We have a computer room with a couple dozen racks. Each racks has three phase power running to it hardwired from our UPS. Each rack has a PDU that brings out the three pairs (phase 1-2 -> 208V, phase 2-3 -> 208V and phase 3-1 -> 208V). The neutral is not pulled from the UPS to the racks. All loads are single phase.
So far so good. recently we started to see one of the phases with a higher load on it than the others. Our attempts to balance the loads only skewed it more which lead us to find out that the electrician wired the phases inconsistently to the racks. In some racks phase 1-2 on the UPS side is actually on the 2-3 outlet group, etc. Figuring this out is extremely time consuming and dangerous to our data integrity (it means rooting around in the back of the racks, adding or removing loads and monitoring the meters on the UPS in a live environment.
Since the computer room is in production use, we do not have the luxury of switching everything off and tracing the wires.
Is there a device / method that would let us trace the phases from the panel to the rack without having to de-energize everything?