Electrical safety: Arc flash PPE

by | Mar 8, 2019 | Electrical Safety

According to Canadian accident statistics, a large proportion of accidents are caused by arc flash resulting in burns. Companies are therefore increasingly interested in safeguarding their electrical installations as well as in the prevention programs on electrical hazards that they provide to their employees. In this blog, it will be presented the different electrical risk assessment methods as well as the proper PPE to use for live work. Although not featured in this blog, the dangers related to electric shock are very common and often overlooked by workers.

 

There are two methods to assess the electrical hazards of an installation, either by performing an incident energy analysis that will inform on the energy levels for all equipment upstream of 125kVA transformers, or by using the risk/hazard category method to determine the arc flash PPE category using tables 6A and 6B from CSA Z462-18. The first method has been discussed at length in the blog on incident energy studies.

 

How to properly select PPE according to the incident energy level or the risk category?

 

In general, at the entrance of the plant, the energy level is very high, and it is thus recommended to use category 4 PPE (at least 40 cal/cm2). The incident energy is then reduced by passing through protections such as circuit breakers or fuse disconnects. Evidently, the lower the protection calibers, the more the incident energy level is reduced. It is thus possible to use PPE of a lower category to perform live work. On the other hand, at the output of the inductive loads, either generators or transformers, the incident energy level increases since energy is stored in the windings. It is thus very difficult to make the right PPE choice without an incident energy study. If an incident energy study has been performed, one can simply consult the arc flash and electrical shock hazard warning label affixed to the electrical panel to know the incident energy level at play and choose PPE accordingly before beginning the live work.

 

Description of each PPE category

 

There are four PPE categories for arc flash hazards. The higher the category, the higher the energy level. The prescribed PPE will have to be designed to withstand increasing energy levels which each category. Here are the requirements of each category as stated in the standard CSA Z462-18:

 

Category 1 :

  • Clothing of Minimum Arc Rating of 4 cal/cm2 (16,75 J/cm2)
    • Arc Rated long-sleeve shirt and pants, or Arc Rated coverall
    • Arc Rated face shield, or Arc Rated flash suit hood
    • Arc Rated jacket, parka, rainwear, or hard hat liner

Category 2 :

  • Clothing of Minimum Arc Rating of 8 cal/cm2 (33,5 J/cm2)
    • Arc Rated long-sleeve shirt and pants, or Arc Rated coverall
    • Arc Rated flash suit hood, or Arc Rated face shield and Arc Rated balaclava
    • Arc Rated jacket, parka, rainwear, or hard hat liner.

Category 3 :

  • Arc Rated clothing, selected for the system’s arc rating to be at least 25 cal/cm2 (104.7 J/cm2)
    • Arc Rated long-sleeve shirt,
    • Arc Rated pants,
    • Arc Rated coverall,
    • Arc Rated flash suit jacket,
    • Arc Rated flash suit pants
    • Arc Rated flash suit hood
    • Arc Rated gloves
    • Arc Rated jacket, parka, rainwear, or hard hat liner.

Category 4 :

  • Arc Rated clothing, selected for the system’s arc rating to be at least 40 cal/cm2 (167.5 J/cm2)
    • Arc Rated long-sleeve shirt,
    • Arc Rated pants,
    • Arc Rated coverall,
    • Arc Rated flash suit jacket,
    • Arc Rated flash suit pants
    • Arc Rated flash suit hood
    • Arc Rated gloves
    • Arc Rated jacket, parka, rainwear, or hard hat liner.

 

Protective Equipment for all categories

  • Hard hat
  • Safety glasses or safety goggles (selection required)
  • Hearing protection (with plugs)
  • Heavy-duty leather gloves
  • Leather footwear

 

It is important to specify clothing with reflective stripes when purchasing PPE. The following table shows different images of PPE, as well as relevant information to verify.

 

Table 1 : Relevant information regarding PPE.

 

Once the purchase of PPE has been completed for the entire plant, it is important to store and maintain them properly to avoid them being in contact with contaminants such as oil or any kind of petroleum-based product that may affect their effectiveness. Also, they should be cleaned regularly if the work is done in environments with contaminants. Also, the recommendations of each equipment must be followed before they can be use and it is important to replace them before the expiry date.

 

This blog helped to learn more about the PPE to use to protect workers from arc flash. However, to fully cover electrical safety, the dangers of electric shock that are often overlooked by workers should be taken into account. Indeed, regularly, workers do not know when to use PPE and what to do in case of shock. For more information, visit the blog on personal protective measures against shocks.

 

Contact our experts for more information!

 

References

  • IEEE 1584-2002 – IEEE Guide for Performing Arc Flash Hazard Calculations
  • CSA Z462-2018 – Electrical Workplace Safety
  • CSA Z463-13 Guideline on maintenance of electrical systems
  • NFPA 70E-18 Standard for electrical safety in the workplace
  • ANSI Z535 – Safety Alerting Standards

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Intervention Prévention Inc.

Intervention Prévention concentrates its operations in the field of work safety, offering specialized services following Standards CSA Z462 – Workplace Electrical Safety, CSA Z460 – Control of Hazardous Energy: Lock-out and Other Methods, and CSA Z432 – Safeguarding of Machinery.

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