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No power in 1 room in the house

P

paulney

Diamond Member
Hey, ATOT, I need your wisdom. I'm not an electrician, so please help me out here!

I had contractors remodeling a master bathroom. As part of the work, they replaced an old plug with GFCI plug, removed the wall light and left the wires hanging for now - they are coming back in 2 weeks to continue work and put a lamp back).

Contractors finished bathroom work a few weeks ago and left until the vanity would arrive. All of a sudden yesterday I lost power in the room and in the bathroom.

The whole house has only 1 line dedicated to all lights and sockets. So, if I trip the breaker, everything shuts off. I reset it, and the whole house functions fine except the master bedroom.

I started poking around the sockets. Here's what I found (consult the diagram below):

GFCI: power coming in normally, 120 V betwen hot and neutral and hot and ground. No power anywhere in the GFCI itself. I can't reset it - it won't stay (not even lock at all).

Exposed lamp: power neutral and ground; no power between hot and neutral; power between hot and ground.

All regular sockets in the room: power neutral and ground; power between hot and ground; no power between hot and neutral.

I do not have the wiring blueprints for the house, but I suspect the GFCI socket is at fault?

Update: I just replaced the GFCI. The new one resets and tests beautifully, so at least I have 1 functioning outlet. The rest of the sockets, however, including all the switches in the room still experience the same problem: All regular sockets in the room: power neutral and ground; power between hot and ground; no power between hot and neutral.

I guess something happened somewhere, which killed the GFCI and now I am seeing the circuit problem?

Update:So the problem seems to be in the exposed lamp fixture. I shorted the neutral with the ground - and every single socket and switch came back to life.

ElectricalDiagram.png
 
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Or wired backwards. There should be a LINE terminal set and LOAD set. Ensure the feeder (wires with power) go to LINE and the rest is on LOAD. In fact if the rest of that load does not need to be GFCI protected you can put it on LINE (pigtail it, don't double the wires).
 
Come to think of it, easy way to rule out GFCI, just bypass it, then check the first socket for power. If there's power at the GFCI box, but not at the socket, then the problem is with the wire. Perhaps it's going to a hidden junction box you don't know about, or a wire got cut somewhere. Test between the hot and the ground for kicks, maybe the neutral got nicked. Also test between a known good hot (may need to plug an extension cord and bring it to the socket) and the neutral and ground. By doing this you can isolate if it's a single wire that's affected. Not that it will do much good to isolate as you still need to find it.
 
The contractors have used a common feature of GFCI's. It is wired as the FIRST device in the circuit supplying these two rooms, and the remaining devices are powered from output terminals on the GFCI. This means the entire circuit is protected BOTH by the panel breaker (for overcurrent) AND for unbalanced current (which is taken to indicate abnormal current leakage, and hence a dangerous situation). Since the GFCI is tripped and cannot be reset, no device after it gets power.

The cause could be either of:
(a) as suggested, the GFCI is faulty; or,
(b) the GFCI is right, and there is something plugged in somewhere causing current leakage out of the proper circuit - could even be faulty wiring, rather than a faulty appliance plugged in. To test this, take these steps:

1. Unplug everything on the circuit in both rooms. See if you can reset the GFCI with no load. If that works, go around one at a time and turn on lights and / or plug in things until the GFCI trips again. You just found the culprit.
2. If the GFCI still cannot be reset with no load, it may be faulty. IF you feel competent to do this, you can do another test for faults in the circuit AFTER the GFCI. You turn off the breaker for the circuit at the panel, then remove the GFCI unit from the box it is mounted in. Leave its Hot and Neutral supply wires connected, but disconnect the wires from its output to the remaining circuit. Ensure the GFCI unit is not touching anything (just supported by its wiring) and turn the panel breaker back on. See if you can reset the GFCI now. If it still won't reset, it may be faulty.

I had a mysterious GFCI problem recently - it would reset OK, but trip again as soon as any load was put on the circuit. It turned out to be a poor (dirty and loose) connection between two wires delivering power to it. Apparently this got interpreted as an unbalanced voltage or current flow and tripped it when loaded.
 
Contractors get nervous about homeowners fiddling around with work that is still in process or under warranty. It's not a huge deal but if you are happy with the relationship between you and the contractor I would suggest giving him a call and letting him take care of it if at all possible.

If you happen to make a mistake or have similar problems in the future it can lead to a blame game that sours the relationship.
 
