Can someone explain, if so why to run an EGC for each circuit. This is a room with any special equipment in Lake linder airport in lakeland, There is 120/208v, 3 ph, 4 wire panelboard which every circuit has his own EGC, let's say one conduit with 2 circuits and 2 egc, another conduit with 3 circuits and 3 egc inside, and so on. they're not isolated ground wire. I've never seen that and when I asked about, the electrician said spec mandatory.
Is there some specific rule or standard beyond the nec that establish regulations for this type of installation?
Is there some specific rule or standard beyond the nec that establish regulations for this type of installation?