I'd like to start by saying I have no problem hiring a pro if this isn't a DIY fix, but I would like to understand the problem before I do. There is a [B]tl;dr[/B] at the bottom if you don't have time to read the whole thing. I have two circuits with wiring issues and I think the problems are related. Here is what I have discovered so far: When an outlet tester is used on a receptacle on Circuit #1, both yellow lights come on (correct). When an outlet tester is used on a receptacle on Circuit #2, both yellow lights come on, and the red one comes on 1/2 way. Google pointed me to a reference describing this situation as "the wiring is FUBAR". When an outlet tester is used on a different receptacle on #1, all three lights come on (FUBAR). If I plug a UPS into the other outlet on this receptacle, the red light on the tester goes out (correct) and the UPS's "building wiring fault" light comes on. This receptacle has a ground wire joining it to a ground wire from a light on #2. #2 has no ground to the panel. But, some of it appears to have been upgraded and now has a ground wire. It's unfortunately not possible to run a ground wire to the panel. #1 and #2 are on different legs and do not have a shared neutral. [B]tl;dr: Is it a problem to share ground, particularly if the two hots are on different legs?[/B] Thank you in advance to anyone who would care to tell me their opinion.

Got a problem with a GFCI breaker that suddenly started tripping. I tried to isolate the problem and figured out that it will trip whenever a regular circuit breaker on a main panel that is related to plugs/sockets. Now, what confuses me is that I could not find a faulty socket. All our sockets have a safety shutter. Went to methodically switch off all of them, but could not find the culprit that causes the tripping. Does that mean that the issue is with the regular circuit breaker? Any help would be greatly appreciated.