What is the bigger problem?

[ptonsparky]

Now sure what the fix is yet.

 

[charlie b]

Obviously, the problem is that there is too much dirt here. The fix is to conduct a water washdown. :grin: What problems are you seeing?

 

[ptonsparky]

Notice the spark arc marks on the back panel at the nut & washer? Nothing mounted on the back panel has faulted to it so that leaves a lightning strike, or one hell of a fault at some time or another through the MCC.

I did not see this until examining the photos from yesterday. The corroded & overheated connections are obvious.

Equipment operators had commented about seeing sparks along the conduits and metal roof flashing at the last large motor failure.

Minor detail, but the GFP has been disabled and they have no grounded conductor brought in to the 2 Services. The RMC conduit is bonded in the POCO fenced enclosure but that is all. I suspect some years ago the service was changed from ungrounded to 480/277 by POCO and someone just figured conduit was good enough.

 

[charlie b]

Kidding aside, I was wondering why there are two conductors under each of the two lugs on the left, and three conductors under the lug on the right. Am I seeing this wrong, or am I missing something obvious?

 

[ptonsparky]

This is part of an autotransformer start for a 300 hp motor. (Reference another thread about overheated buss bars.)

 

[electricalperson]

first i would fix those connections. looks like the wrong size crimp and lug. they have obvious signs of a loose connection. without seeing the entire machine i cant really tell of any more code violations

 

[electricalperson]

and check the equipment grounding conductors because that little burn mark under the nut and washer might be a sign of a loose grounding conductor

 

[nakulak]

the conductors on the right are oxidized at the termination, and the ones on the left aren't. curious. is there a dc voltage gradient (cathodic deterioration) ?