Update: I just replaced the GFCI. The new one resets and tests beautifully, so at least I have 1 functioning outlet. The rest of the sockets, however, including all the switches in the room still experience the same problem: power from neutral to ground, but no power between hot and neutral or hot and ground.

I guess something happened somewhere, which killed the GFCI and now I am seeing the circuit problem?
 
GROUND AND NEUTRAL SHOULD HAVE ZERO VOLTS BETWEEN THEM.

Someone fucked something up. Ground is, more or less, a redundant neutral for safety reasons.


edit: wait a second. What you posted isn't even possible with power from neutral to ground, but no power between hot and neutral, or between hot and ground.
 
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Woah I missed that. Yeah probably got reverse polarity going on somewhere.

But since you got a contractor think I'd just let him know and let him worry about it.
 
Here's the big question: how the hell do people end up with reverse polarity?! The wires are fricken color coded! "Hey Bob, you know, I'm kind of bored with all this wiring. I think that this time, I'm going to connect the black to the white, and the other white to the black." Then again, wires haven't always been color coded... I do have some wiring in my house that's about 50-60 years old that isn't color coded. Eventually, every last inch of that crap will be torn out of here and replaced.
 
DrPizza said:
Here's the big question: how the hell do people end up with reverse polarity?! The wires are fricken color coded! "Hey Bob, you know, I'm kind of bored with all this wiring. I think that this time, I'm going to connect the black to the white, and the other white to the black." Then again, wires haven't always been color coded... I do have some wiring in my house that's about 50-60 years old that isn't color coded. Eventually, every last inch of that crap will be torn out of here and replaced.
Click to expand...

Dunno man. I had a wiring issue. I was putting black to black and purple to purple. Turns out it was supposed to be black/purple black/purple. Figure that shit out.
 
DrPizza said:
GROUND AND NEUTRAL SHOULD HAVE ZERO VOLTS BETWEEN THEM.

Someone fucked something up. Ground is, more or less, a redundant neutral for safety reasons.


edit: wait a second. What you posted isn't even possible with power from neutral to ground, but no power between hot and neutral, or between hot and ground.
Click to expand...

Ok, I goofed up and measured poorly the first time: I do have power neutral-ground and hot-ground, but no power hot-neutral. On all the sockets except the GFCI I replaced.
 
paulney said:
Exposed lamp: power neutral and ground; no power between hot and neutral or hot and ground.

All regular sockets in the room: power neutral and ground; no power between hot and neutral or hot and ground.
Click to expand...

The circuit has hot and neutral switched downline of the GFCI. You can't reset the GFCI because it immediately sees a short to ground though the neutral bus bar in the box and trips.

I don't understand how your lamp could work, because the circuit breaker should immediately trip because there is voltage on the neutral line. My guess is that your house isn't wired using the standard color coses and the electrician FUBAR'd it.
 
So the problem seems to be in the exposed lamp fixture. I shorted the neutral with the ground - and every single socket and switch came back to life.

Of course, this is a temporary solution, and I can't leave it like that. The problem is that I have to leave for 3 days tomorrow, and mother in law stays home with 2 kids. Can I leave the neutral shorted with the ground for now? They will be using the lights in the bedroom, but nothing more than that.

The exposed wire is also high off the ground, so no one but me can reach it.
 
Is there a second neutral in the box for the lamp fixture? If so, then there is your open neutral. When they get connected with installation of the lamp everything will be fine. If not, then you have an open neutral upstream from that fixture. By connecting the neutral with the ground and restoring power means that you are now using the ground as the neutral in this circuit and this might very well be a long standing problem that wasn't evident when everything was connected previously.
 
From your description, this sounds like a fairly typical open-neutral fault. Somewhere, the neutral wire has become disconnected.

This is a very dangerous fault and should be repaired as a matter of urgency. Shorting neutral and earth will 'work around' the problem by providing an alternative path for current flow. Often, earth and neutral are joined at the service entrance (or sometimes, joined at the power transformer).

However, earth conductors are often undersized, as they are only designed to handle fault conditions, not regular use. They are also almost never overcurrent protected (depending on the overcurrent protection in the phase conductor). Additionally, by providing your current path in a very flimsy light socket, you are directing all current in that circuit through the light socket, which is likely to be severely overloaded.

Finally, shorting earth to neutral defeats GFCI protection, and may cause GFCIs to fail to stay on (instant trip).
 
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