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Arc thermal performance value (ATPV) is a measurement of a fabric’s ability to protect an individual from a burn due to exposure to incident energy resulting from an arc flash.

Specifically, the ATPV of a fabric refers to the amount of incident energy necessary for there to be a 50% probability that an individual wearing that fabric would suffer a second-degree burn if exposed to an arc flash at the point of the worn fabric.

The ATPV is one of the two values used to determine the arc rating of a piece of personal protective equipment (PPE). The other value is energy break-open threshold (EBT). The ATPV and EBT of a fabric must be tested as part of its arc-rating process. The lowest value of the two (the ATPV or EBT) issued as the arc rating of the PPE under consideration, as this value reflects the point at which the clothing’s protective capacity is likely to fail.

To ensure that PPE meets an employer’s legal requirement to provide employees with appropriate PPE in situations requiring arc-rated PPE, the PPE used must have been tested in compliance with standards put forth by either ASTM International or the International Electrotechnical Commission(IEC). ASTM standards are used to test PPE for use in the United States, whileIEC standards are used for the same purpose in Europe. The above standards organizations describe how fabric must be tested to determine its ATPV according to ASTM F1959 and IEC 61482-1, respectively. A fabric’s energy break-open threshold is determined using the same test and standard.

Arc-rated clothing that complies with ASTM or IEC standards may not show the ATPV if it is higher than the EBT value. ATPV and EBT are held to be equally protective to workers

While both values (ATPV and EBT) can be reported, only one arc rating is given to fabric.

Only the lowest value will be used on the clothing label according to ASTM F1506 specification.... EBT fabrics are typically more insulative than they are strong, and generally ATPV fabrics are stronger than they are insulative.

When ARC Flash protective garments are worn together in a layered combination, the PPE may give you a total protection value that is higher than the sum of the individual value for each garment. This is due to the air gap between each layer of fabric which acts as an insulator and increases the protection.

This increased protection is useful to workers who need to gain additional protection where required for certain tasks.

The NFPA 70E guidance would give the best explanation of how layering your Arc & Flame Protective Clothing can give you a required level of protection:

HAZARD RISK CATEGORY
(or known as arc, hrc or ppe)

ARC/HRC/PPE Category: 1 = >= 4 (REQUIRED MINIMUM ARC RATING FOR PPE)

ARC/HRC/PPE Category: 2 = >= 8 (REQUIRED MINIMUM ARC RATING FOR PPE)

ARC/HRC/PPE Category: 3 = >= 25 (REQUIRED MINIMUM ARC RATING FOR PPE)

ARC/HRC/PPE Category: 4 = >= 40 (REQUIRED MINIMUM ARC RATING FOR PPE)

Note – an appropriately Arc Flash Helmet, Visor and Gloves are also required.

PPE Category 1: Minimum Arc Rating 4 cal/cm2

PPE CAT 1 represents the lowest level in which Arc Flash PPE s required. Requiring a single layer of arc-rated PPE, workers need the following clothing:

Required Clothing: Arc Flash Long Sleeve Shirt (orJacket) and Trousers or Arc Flash Coverall with minimum arc rating of 4cal/cm2

Required Face and Head Protection: Face Shield(with “wrap around” guarding…i.e balaclava) or Arc Flash Suit Hood

As Needed: Arc Flash Jacket, Rainwear, Parka, HardHat Liner

In addition to AR clothing, the following productsare required or to be used as needed:

Required Hand Protection: Heavy-Duty Leather Gloves

Additional PPE: Hard Hat, Eye Protection (Glasses, Goggles), Hearing Protection

Footwear: Leather Footwear (as needed).

If you need further support contact us at in info@strata-protection.com

ELIM: Energy Limit Value

Numerical value of incident energy attributed to a product, below which there is no data point with the amount of heat transmitted through the product reaching the Stall criteria or with the product exhibiting break open.

The ELIM of a material or material assembly (garment) is calculated from data points obtained from testing a set of test specimens, which are also used for the determination of the ATPV and/or EBT.

The ELIM attributed to a garment or garment assembly is either equal to or lower than the ELIM of the material or material assembly of which it is made, depending on whether the tested specimen(s) fulfil also additional visual design and performance assessment criteria

ELIM
(Average of the three highest values of the incident energy data points of the date. Set below the mix zone without break open and without reaching Stoll curve)

This is a more conservative calculation of risk, all results for calculating ELIM is taken below the 50% chance of a 2 degree burn according to the Stoll curve.

