Messed up voltage/circuits/receptacles

[Keith Nordyke]

I have a detached shop fed by a subpanel. I didn't build this mess and am trying to live with it until we move in the spring. A 110 v circuit containing three receptacles has worked until yesterday. None of the three outlets now work. I pulled the receptacles on all three and:
1. One outlet tests "open neutral" (I didn't check the voltage on this one)
2. The center or middle outlet tests "open ground" and measures 62 volts.
3. The last outlet also measures 62 volts and tests as "open neutral."

This building was built about 40 years ago and appears to have a forerunner of romex 12/2. The wiring disappears back into the wall and can't really be traced as the builder built in a heavy bench across that wall. The boxes don't have the green ground screw so the grounds are just wirenutted together in the box. My inclination for tonight is to replace ALL of the receptacles and see if that cures the problem. IF I can determine which way the circuit runs, I am thinking about putting a GFI in the first box. Any sparkies out there that can diagnose this and lead me down the right path? Thanks.

[Jason Roehl]

Sounds like the first of the three outlets on the circuit has a loose connection of some sort. I would pull all three and add "pigtails".

What are pigtails? Well, rather than running the circuit wires directly to the outlet, they get nutted together in the box, with an extra short length of wire also in the wire nut--this is the wire that goes onto the outlet terminals.

When using wire nuts, you should always test each wire in the nut to make sure it is secure. Some people twist the wires together before adding the nut, but I don't find it's necessary with a good wire nut and technique.

[Chris Padilla]

When using wire nuts, you should always test each wire in the nut to make sure it is secure. Some people twist the wires together before adding the nut, but I don't find it's necessary with a good wire nut and technique.

Here in EQ country, it is the code to first twist the wires together before also twisting the nut on...EQs can shake those sucker apart otherwise!


;)

[Mark Bosse]

If you can, get a licensed professional. Failing that,

Go to the panel that seems to contain the breaker for this circuit. Inspect carefully two things: whether there is a ground wire running into the panel and out to the branch circuit and; get tough on the neutral bus. Pull all the neutrals out, clean and reattach to the specified torque.

Once you know whether there is a grounding conductor running into the panel and are very sure the neutral is solid, then post again.

In my limited experience, this situation happens when the neutral is messed up in the panel. I have seen that happen due to poor neutral connection to the bus and when people fake a ground by bonding to the neutral at the panel (when the panel was wired without a grounding conductor).

This could be even worse if the panel is a 3 wire 220 v panel with no real neutral. If someone is faking a neutral by backfeeding the ground on the feeder, you need help. For you skeptics, this situation happens when a properly built 3 wire 110 box (panel or otherwise) is converted by a homeowner into a 220 box. It can easily be "upstream" from the subject box. Check every box between the subject panel and the meter base.

If anything I am describing is true, GFI or AFD will fail.

I wish you luck.

[Keith Nordyke]

I changed out all receptacles and as was guessed, it did NOT cure the problem. They needed to be changed anyway as they were crumbling.

The panel was opened and:
1. Is is 240 with 2 hots and a neutral
2. The "bad circuit" (Hereinafter "Circuit ONE") does have a neutral AND a ground. BOTH are wired into the neutral bus.
3. The neutral bus also has a large copper ground wire leading to a ground rod.
4. There isn't a separate ground bar in the panel
5. ALL of the circuits are wired the same (neutral and ground into neutral bus).
6. Only Circuit ONE is testing open neutral

I can't shut down the panel tonight to clean and tighten as there is no light out there. I'll do that tomorrow. My thinking at this juncture is A) problem in the connection in the panel or B) critter chewed the neutral somewhere in the wall.
Based on the above, any thoughts? Thanks

[Mark Bosse]

When you check the neutral bus, try poping the hot wire off its breaker (with main off of course). Then, use your tester directly on the breaker, neutral bus and ground (also on the neutral bus).

If the tester still shows a floating neutral, start heading upstream. Check again at the point where the feeder for the problem panel takes off from the upstream panel, etc.

Crazy idea - but, have you checked the tester on a circuit which operates normally?

[Mark Bosse]

Sorry to have delayed this part of my response. I needed to check with my electrician.

If the ground and the neutral on the feed to your problem panel are both bonded to a single neutral bus in the panel and you have a ground rod in this panel, then the subject panel must either:

(a) be your main panel (the one between your meter base and every single device serviced by that base), or

(b) you have a ground loop.

Basically, there should be four "busses" in your panel; ground, neutral, and two hots. If not, then whoever built the panel did not know that they needed to buy the optional ground bus connector. It is never correct to have more than one place where the ground and neutral are bonded together.

Given what you have posted, you really should get a licensed professional to look at this. This sort of panel setup was described to me as "farmer wiring" that " burns places down."