Arc Flash Basics

What is an Arc Flash?

Is the light and heat produced from an electrical arc supplied with sufficient electrical energy to cause substantial damage, harm, fire, or injury.

What causes an Arc Flash?

An insulation breakdown, it can be through;

  • insulation deterioration
  • inadvertent shorting of phase conductors, phase to neutral conductors or phase to earth conductors
What can be the result of sufficient electrical energy?

Enough electrical energy to cause;

  • 2nd degree burns or greater
  • damage that results in equipment replacement
  • equipment fires
What governs the release of sufficient electrical energy?
  • Having sufficient generating capacity (kW, MW etc.)
  • The impedance to the source (conductor size and length, transformer size and impedance)
  • The fault current available (kA)
  • The time the arc takes to extinguish (The time the protection system takes to operate)
Insufficient electrical energy?

In most domestic situations, there is normally insufficient electrical energy to cause a significant arc flash event.

In the event of an arc flash, normally the electrical installation’s impedance to the source is high enough that it limits the level of fault current.

Sufficient electrical energy?

In large Commercial/Industrial/Mining installations, there is often sufficient electrical energy. Especially electrical installations and equipment that is close to major switchboards or large transformers.

In the event of an arc flash, the electrical installation’s impedance to the source is low enough to allow high levels of fault current to flow.

Do you understand the risks you are taking if you work in an environment where there is sufficient electrical energy for an arc flash event?

If you understand the arc flash risks, do you mitigate the risks or ignore them, if you ignore them then quite often there is an attitude problem or a peer pressure problem. Is your life worth the risk?

If you don’t understand the arc flash risks and you are working in a Commercial / Industrial / Mining environment, why are you doing the work. Further training is required so you can understand arc flash risks, mitigate the risks and know when it is not safe to proceed with the work.

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