From the EMailbag:

Quote
I have had a wire pinched within a 90 degree 3/8 MC cable connector short out. This caused a short circuit which bypassed the 480/277volt 20 Amp individual branch circuit breaker supplying the flourescent 277 volt fixture, then bypassed the 200 amp fused bus disconnect feeding the 42 circuit panelboard (MLO) on the floor, and finally openned the 1600 amp GFCI pringle switch which feeds the bus riser for that part of the building. The same type occurance made a 2000 amp GFCI pringle switch open on another part of the building last month. Why won't the branch circuit breaker on the floor trip. I suspect the pringle switches are set too sensitive.

Thanks RH
I've invited RH to comment if necessary

Bill