Easy and compressed explanation:

ELIM is the conservative calculation of risk of an electric arc. ELIM the maximum incident energy that a protective clothing can prevent against in a hazardous situation, with 0% probability of enough energy getting through the garment to cause a second-degree burn.

ELIM has been introduced because the opinion of EU was that 61842-1-1 could be in conflict with EU directive. According to directive, no standard can impose harm to a worker.

By this, ATPV/EBT imposes 50% probability that a worker will sustain second degree burn in electric arc exposure. This means that the worker will statistically have burns every other time.

It is this 50% chance that ELIM has eliminated.However, it is just exactly in this way of testing as defined in the IEC 61482-1-1 open arc testing.

How if it will affect the marked and the practical use in a risk assessment plan for electrical work in the EU is not 100% clear, but there is ongoing discussion about taking NFPA 70E arc flash risk assessment into the EN 50110 Operation of electrical installations standard.

LOI is a technical and scientific measuring method that defines the flammability. It is the minimum concentration of oxygen, expressed as a percentage that will support combustion of a polymer/fiber/textile. It is measured by passing a mixture of oxygen and nitrogen over a burning specimen and reducing the oxygen level until a critical level is reached.

Limiting Oxygen Index (LOI) is the parameter most frequently used to characterise the improvements in fire retardancy of protective fabrics.

A fabric described as treated will be made from fibres which aren’t flame retardant by their nature, but have had a chemical applied or have been through a chemical process to add the fire resistance to them.

If a fabric is inherently flame retardant, its ability to protect you from heat and flames comes from the fibres of the fabric themselves.

The very essence of the poloshirt, coveralls, trousers or jacket is – at its core – flame retardant because these properties are part of the polymer it’s made from.

It determines the Arc Protection Class Rating of the material or garment by using a constrained and directed arc: 

Class 1 offers protection against electric arc 4kA (168kJ) 

Class 2 offers protection against electric arc 7kA(320 kJ)

Class relates to the European IEC 61482-1-2 standard – Class 1 or Class 2: 
Class 1 offers protection against electric arc 4kA (168 kJ) 
Class 2 offers protection against electric arc 7kA (320 kJ).
Category can be related to the NFPA 70E categories.

ARC/HRC/PPE Category: 1 = >= 4 (REQUIRED MINIMUM ARC RATING FOR PPE)

ARC/HRC/PPE Category: 2 = >= 8 (REQUIRED MINIMUM ARC RATING FOR PPE)

ARC/HRC/PPE Category: 3 = >= 25 (REQUIRED MINIMUM ARC RATING FOR PPE)

ARC/HRC/PPE Category: 4 = >= 40 (REQUIRED MINIMUM ARC RATING FOR PPE)

All clothing with an arc rating (AR) is flame resistant (FR) butnot all FR clothing has an Arc Rating.  

FR was traditionally believed to be generically protective from flame at some level but this is not the case for some fabrics. AR indicates that a garment has an arc rating and the level of protection has been determined through testing.

Fabrics for personal protective garments are put through aVertical Flame Test to measure and observe the response of materials to heat and flame under controlled conditions.

There are two main reasons for wearing FR clothing:                   

Ignition – FR PPE is worn to protect against ignition in an arcflash hazard situation. When an arc flash ignites non-flame resistant clothing, the wearer can be badly injured from the burning garment.

A garment can continue to burn, increasing the extent of the injury to the wearer, and can even cause internal injuries including airway and lung damage in some cases.Wearing FR clothing helps to reduce burn injury and contains burns to the body surface directly related to the area of origin.

Insulation – Flame resistant clothing gives the wearer insulation from the higher degrees of burn (2nd and 3rd degree) through the garments and can lessen the impact on the area directly affected by the incident. 

Arc rating and flame resistant are two different things but are often confused because they go hand in hand. You can’t have an arc rating without the material being flame resistant.

According to the arc rating standards (ASTM F1506, ASTM F1959, IEC61482-2, IEC 61482-1-1 Method A and IEC 61482-1-1 Method B), it is a prerequisite that clothing flame resistant (FR) before it can even be tested to define its arc rating.

It is crucial that you read the labels of garments and equipment before buying and to specify a standard to meet. If an arc flash hazard is apparent, the AR label should be present on any PPE. Choosing a garment labelled FR will not be sufficient protection in an arc flash situation.

Arc Flash Protective Clothing should be worn when working on or near live or potentially live electricity.

