Hi
I am new to this forum and to the Arc flash and live work regulations. We are reviewing our company's procedures for this and I have found this forum very helpful.

I would like to find out what the ARC flash PPE recommendations would be for live testing on either the field isolator or motor terminals of a motor in the field. Our MCC's are mostly 525V AC and have fault levels below 15kA, they are equipped with Isolators, fuses, contactors and overload units. I would think that it would not be more that HRC 1 or perhaps even 0 seeing that the fuses should bring the fault levels down significantly along with the length of cable from the MCC to the motor (probably between 20 and 50m). We would not want to be doing the ARC calculations for each and every motor if it is not needed.

Your input would be greatly appreciated.

The arc fault energy is likely low but unless calculated not known.

This is similar to the dilemma of labeling Horsepower Rated disconnects and the amount of work needed to do all those calculations.

Welcome to the Arc Flash Forum! Adding to Jimmy's comment, it is really hard to tell since the incident energy is a function of BOTH the fault current AND the device clearing time. The clearing time is often the big question but if your device trips in a few cycles, the energy is likely lower (just a thought, not a formal opinion or conclusion)

As a first step in mitigating the risks of arc flash, you should consider why you need to perform this task live, rather than isolate, connect test equipment and de-isolate.