Standards for electric arc protection

In most countries legislation exists, which states that wherever there may be risks to health and safety that can’t be controlled in other ways, the use of PPE is required. Whilst legislation offers guidance on electrical safety procedures, each working environment has its own hazards and as a result the PPE requirements may differ. To ensure electrical safety in the workplace at all times, a specification should be required for each working scenario. For instance, ordinary workwear will not suffice when doing electrical work, where there is a risk of being exposed to the effects of an electrical arc[HBC1] . Below you will find a short summary of legislative requirements of two major regions in which the electric arc standards are applied.

In the US, the key governmental regulation is the Occupational Safety and Health Act of 1970 which can be found in the US Code Title 29 (Labor) Chapter 15 (Occupational Safety and Health) and provides a general duty for employers and employees to comply with this act. In addition, the OSHA 29 CFR 1910.132 (PPE General Requirements) which sets a general duty of care requirements that when there is a health risk the employers should provide the appropriate training and PPE.

In Europe, PPE legislation is divided in two parts. One setting the obligations of the employers and employees and one covering the marketing of PPE in the EU.

EU PPE Users Directives (89/656) and respective national PPE legislations (for example the Personal Protective Equipment at Work Regulations 2002 in the UK) requires that wherever there may be risks to health and safety that can’t be controlled in other ways, PPE is required. The responsibility for supply of such equipment falls on the employer or the self-employed worker.

The PPE Regulations also require that PPE is:

• properly assessed before use to make sure it is fit for purpose
• maintained and stored properly
• provided with instructions on how to use it safely
• used correctly by employees

In addition, all PPE purchased must be ‘CE’ marked (see Fig. 1). The CE marking denotes that the PPE complies with the relevant essential health and safety requirements of the PPE legislation (whether the current Directive 89/686 until 20 April 2019 or Regulation 2016/425 after 21 April 2018). When looking specifically at Category II and III PPE, the CE marking also indicates that the PPE has been tested and certified by an independent notified body.

Applicable Standards For Protective Clothing Against Electric Arc Effect

There are two key sets of standards which can be used to ensure arc protective clothing is compliant with legal requirements: ASTM and IEC standards.

Note 1: The arc rating values – ATPV, EBT//EBT50 and the future ELIM determined by the open arc test method – allow a good differentiation between the arc thermal protective performance of different materials and clothing. This in turn allows the selection of arc protective clothing to be matched specifically to the level of protection determined and required by the risk assessment (IEEE1584).

Note 2: The box test methods only groups different materials and clothing into two arc thermal performance classes. There are many scenarios whereby class 2 protective clothing does not provide sufficient arc protection when working on or near to energized electrical equipment. Also, the commonly used risk assessment procedure (IEEE 1584) cannot be linked to the two arc thermal performance classes.

A common error sometimes made is to say that a Class 1 + Class 1 fabric or garment is a Class 2 fabric or garment. In many cases Class 1 + Class 1 ≠ Class 2. In addition, there is no Class 3 fabric or garment.

Note 3: Materials or clothing of the same arc protection class do not always offer the same level of arc thermal protection. Two different materials may be Arc Protection Class 2, but one may have a higher arc rating (ATPV or EBT50). The box test method does not allow full differentiation between the arc thermal protective performance of different materials or clothing.

Note 4: For most materials and clothing, the ATPV and EBT values determined by ASTM F1959/F1959M and the ATPV and EBT50 values determined by IEC 61482-1-1 can be considered as identical within the uncertainty inherent in the test method.

For some multi-layer materials or multi-garment assemblies, or when the number of wash cycles prior to testing have a major influence on arc rating values, there may be differences between values obtained by ASTM F1959/F1959M and IEC 61482-1-1.

The uncertainty inherent in the test method is on average about 10%. So, for the practical purpose of selecting protective clothing, all materials and garments with arc rating values within 10% of each other can be considered as providing roughly equivalent electric arc protection.