In the event of an arc flash heat will transfer through Arc Flash clothing and in some cases, enough heat could transfer through to melt some synthetic materials resulting in a burn injury.

Never wear synthetic fabrics such as polyester, nylon, or spandex underneath your arc-rated clothing.

If your Arc Flash Clothing is made from inherent fibres e.g. modacrylic or aramids then you have an unlimited wash capability regardless of how the garment is or has been laundered. IF your Arc Flash clothing is constructed with majority cotton fibres with a chemical applied to give the Arc flash protection then you must follow the garment care labels VERY carefully. 

Treated garments typically have a life time on the number of washes that can be conducted before the chemical properties and protection have deteriorated, otherwise the washing with certain laundry softeners and bleaches will react with the chemical fabric protection causing a deterioration in protection offered.

By determining the maximum duration of a potential arc, the potential energy level from arc flash, whether it will take place in an open or enclosed space and the flash protection boundary within which PPE will be required, you can find out what PPE you will be required to supply and train staff on its correct use.

Determine PPE level

There are two basic methods of determining the arc rating: tables or incident energy calculations. NFPA 70E contains hazard category classification tables listing job tasks and voltage parameters, and shows the appropriate PPE rating and flash protection boundary for each.

Incident energy is a measure of thermal energy at a working distance from an arc fault. The unit of incident energy is cal/cm2. The working distance is the distance from where the worker stands to the flash location. The selected PPE arc rating shall be based on the incident energy exposure.

The arc flash boundary is the minimum “safe” distance from exposed energised conductors or circuit parts that has the potential for an arc flash.

The National Fire Protection Association (NFPA) uses four ArcFlash PPE Categories to classify ranges of arc flash hazards, and the corresponding requirements for Personal Protective Equipment (PPE).

The categories are one of the methods used in the current NFPA 70E standard to inform workers about the protection they need while working on energised equipment. The Arc Flash PPE Category system replaces the Hazard/Risk Category (HRC) system from the 2012 edition of the standard.

ARC Category: 1 = >= 4 (REQUIRED MINIMUM ARC RATING FOR PPE)

ARC Category: 2 = >= 8 (REQUIRED MINIMUM ARC RATING FOR PPE)

ARC Category: 3 = >= 25 (REQUIRED MINIMUM ARC RATING FOR PPE)

ARC Category: 4 = >= 40 (REQUIRED MINIMUM ARC RATING FOR PPE)

For most equipment, this is simply a label warning qualified persons that there is a potential arc flash hazard present.

Electrical Hazard (EH), Anti-Static & Electrostatic Dissipative (ESD) Safety Boots. 

Electrical hazard (EH) rated safety boots are ISOLATING safety boots meaning they provide a secondary source of protection for you from electric shocks or electrocution.

The difference in protection is that Electrical Hazard shoes reduce the possibility of electric shock or electrocution, while Static Dissipating and Conductive shoes reduce the possibility of static discharge and static shock.

See link to video here

A fabric's arc rating is a measure of the amount of energy that it can absorb before the energy penetrates or moves through it with enough force to carry a 50% probability of causing a second-or third-degree burn. The value of an arc rating is measured in units of calories/cm2.

While utilizing the hierarchy of risk controls, such as lock-out/tag-out procedures, to put equipment in an electrically safe work condition, those working on energised electrical equipment should always wear Arc Flash(AR)/flame resistant (FR) personal protective equipment (PPE) on a job site to help mitigate injuries

Doing work on or near energised, or potentially energised equipment, threatens employees with danger from electric shock/ electrocution and arc flash.

To protect themselves from injury, or even death, workers should wear Protective Personal Equipment (PPE) as their last line of defence.

When it comes to keeping your PPE clean, there are some things that you can do to both protect and prolong the life and shape of the garment(s).

• Do not use fabric conditioners (softener). It can coat the garment and compromise inherent Flame Retardant properties.
• Do not bleach. This will not affect inherent protection, but can reduce garment quality and appearance.
• Do not use detergent containing bleach, optical whiteners or very strong chemicals. We recommend using Non-Bio liquid detergent.
• Ensure all fastenings, zips etc are closed prior to washing.
• Wash STRATA® garments separately from other items of clothing.
• Wash STRATA® garments by type, i.e tops together.
• Do not wash light and dark coloured garments together.
• Wash at the recommended temperature as advised on STRATA® wash care label.
• Wash extremely soiled garments separately.
• Grease stained garments should be pre-treated before washing, dry cleaning can be more effective

For more information on our recommended washing instructions click here, alternatively, get in touch with us on live chat, or via email at info@strata-protection.com

Within the UK and Europe it is not explicitly stated that arc flash protective clothing is a legal requirement but there is a lot of guidance that would include the use of Arc Flash ProtectiveClothing and in a court of law it will be interpreted as being unlawful if adequate PPE was not provided when an arc risk is present.

