According to the NFPA 70E, Arc Flash is a “dangerous condition associated with the release of energy caused by an electric arc.” It is measured in terms of arc flash incident energy E (AFIE), which is used to determine the level of Personal Protective Equipment (PPE).
An arc flash is the light and heat produced from an electric arc supplied with sufficient electrical energy to cause substantial damage, harm, fire, or injury. This can occur near high power electrical equipment such as transformers, service entrance switch gear or generators.
The first step to protection conduct an Arc Flash Hazard Analysis which defines the procedures and limits the damage of electrical arcs on personnel and, by measuring the released energy, defines the risk and determines the relevant level of the PPE required.
|HRC* 0 – 0 cal/cm2 ; 0 J/cm2:||Non-melting, flammable materials (i.e untreated cotton, rayon, wool, silk or blends of these materials) with a minimum fabric weight of 150g/m2|
|HRC* 1 – 4 cal/cm2 ; 16,74 J/cm2:||Arc Rated Flame Retardant shirt, Flame Retardant trousers or Flame Retardant coverall|
|HRC* 2 – 8 cal/cm2 ; 33,47 J/cm2:||Arc Rated Flame Retardant shirt, Flame Retardant trousers or Flame Retardant coverall|
|HRC* 3 – 25 cal/cm2 ; 104,6 J/cm2:||Arc Rated Flame Retardant shirt and FR trousers or FR coverall, and arc flash suit selected so that the system arc rating complies with the required minimum|
|HRC* 4 – 40 cal/cm2 ; 167,36 J/cm2:||Arc Rated Flame Retardant shirt and FR trousers or FR coverall, and arc flash suit selected so that the system arc rating complies with the required mini|
*HRC: Harzard/Risk Category
Selecting the correct level of Arc Protection Equipment (APE) is made easy from this table however there are a few questions to ask your APE supplier:
- Is the garment compliant with SANS 724:2010, NFPA 70E:2009 and SANS 984/IEEE Std 1584?
- Can they send you the relevant certifications?
- Does the garment meet your required HRC level?
- Has the garment been tested? (not the fabric – very important)
- If so, can they send you the test reports that include photos?
It’s important to note that where more than 40cal/cm2 APE is required it is not recommended unless all other means of reducing the risk of exposure has been investigated.
The Arc PPE you use really is your last line of defence, and following the above steps ensures that you are doing the best you possibly can to minimise injuries as a result of an arc flash incident.
Information supplied by: Dromex Personal Protective Equipment.
“Growing up in Namibia, I spent many of my holidays on my grandparents farm, which is in an arid area of the country. There was no electricity and every drop of water had to be pumped from a borehole. This didn’t worry my grandfather in the least.
Regardless of the season, he was up every morning before sunrise when the old cuckoo clock struck four, and was then in the kitchen making coffee. After this he headed out to attend the work of the day.
He didn’t press a “snooze” button. In fact, I doubt he ever set an alarm clock. His motto was:
“today, not tomorrow”.
He knew that when it was time to plough, that’s what had to be done, because the rains don’t have a snooze button. The same went for the cows. When they came into the kraal in the early morning, it was milking time. No hitting the snooze button.
The snooze button is an invention which encourages the poor habit of delaying unavoidable action.
Pressing the snooze button buys one a few extra minutes sleep, but doesn’t make a difference in the long run.
Instead of hitting the ground running, we fall prey to this folly of delayed action, which often results in things taking longer. Every time we choose “I-can-do-that-later”, we waste time picking up the thread and re-focusing.
In terms of safety, there are a number of examples. Two of these are OPPORTUNITY and RISK. Opportunity normally has a short time frame and if you press snooze, in most cases, you will lose out. The expression, “there will always be another opportunity”, is the language of losers.
The same goes for risk. Once it has been identified, it must be dealt with, because a risky situation cannot be put on hold. Actually, if swift action is not taken, an even bigger risk might be created by breeding complacency.”
Jurgen Tietz, diretor: eKhuluma and Disruptive Safety. Source: SHEQ Management, Issue 1 2018.