Do you consider operation of a circuit breaker or switch the first time after installation or completion of maintenance in the equipment as a low arc flash risk - i.e. low likelihood of occurrence? Assume the 6 conditions of “normal� have been met – Properly installed, properly maintained, etc.

Do you consider operating a CB for the first time after installation or maintenance a low arc flash risk?
Yes
No
Not sure

I voted Not Sure as this is a wide class -CB. Are we referring to MCCB, ICCB or LVPCB? What about vintage breakers like from the 1960' that have just been PM'd and this is the first operation of it back in the cubicle? What about a breaker in a MCC bucket where the bucket was removed, PM'd and re-installed? Are stabs lined up properly?

I think each case has to be examined from a risk perspective on the first operation.

Seems like IEEE 493 would indicate 1st time operation as low risk. 493 was updated by the Dept. of the Army in 2006 (TM-5698-5) and the MTBF #'s were even lower in terms of failure rates for circuit breakers. I would concede though it would depend on when the breaker was manufactured.

Mike