Some references:

Healthand Safety at Work etc Act 1974 – legislation explained (hse.gov.uk)

The Enforcement Notices that cite the Health and Safety at Work Act refer to breaches of the following provisions:

2/1: It shall be the duty of every employer to ensure, so far as is reasonably practicable, the health, safety and welfare at work of all his employees.

3/1: It shall be the duty of every employer to conduct his undertaking in such a way as to ensure, so far as is reasonably practicable, that persons not in his employment who may be affected thereby are not thereby exposed to risks to their health or safety.

TheElectricity at Work Regulations 1989. Guidance on Regulations (hse.gov.uk)

The Enforcement Notices that cite the Electricity at Work Regulations refer to breaches of the following
Regulations:

4: (1) All systems shall at all times be of such construction as to prevent, so far as is reasonably practicable, danger.

(2) As may be necessary to prevent danger, all systems shall be maintained so as to prevent, so far as is reasonably practicable, such danger.

3) Every work activity, including operation, use and maintenance of a system and work near a system, shall be carried out in such a manner as not to give rise, so far as is reasonably practicable, to danger.

6: Electrical equipment which may reasonably foreseeably be exposed to–

(a) mechanical damage;

(b) the effects of the weather, natural hazards, temperature or pressure;

(c) the effects of wet, dirty, dusty or corrosive conditions; or

d) any flammable or explosive substance, including dusts, vapours or gases,

shall be of such construction or as necessary protected as to prevent, so far as is reasonably practicable, danger arising from such exposure.

14: No person shall be engaged in any work activity on or so near any live conductor (other than one suitably covered with insulating material so as to prevent danger) that danger may arise unless–

(a) it is unreasonable in all the circumstances for it to be dead; and

(b) it is reasonable in all the circumstances for him to be at work on or near it while it is live; and

(c) suitable precautions (including where necessary the provision of suitable protective equipment) are taken to prevent injury.

16: No person shall be engaged in any work activity where technical knowledge or experience is necessary to prevent danger or, where appropriate, injury, unless he possesses such knowledge or experience, or is under such degree of supervision as may be appropriate having regard to the nature of the work.

HSE - Mining: Mines Regulations 2014

11: The mine operator must ensure that—

(a) no person undertakes any work at the mine unless the person either is competent to do that work or does so under the instruction and supervision of some other person who is competent to give instruction in, and to supervise, the doing of that work; and

(b) no work is undertaken at the mine unless a sufficient number of persons are present who have the requisite competence to perform the tasks assigned to them.

15: The mine operator must—

(a) prepare and keep up to date a suitable written scheme for the systematic inspection, maintenance and testing of all electrical and mechanical plant and equipment at the mine, with a view to ensuring the health and safety of the persons at work in the mine;

(b) ensure that, where appropriate, suitable written reports are made of the inspections and that each report records significant defects and the steps taken, or proposed to be taken, to remedy them; and

(c) ensure that any proposed steps in a report are taken, provided they are appropriate.

The Management of Health and Safety at Work Regulations 1999 (legislation.gov.uk)

The Enforcement Notices that cite the Management ofHealth & Safety at Work Regulations 1999 refer to breaches of the following Regulations:

3: (1) Every employer shall make a suitable and sufficient assessment of—

(a) the risks to the health and safety of his employees to which they are exposed whilst they are at work; and

(b) the risks to the health and safety of persons not in his employment arising out of or in connection with the conduct by him of his undertaking,…..

Construction- Construction Design and Management Regulations 2015 (hse.gov.uk)

The Enforcement Notices that cite the Construction(Design and Management) Regulations 2015 refer to breaches of the followingRegulations:

25: (1) Where necessary to prevent danger, energy distribution installations must be suitably located, periodically checked and clearly indicated.

(2) Where there is a risk to construction work from overhead electric power cables—

(a) they must be directed away from the area of risk; or

(b) the power must be isolated and, where necessary, earthed.

