Important Arc Flash PPE Safety Information
Arc Hazard Assessment Software
The Heat Flux Calculator is a free software program created by Alan Privette and is made available to the general public for the purpose of calculating heat flux received by a surface at a known distance distance from an electric arc.
Several layers of legislation exist within the UK and Europe that govern the need to assess workplace risks (including live electrical work), mitigate these risks and provide Personal Protective Equipment (PPE) where a risk still remains.
This legislation is available for free download along with guides on using and implementing their requirements from the Health and Safety Executive in the UK from www.hse.gov.uk and also by corresponding bodies across Europe.
The key pieces of legislation affecting the electrical industry, the risk of Arc Flash and using electrical PPE are:
- Health And Safety At Work Act 1974 (HASAWA)
This is the “umbrella” legislation that defines how workplace health, safety and welfare is controlled.
- Management of Health and Safety at Work Regulations 1999
A more detailed document that covers the principles needed to ensure workplace health and safety. This covers the need to carry out risk assessments.
- Personal Protective Equipment at Work Regulations 2002
This implements the requirements of the European PPE directive.
- Provision and Use of Work Equipment Regulations 1998 (PUWER)
Covering the provision of safe working equipment and the training in its operation.
- Electricity at Work Regulations 1989
General electrical regulations that cover working on or around electrical equipment including live systems.
Arc Flash PPE - Personal Protective Equipment (PPE):
In Europe any PPE sold must meet the requirements of the PPE directive 89/686/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 "Arc Rating", commonly given as an Arc Thermal Performance Value (ATPV) or Breakopen 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 (8000 Amps). 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 EN 61482-1-1 tests. IEC61482-2 is a technical specification that defines how to build Arc Flash garments. It does not cover handwear, 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.
Specifying Arc Flash Protective Equipment:
- Always complete an Arc Flash risk assessment on all equipment that will be operated or worked on live. This meets your regulatory requirements as discussed above and provides the key information such as incident energy used to drive risk reduction and PPE selection if required. International best practice for carrying out an assessment is given in IEEE1584-2002 but other regional methods exist such as those given in NFPA70E in the USA and BGI5188 in Germany.
- Mitigate arc risks. Reduce instances of live working, distance workers from sources of arcs, implement arc reduction and suppression technologies or reconfigure electrical networks to reduce the intensity of potential arcs.
- Any residual risks may then be met with PPE if needed. PPE should be selected based on the following:
- Arc rating of garment must be greater than the Potential Incident energy resulting from an electric arc.
- Wearability of clothing must ensure that workers can and will use PPE under all circumstances encountered.
- Durability to ensure protection offered lasts for the life of the garment and will need to wash out.
- Suitability of the style and cut of the clothing to meet the needs of the workers and the tasks they carry out.
NFPA 70E 2015 Edition
Table 130.7 (C)(16)
Hazard Risk Categories and Arc Resistant (AR) PPE
|Hazardous Risk Category||Clothing Description||Minimum Arc Rating of PPE cal/cm2|
|1||AR long sleeve shirt/jacket & AR Trousers or AR coverall, Hard hat, Safety glasses/goggles, Hearing Protection. Leather gloves & footwear||4|
|2||AR long sleeve shirt/jacket & AR Trousers or AR coverall, AR hood/faceshield, Hard hat, Safety glasses/goggles, Hearing Protection, Leather gloves & footwear||8|
|3||AR long sleeve shirt/jacket & AR Trousers or AR coverall, AR hood, Hard hat, Safety glasses/goggles, Hearing Protection, AR gloves, Leather footwear||25|
|4||AR long sleeve shirt/jacket & AR Trousers or AR coverall, AR hood, Hard hat, Safety glasses/goggles, Hearing Protection, AR gloves, Leather footwear||40|
Factors Affecting the Extent & Seriousness of Worker Injury when Exposed to Arc Flash
- Electric arc intensity
- Fault current
- System voltage
- Electrode gap
- Number of phases involved
- Open arc configuration or enclosure
- Electric arc duration
- Distance of the worker from the electric arc
- Type and fit of clothing worn
- Age and health factors
Clydesdale FR Fabrics
Clydesdale uses Westex Indura Ultra Soft® exclusively. Indura Ultra Soft® blend of 88% cotton and 12% high tenacity nylon substantially increase the fabric’s abrasion resistance helping the garment last over 50% longer than 100% cotton garments. Plus the softer feel further enhances the breathable ‘all-season comfort of cotton. The treatment process for Indura flame resistant fabrics forms a long chain flame retardant polymer impregnated into the core of each cotton fibre which gives PERMANENT & GUARANTEED FLAME RESISTANCE FOR THE LIFE OF THE GARMENT. An excellent value equation.
Effects of Electrical Shock
Even relatively low voltages can be fatal. For example, electrical shocks produced from common 50 Hz ac power passing from hand to foot for a duration of one second can have the following effects:
|1-3 Milliamps||Tingling Sensation|
|3+ Milliamps||Shock (pain)|
|10+ Milliamps||Muscular Contractions (can’t let go)|
|30+ Milliamps||Respiratory Paralysis (may be fatal)|
|60+ Milliamps||Ventricular Fibrillation (usually fatal)|
|4+ Amps||Heart Paralysis (fatal)|
|5+ Amps||Tissue Burning (fatal, vital organs destroyed)|