Practicing at work

My current day job requires me to remove deadfronts annually and do an “inspection”. That means to my current employer “make sure nothing is or has been on fire”

Applying my new training, I am now going beyond to help me when I transition to inspections for a living.

Pictures are of a service disconnect rated at 400 amps. Service is overhead to the end of the building, then approximately 60’ underground through RSC to this point. Second picture is the listing tag for the lugs.

Phases A and B are 500 MCM feeders, with a #2 in the same lug to feed another 100A main in a subpanel. Phase C has a #3 feeder and a #2 for the third phase in the subpanel.

Based on what I know so far, I would write up these defects:

  1. “SEC for Phase C is undersized” - I can’t see any circumstances where a #3 can carry 500 amps - especially underground in conduit with 2 other ungrounded conductors.

  2. “Improper connection of two conductors to breaker lugs” - see listing label. I don’t see where the combination of a 500 MCM and a #2 is allowed, nor a #2 and a #3. One of the conductors is doubled over on itself to provide enough for the setscrew to grip onto.

Please correct me where needed.

Listing for lugs.jpg

You’re correct on the two conductors under one lug being outside of the range of the terminal. Could the C phase be grounded?

It was common to do that when it was a 120/240V 3Ø supply, not right but it was done often, the “logic” was that the load on the stinger leg was lower then the other two. If it was a fusible switch & a smaller fuse was used on that leg, it would be fine, what is the voltage? 208Y/120V or 120/240V? Color code sez 208, but it’s foolish to rely on the colors, verifying by testing is the only way. There are other issues too.

I don’t believe so. This shot is the panel that those #2’s go to - a main breaker for a panel upstairs. It has the grounding conductors you would expect.

Would a three phase delta explain the smaller conductor for phase C? Phases A & C provide 120v for lighting and convenience outlets, while the 208 voltage of phase C wouldn’t be of any use in a light retail situation - There aren’t any 3 phase loads in the building. There used to be a three phase AC condensor, but some Einstein installed a single phase replacement, so even that is gone.