(3) If it is not reasonably practicable to comply with paragraph (2)(a) or (b), suitable warning notices must be provided together with one or more of the following—

(a) barriers suitable for excluding work equipment which is not needed;

(b) suspended protections where vehicles need to pass beneath the cables; or

(c) measures providing an equivalent level of safety.

(4) Construction work which is liable to create a risk to health or safety from an underground service, or from damage to or disturbance of it, must not be carried out unless suitable and sufficient steps(including any steps required by this regulation) have been taken to prevent the risk, so far as is reasonably practicable.

Electricity at work: Safe working practices HSG85 (hse.gov.uk)

Page 14 Decide whether suitable precautions can be taken to prevent injury32 Providing the requirements above have been met, live working can still only be justified if suitable precautions are taken to prevent injury arising from the hazards identified in the risk assessment. The precautions should have been identified in the risk assessment and might include:

■ installing temporary insulation, protective enclosures, or screens toprevent parts at different potentials being touched at the same time;

■ using temporary barriers with warning notices affixed to keep unauthorised people away from the work area;

■ ensuring that adequate clearances are established and maintained when working near to live equipment (see Appendix 3 of the Memorandum andSection 729 of BS 7671:2008 (+A1:2011) for information on clearances). For work near live overhead power lines, see GS6 Avoiding danger from overhead power lines;13

■ making sure that workers understand the task and the system to be worked on(clarity of instructions is essential), are trained and experienced, and follow the correct procedures. They must be competent to realise their own limitations and know when to seek help;

■ providing lighting and working space that is adequate and free from trip hazards. Further details on lighting at work can be found in HSG38 Lighting at work;14

■ using robust and properly insulated tools (see BS EN 6090015);

■ using test instruments with insulated probes and fused leads (see GS38Electrical test equipment for use by electricians16);

■ maintaining tools and test equipment in good condition and replacing them if damaged;

■ storing tools correctly – horizontal surfaces and projections inside control cabinets should not be used – and ensuring that objects such as tools and bolts cannot fall onto exposed live parts;

■ avoiding lone live working. Quick action is needed in the event of an electric shock to disconnect the supply and give assistance, so it will usually be necessary to be accompanied by someone who is competent to make the system safe and avoid injury;

■ providing and using correct personal protective equipment (PPE) to reduce the risk of contact with live parts or earth, eg insulating gloves, insulating matting(see BS EN 61111:2009). If there is a risk of burns from arcing or flashover that cannot be avoided, consider the use of adequately rated, thermally insulating, flame-resistant PPE (including face/eye protection). PPE should be frequently inspected and replaced if damaged. Requirements relating to PPE are covered by the Personal Protective Equipment at Work Regulations 1992

Keeping electrical switchgear safe HSG230 (hse.gov.uk)

Electrical safety and you: A brief guide (INDG231(rev1)) (hse.gov.uk)

Electrical switchgear safety: A guide for owners and users (hse.gov.uk)

Avoiding danger from underground services HSG47 (hse.gov.uk)

Electrical test equipment for use by electricians GS38 (hse.gov.uk)

Safety in electrical testing at work (hse.gov.uk)

Arc flash protection (theiet.org)

BS 7671 -18th Edition - IET Wiring Regulations (theiet.org)

CHAPTER 13
FUNDAMENTALPRINCIPLES
131PROTECTION FOR SAFETY

131.1General

The requirements of this chapter are intended to provide for the safety of persons, livestock and property against dangers and damage which may arise in the reasonable use of electrical installations. The requirements to provide for the safety of livestock are applicable in locations intended for them.

In electrical installations, risk of injury may result from:

i) shock currents

(ii)excessive temperatures likely to cause burns, fires and other injurious effects

(iii)ignition of a potentially explosive atmosphere

(iv)under voltages, over voltages and electromagnetic disturbances likely to cause or result in injury or damage

(v)mechanical movement of electrically actuated equipment, in so far as such injury is intended to be prevented

by electrical emergency switching or by electrical switching for mechanical maintenance of non-electrical

parts of such equipment

(vi) power supply interruptions and/or interruption of safety services

(vii)arcing or burning, likely to cause blinding effects, excessive pressure and/or toxic gases

BS EN 61936-1. Power installations exceeding 1 kVa.c.. Common rules

IEC61482-2, Live working - Protective clothing against the thermal hazards of an electric arc

BS EN61243-3 Live working. Voltage detectors. Two-pole low-voltage type British Standards Institution

BS EN61010 Safety requirements for electrical equipment for measurement, control and laboratory use British Standards Institution

BS EN50110-1:2013 Operation of electrical installations. General requirements

In Europe any PPE sold must meet the requirements of the PPE directive89/686/EEC. This is implemented in the UK as part of the Personal Protective Equipment at Work Regulations (2002).

