I'm working for a school system with 20+ buildings of various ages from 100 to 0 years. Many of the fuse and panel boards are not marked or incorrectly marked. We've been having trouble adding outlets and lights to circuits with shared neutrals in 120/240, 120/208, and 277/480 configurations. I'm looking for a method to determine the origin of a circuit and the other hot wires associated with the shared neutral. Are there any trick ways.

My current idea is to make a flashing load of several amps, connect it to the circut. Then go back to the expected panel board and look for wires that amprobe at the flashing rate. This should id the hot and neutral for the target circuit. Then I grub in the panel board for other hots associated with neutral. AssUme'ing no one's tapped a random neutral wire in a junction, I've found the hots and neutral.

I'd like much easier way... if it exists.

Thanks,

Jim Williams

JFW