How is this even possible - open ground?

648 Views 5 Replies 5 Participants Last post by surferdude2, Apr 29, 2020

mkmona04

Discussion Starter · Apr 27, 2020

Discovered a ground wire in my circuit breaker box was not connected to the ground bar. So I plugged one of those little testers into one of the affected outlets and that tool showed there was NOT an open ground, as I expected it would.

So then I thought, maybe the unconnected ground in the circuit breaker box was touching the side of the grounded circuit breaker box somewhere. so as a test, I ensured the bare ground wire was touching bothering, did the same test, and the tool still showed there was no open ground. How is this possible? i would think that even though the neutral is connected to the neutral bar (which is bonded to the ground bar), would that yield this result? i don't think so cus i had other older circuits that have no ground wire and the little tool on those circuits showed an open ground?

I am certain I was looking at the proper circuitry and outlet and that my tool is not broken.

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AllanJ

· #2 · Apr 27, 2020 (Edited)

All equipment grounding conductors (ground wires in branch circuits and feeds) should be tied together wherever they come together. If parts of two different branch circuits go into the same box then their ground wires should be interconnected there . Then if at the panel the incoming ground wire for one of those branch circuits is is loose then that circuit would still show ground is unbroken.

Or somewhere in the suspect branch circuit ground and neutral touch where they should not.

Whereas when two feeding cables enter the same box, their neutrals must not be interconnected (combined) and only the hot conductors matching that neutral may follow that respective neutral onward. Thus it is possible to have two wire nutted bundles of (white) neutrals in a box, and duplex receptacles have a breakaway tab between the screws on the neutral side also.

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joed

· #3 · Apr 27, 2020

Two possibilities I can come up with.
1. There are two different circuits in the same box somewhere and the grounds are all tied together.
2. Someone couldn't figure out an open ground problem and tied the ground and neutral together somewhere on the circuit.

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surferdude2

· #4 · Apr 27, 2020 (Edited)

Or the circuit is serving some appliance that is also grounded by another means, such as water pipe or gas pipe. That doesn't fully explain why the true EGC was left off the terminal strip other than possible carelessness.

I suspect something else is going on here but it will require some exposing of outlets, etc. and I doubt it's worth the effort. I'd think a short between the ground and neutral would fool the tester but if so... so what... why would someone disconnect the true EGC if that was the case. If it was on a GFCI down stream fed circuit, a neutral to ground short would trip it... maybe that was happening and someone fixed it the easy way. I can't even make that work so until we get more info we won't know what's going on there.

And don't forget... you can't really 100% rely on those tester cubes. Maybe some appliance or other device had a ground fault and disconnecting the ground allowed it to be used. Don't laugh, I saw an example of that once where a customer told me he had to plug his room AC in a certain way or else it would trip the breaker. Turned out the compressor motor wiring was internally shorted to the laminates but at a point near where they terminated on the internal connection to the line.

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seharper

· #5 · Apr 29, 2020

Yeah, the descriptions on those testers leave a lot to be desired. Sperry issued a revised, more accurate label for mine:

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surferdude2

· #6 · Apr 29, 2020

Aaah.. the old black magic 8-ball that had all the answers...

https://magic-8ball.com/

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How is this even possible - open ground?

mkmona04

AllanJ

joed

surferdude2

seharper

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