It details the categories that PPE conforms to and how their performance and production should be controlled. Arc Flash protective clothing is"Category III" PPE and must be type approved and the continuing quality of the product must be fully audited over the garment's life.

This is the regulation under which a CE mark may be issued. A CE mark may not be applied to Arc Flash clothing unless both Type Approval (Article 10)and an Assessment of production Quality (Article 11A or 11B). Without these documents Arc Flash PPE may not be sold.

Arc Flash clothing is now built to meet the requirements of several new and updated technical specifications and standards. The key ones being:

BS EN 61482-1-1 This Test Method covers the "open" or unconstrained arc testing of material and garments. The result of this testing is an "ArcRating", commonly given as an Arc Thermal Performance Value (ATPV) or Break open Threshold Energy (EBT50). This is usually given in units of calories per square centimetre (cal/cm2). The test method requires that BOTH materials and garments produced from them must be tested before they may be CE marked.This is the same method employed in ASTM F1959 for fabric in the USA.

BS EN 61482-1-2 This Test Method covers the "box" or constrained arc testing of material and garments. The result of this testing is a"protection class", either Class 1 (4000 Amps) or Class 2 (8000Amps). With only 2 basic levels this is a very coarse method of assessing arc protection and the UK technical committee responsible for these standards suggests BS EN61482-1-1 is the better test method. The test method requires that BOTH materials and garments produced from them must be tested before they may be CE marked.

IEC 61482-2 An international standard that hasn't yet been"harmonised" across Europe due to disagreements or misunderstandings about the way that the "arc rating" is calculated in EN61482-1-1 tests. IEC61482-2 is a technical specification that defines how to build Arc Flash garments. It does not cover hand wear, headwear or footwear.

BS EN ISO 11612 An international standard covering clothing that protects against heat and flame.The requirements of this standard provide a good foundation and construction guidelines for Arc Flash clothing and so should always be used. As with the Arc Flash test methods, completed garments should be assessed for performance not just the constituent fabrics. Code Letters are applied that define the type of heat and flame with which a garment has been tested.

BS EN 61482-1-1 This Test Method covers the "open" or unconstrained arctesting of material and garments. The result of this testing is an "ArcRating", commonly given as an Arc Thermal Performance Value (ATPV) or Break open Threshold Energy (EBT50). This is usually given in units of calories per square centimetre (cal/cm2). The test method requires that BOTH materials and garments produced from them must be tested before they may be CE marked.This is the same method employed in ASTM F1959 for fabric in the USA.

BS EN 61482-1-2 This Test Method covers the "box" or constrained arc testing of material and garments. The result of this testing is a"protection class", either Class 1 (4000 Amps) or Class 2 (8000Amps). With only 2 basic levels this is a very coarse method of assessing arc protection and the UK technical committee responsible for these standards suggests BS EN61482-1-1 is the better test method. The test method requires that BOTH materials and garments produced from them must be tested before they may be CE marked.

IEC 61482-2 An international standard that hasn't yet been"harmonised" across Europe due to disagreements or misunderstandings about the way that the "arc rating" is calculated in EN61482-1-1 tests. IEC61482-2 is a technical specification that defines how to build Arc Flash garments. It does not cover hand wear, headwear or footwear.

Arc Flash Standards & Test Methods

ASTM F1506: Standard Performance Specification for Textile Material for Wearing Apparel for Use by Electrical Workers Exposed to Momentary Electric Arc and Related Thermal Hazards. 

This is the governing ASTM Standard for Flame Resistant Clothing. The standard has two basic requirements:

A sample of fabric must self-extinguish with less than 2 second after flame and less than 6″ char length according to ASTM Test Method D6413. This flammability test applies to an initial sample and after 25 wash cycles.

The fabric must be tested for Arc Thermal Performance according to ASTM Test Method F1959. The results of the Arc Thermal Performance testing must be reported to the end user as an Arc Rating on a garment label.

Different colours of the same fabric do not need to be tested separately.

