Arc flash hazard raises many questions

Electrical Apparatus, Apr 2007 by Nailen, Richard L

By January 2006, a Steering Committee had been formed, which created a working group called the Research and Testing Planning Committee, or RTPC. In turn, the 20member RTPC set up seven Test Groups, each to "identify and recommend testing protocols" concerning such specific conditions as thermal effects, "hazards other than thermal and electromagnetic," and the "impact of enclosures."

Expected to require several years for completion, the project now envisions thousands of separate test procedures. The original testing supporting issuance of IEEE 1584 has been strongly challenged by some engineers, and the effects of d-c arcs (as yet entirely untested) are widely debated. From an original budget estimate of $3 million, the estimated testing cost had risen by the end of 2006 to nearly $7 million, about one-third of it committed.

Other questions are being asked about the calculation procedures outlined in IEEE 1584. We can't go into those details here. But engineers have acknowledged that only more testing, under a variety of conditions, can provide answers, and that applying the methods in the same way to the whole range of system voltages can give unrealistic results.

Whether the NFPA/ IEEE collaboration will settle such questions remains to be seen.

By Richard L. Nailen, P.E.,

EA Engineering Editor