Controls

• Modified Protection Settings

• Maintenance Protection Setting Mode

• Arc Fault Detection

• Zoned interlocking

• Position of Protection CT’s

• Voltage Indication

• Castel Interlocking

• Arc Fault Suppression Devices

Administrative Controls – Task Requiring Full

Isolation

• The removal of busbar covers


Isolation

• The removal or insertion of bolts or screws that enter blind holes in backplates, equipment mounting plates, etc.


Isolation

• All drilling except on an open door where both sides can be seen


Isolation

• Working on top of or above switchgear


Isolation

• Construction or long duration tasks around or above transformers


Isolation• Any activity (except operating work) on any isolating device where the

incoming side is still live


Isolation

• The removal of busbar covers

• Any work on the incoming side busbar system or anything directly connected to it

• The removal or insertion of bolts or screws that enter blind holes in

backplates, equipment mounting plates, etc.

• All drilling except on an open door where both sides can be seen

• Metal work modifications where both sides of the panel cannot be seen

• Pulling- in and termination of cables in compartments with exposed conductors or terminals

• Disconnecting and re-terminating of cables in compartments with exposed conductors or terminals

• Blowing out any of this equipment

• Any activity (except operating work) on any isolating device where the incoming side is still live

• Working on top of or above switchgear

• Construction or long duration tasks around or above transformers

Arc Rated Electrical Workers PPE

PPE is part of the solution and in many circumstances

cannot be engineered out.

Cotton PPE burns and increases the injuries of the

worker it was supposed to protect.

As a minimum the recommendations in ENA NENS 09

should be adopted for all electrical workers

Documents

IDC Technologies Recent changes to arc flash standards and ... · IDC Technologies: Recent changes to arc flash standards and hazard reduction equipment Arc Flash & Isolation Safety