A garment that meets ASTM F1506 complies with OSHA 1910.269, NESC, and NFPA 70E. ASTM F1506 is a pass/fail standard with requirements for reporting additional information not considered for the pass/fail criteria. All garments compliant to ASTM F1506 must be labeled with a tracking code, a statement that the garment meets the requirements of ASTM F1506, the manufacturer’s name, size information, care instructions, fibre content and the arc rating

ASTM F1891: Standard Specification for Arc Resistant Rainwear: 

This is the governing ASTM Standard for Flame Resistant Rainwear. The following are requirements of ASTM F1891:

A sample of fabric must self-extinguish with <2second after flame and <6″ char length according to ASTM Test Method D6413.

In contrast to ASTM F1506, ASTM F1891 requires that each different colour of the same fabric be tested.

The fabric must be tested for Arc ThermalPerformance according to ASTM Test Method F1959. The results of the Arc ThermalPerformance testing must be reported to the end user as an Arc Rating on a garment label. Rainwear that meets ASTM F1891 complies with OSHA 1910.269. ASTM F1891 is a pass/fail standard with requirements for reporting information not considered for the pass/fail criteria. All garments that meet the requirements of ASTM F1891 must state so on a garment label.

Material must withstand water pressure of 30 psig without leaking. The seams of the rainwear must not exhibit any evidence of leakage when exposed to water at 3 psig for (2) two minutes.

Material shall have a trapezoidal tear resistance of 6 lbs. in the warp direction and 6 lbs. in the fill direction.

Materials attached to the rainwear shall be permanent and electrically non-conductive, and shall not degrade the performance of the rainwear.

Rainwear material shall be flame resistant and shall not melt and drip when tested in accordance with ASTM D6413-08 and shall exhibit no more than a 2 second after flame time and less than a 6” char length

ASTM F1958: Standard Test Method for Determining Ignitability forClothing by Electric Arc Exposure Using a Mannequin

The ASTM F1958 test method provides a way to visually evaluate finished garments, since the F1959 arc rating test uses small fabric samples, not complete garments. The manikins do not have thermal sensors under the garments, and they do not predict burn injury. This method is primarily used to provide a qualitative view of performance, especially for buttons, zippers, logos, trim, reflective tape, and other garment components or design features beyond the FR fabric itself

ASTM F1959: Standard Test Method for Determining Arc Thermal Performance(Value) of Textile Materials for Clothing by Electric Arc and Related Thermal Hazards

ASTM F1959 is the test method used to calculate quantitative results (arc ratings) for FR fabrics. Arc ratings are a measure of thermal protection provided by the fabric in an arc flash.

The purpose of this test method is to determine how much heat a certain fabric (or system of fabrics) will block from an electric arc before the onset of second degree burns for the wearer.

The amount of energy blocked by the fabric is reported as Arc Thermal Performance Value (commonly abbreviated as ATPV). The value is reported as Energy Break open Threshold (EBT) if the fabric breaks open before the onset of second degree burns is reached.

Heat Attenuation Factor (the percentage of total heat blocked by the fabric from reaching the sensor) is also determined.

Test results from ASTM F1959 must be reported for all garments that meet ASTM F1506 or ASTM F1891.Additionally, ASTM F1959 is used to determine a pass/fail criteria for ASTM F1891.

NFPA 70E: Standard for Electrical Safety in the Workplace

OSHA 1910.269: The Operation and Maintenance of Electric Power Generation, Control, Transformation, Transmission and Distribution Lines and Equipment.

NFPA 70E addresses electrical safety requirements necessary to safeguard employees during activities such as the installation, operation, maintenance, and demolition of electric conductors, electric equipment, signalling and communications conductors and equipment, and raceways.

In regards to work practices and electrical system maintenance, NFPA 70E provides key information that is lacking in the National Electric Code(NEC). While the NEC is useful for those responsible for maintenance and engineering of electrical equipment, NFPA 70E is a voluntary standard purposely geared toward workers and employers to understand and implement safety precautions. While OSHA uses the General Duty Clause as the basis for citations, OSHA commonly cites information from NFPA 70E for support in order to enforce compliance regarding electrical safety.

Exclusions: A few industries are excluded from NFPA 70E: electric utility transmission, distribution and generation workers (who are covered byOSHA 1910.269), as well as the marine, railway rolling stock, and mining industry. Despite the exclusion, many of these industries protect workers with flame resistant (FR) clothing as a general practice.

System Classes: NFPA 70E breaks all electrical procedures into five classes and assigns minimum FR clothing layers and performance characteristics for each class based on the hazard present.

Historically there were five classes, but the 2015 edition eliminated category “0,” leaving four categories.

