Mitigation is defined as, “to make milder, less evere or less violent.” When applied to elec- trical workplace safety, arc flash mitigation
involves taking steps to minimize the level of hazard
and/or risk associated with an arc flash event. ANSI
Z10-2012, Occupational Health and Safety Management
Systems, released a hierarchy of arc flash mitigation controls, as shown in Figure 1.
Personal Protective Equipment (PPE) is often mistakenly viewed as the solution to arc flash hazards. In reality, properly selected PPE does not guarantee freedom
from injury. NFPA 70E only makes the claim that injuries sustained during an arc flash event would be reduced
and survivable due to mitigating effects of arc-rated PPE.
The most effective arc flash safety programs look
to incorporate “safety by design,” where effective
mitigating techniques, including engineering controls, are
used to reduce the risk to the worker. The engineering
controls covered in this article will reduce risk by either:
1)Reducing the available arc flash energy level, or
2)Reducing the exposure of the worker, so that he/she is
not subject to harm.
Solution Group 1: Reduce Arc Flash
The Role Of The Circuit Breaker Or Fuse In
Lowering Arc Flash Energy Levels: Why is a circuit
breaker or fuse always considered in arc flash analysis?
Because arcing time is the key determining factor for
arc flash energy. Per the equations in IEEE 1584-2002,
arc flash incident energy varies linearly with time. If the
duration of the arcing fault doubles, the available energy
Arc Flash Hazards
By Antony Parsons