The classes were formally called Hazard Risk Categories (HRC), but the 2015 edition of the standard changed the terminology to PPE Category (CAT).

Other practical recommendations made within NFPA 70E address commonly asked questions:

Underlayers.  Meltable fibres such as acetate, nylon, polyester, polypropylene and spandex shall not be permitted in fabric underlayers (underwear) next to the skin.  “Informational Note No. 1: Arc-rated garments… generally provide a higher system arc rating than non melting, flammable fibre underlayers. “Informational Note No. 2: Arc-rated underwear or undergarments…generally provide a higher system arc rating than non melting, flammable fibre underwear or undergarments used as underlayers” (NFPA 70E-2012 p.33).

Layering. “Non melting, flammable fibre garments shall be permitted to be used as underlayers in conjunction with arc-rated garments in a layered system for added protection. If non melting, flammable fiber garments are used as underlayers, the system arc rating shall be sufficient to prevent break open of the innermost arc-rated layer at the expected arc exposure incident energy level to prevent ignition of flammable underlayers. Garments that are not ArcFlash shall not be permitted to be used to increase the arc rating of a garment or of a clothing system” (NFPA 70E p. 32).

Coverage.  “Clothing shall cover potentially exposed areas as completely as possible.  Shirt sleeves shall be fastened at the wrist and shirts and jackets shall be closed at the neck” (NFPA 70E-2012, p. 33).

Fit.  “Tight-fitting clothing shall be avoided.  Loose-fitting clothing provides additional thermal insulation because of air spaces.  Arc-rated apparel shall fit properly such that it does not interfere with the work task” (NFPA 70E-2012, p.33).

The most recent update to NFPA 70E is the 2015 edition. Changes of note related to flame resistant protective apparel include:

Elimination of Category 0: This category allowed non-FR but non-melting fabrics such as flammable cotton; it has been removed. Any situation with an arc flash hazard now requires Arc Flash FR clothing.

HRC Category renamed PPE Category: this change is semantic only; the math and logic did not change, but the name was changed to better reflect the purpose. Expect to see external labelling which used to say “HRC 2” move to“Cat 2.”

Addition of a yes/no chart to determine if an arc flash hazard exists — Table 130.7(C)(15)(A)(a) identifies when arc flash PPE is required.

Conductive articles are not permitted to cross the “restricted approach boundary”

Mining industry is now covered by 70E: the mining exemption in the scope was removed

Changes of note related to FR in the previous edition, published in 2012, included:

New terminology (Arc-Rated): Flame resistant (FR) has been changed to “arc-rated (AR)” in regard to personal protective equipment (PPE) throughout the standard.

Arc flash calculations in Annex D now align with the 2012 version of the NESC.

Hazard/risk category tables have been changed to include short-circuit current, fault clearing time, and potential arc flash boundary in each of the major equipment categories instead of in specific notes at the end of the table.

Head Protection Requirement:

Hazards Less than 12 cal/cm2: An arc-rated hood or balaclava with an arc-rated face shield must be used when the back of the head is exposed within the arc flash boundary when the hazard is between 1.2cal/cm2 and 12cal/cm2.

Hazards Greater than 12 cal/cm2: An Arc Flash hood alone must be used for hazards greater than 12 cal/cm2.

DC Voltages: Historically, NFPA 70E has focused primarily on AC(alternating current) voltages. The 2012 NFPA 70E includes more information about calculating and protecting against DC (direct current) voltages. Table130.4(C) (b) is used for calculating distances for system voltages.

Arc flash boundary: A specific boundary is now listed under a new column for each task. This addition aligns with the deletion of the “four foot.rule” in the 2009 Edition.

Building Clarification: Section 90.2(A) (4) has been revised to say, “Installations used by the electric utility, such as office buildings, warehouses, garages, machine shops and recreational buildings.” This deletion clarifies that NFPA 70E applies to these areas, even if they are part of a generating plant, substation or control center.

An Arc Flash Risk Assessment or Arc Flash Hazard Study / Analysis is a calculation performed by Professional Engineer to determine the thermal incident energy found at each location which determines the various arc flash boundaries and what personal protective equipment (PPE) must be used in approaching each boundary.

The short circuit study determines if all equipment is within OSHA standard 1910.303 (b)(4). An Arc Flash Study / Analysis should only be performed by experienced and qualified electrical engineers knowledgeable in power system engineering, IEEE 1584, NFPA 70E, short circuit, device coordination and arc flash studies.

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