Circuitry Mystery
November 11, 2012 6:23 AM   Subscribe

Electrical Filter: Help me figure out how an electrical circuit seemingly got rewired overnight.

Went to sleep last night and my electricity was fine. Woke up this morning and it was partially out, like a fuse was blown. Overhead lights worked, but no wall outlets in the kitchen or living room. I live in an apartment with no circuit breakers or fuse box to check, so I put in a maintenance request. In the meantime, power has come back intermittently, but the current seems to be weak, and now the switch that controlled my garbage disposal now controls power to a light in my living room and the power to the tv. And my garbage disposal isn't working at all.

My question is what happened? Can a switch be reset like that without some kind of human intervention? It seems odd that a light switch would just start controlling power to outlets in another room.
posted by dortmunder to Home & Garden (32 answers total) 3 users marked this as a favorite
What made you think the current was "weak?"

It sounds like rewiring is being done elsewhere in your building. Do you have a common wall with a neighbor, and could you ask them if they've noticed similar events?
posted by werkzeuger at 6:30 AM on November 11, 2012

Thinking some more...I'm speculating that there could be an intermittent short and poor grounding in the garbage disposal that's leaking current somehow to the living room outlets. A long shot, but a potentially dangerous one. You really need a licensed electrician - not the building super or a handyperson - to figure out what's going on. Was your garbage disposal working properly before all this started?
posted by werkzeuger at 6:39 AM on November 11, 2012

Response by poster: Yes. It was. Everything was working properly. Then, overnight it went out. Now it's back on, but flickering intermittently. And I don't know why I said I don't have a circuit breaker box: I do, and none of the breakers have been tripped. I'm going to be shutting off power to the disposal and probably the living room until this gets sorted out.
posted by dortmunder at 6:43 AM on November 11, 2012

Seconding werkzeuger. If your apartment was doing major electrical work like that, they'd have probably told you. Also, a garbage disposal is usually on a very different circuit than a light (at least, given current code where disposals are given their own). Flickering usually means there's a short. Like he said, Danger, although the danger is most likely wherever the breaker box for your part of the apartment complex is (water leaking in?), and I bet your neighbors are having similar problems. I'd tell your landlord/maintenance person ASAP.
posted by hanoixan at 6:45 AM on November 11, 2012

Response by poster: I worked from home Thursday and Friday, and I was home a good part of yesterday, and I'm pretty sure there was no maintenance being done, and I just talked to an upstairs neighbor, and they're not having problems, but we don't share a wall.
posted by dortmunder at 6:52 AM on November 11, 2012

Yeah, flickering could well mean an arcing short somewhere. Definitely leave the switch for the disposal in the "off" position and don't use sensitive electronic stuff on the suspect outlets.
posted by werkzeuger at 7:01 AM on November 11, 2012

Try flipping all of the breakers off and back on, and see if this changes anything. It's very unlikely that it will, but you never know, and if it does, than you know you might have a bad breaker in there.
posted by markblasco at 7:02 AM on November 11, 2012

OP if you learn what the problem is, would you update this? Your situation is bizarre enough that I really want to know what's going on.
posted by werkzeuger at 7:03 AM on November 11, 2012

You keep updating faster than I can type . . . .

Kill power to the disposal & living room & don't touch.

Without info about how your building's electrical service is set up, it's hard to give a complete answer - getting a building super in who's familiar with the building is probably more useful than AskMe. One neighbor not having problems may or may not be significant, depending on how power gets into the building & is distributed.

Half your power on, half off, my first guess would be that you've got a problem with the service into your apartment. This could be at the transformer & lines outside your building, at the master breaker/fuse box inside the building, or in the wires from that master switch to your apartment's breakers.

Power back on but weak suggests the problem is at the outside transformer or wires into the building. Go outside, see if any work is being done in your neighborhood. Like guys in bucket trucks from your local electrical utility.

werkzeuger is right about the possible leaking current causing the apparent "rewiring" - the question is whether it's in your apartment or whether it's caused by something going on outside your apartment.
posted by soundguy99 at 7:10 AM on November 11, 2012

At first this sounded like you lost one leg of your 240V service, leaving only the circuits on the other leg live. But the disposal switch oddity says something else/more is in play here. If you can't get maintenance to show up quickly, consider calling the power company. At least then they can isolate the problem to either your building or their equipment.
posted by tommasz at 7:29 AM on November 11, 2012

Response by poster: OP if you learn what the problem is, would you update this? Your situation is bizarre enough that I really want to know what's going on.

I will. It will be a while, though. I can't reach any building staff, and they won't be in until afternoon today.
posted by dortmunder at 7:35 AM on November 11, 2012

Kill power to the disposal & living room & don't touch.

Yup. I can't remember if garbage disposals are double insulated or what, but you might want to minimize your use of the kitchen sink. If you feel even the slightest tickle from anything metal anywhere in the apartment but especially the kitchen sink or plumbing, you've got an emergency and need immediate help.
posted by werkzeuger at 8:47 AM on November 11, 2012

And if you talk to the electricians ask them if perhaps a neutral is disconnected in a junction somewhere or just barely touching. These symptoms would be consistent (depending on how your place is wired) with a neutral coming loose in a junction and just barely touching the connecting neutrals. When it's disconnected, again depending on the exact wiring diagram, you can get neutral return from 1 circuit ending up partially (weak current you said) returning through 1 leg of a 220 / 240 circuit OR even from the hot leg of a 110 if the malfunctioning circuit and the one I'm describing are powered from different legs of the feed.

But echoing all - turn 'em off and wait for the electrician. I have a screwdriver which is burned 1/2 way through the shaft from just such a problem. AND my hand hair took a few weeks to grow back - not something to play with.
posted by BrooksCooper at 8:48 AM on November 11, 2012 [1 favorite]

At first this sounded like you lost one leg of your 240V service, leaving only the circuits on the other leg live. But the disposal switch oddity says something else/more is in play here. If you can't get maintenance to show up quickly, consider calling the power company. At least then they can isolate the problem to either your building or their equipment.

It does sound like one leg is out. Power could be feeding back through some 240v appliance. Either in your apartment, or somewhere else in the building.

The first step is to turn all your breakers off, and then turn them back on one at a time. If that doesn't fix it, turn them all back off again and see if you can access the power distribution point in the building where all the power meters are. Find your meter, and cycle the breaker that is near your meter off and on, and then try again. Sometimes breakers can be tripped without the switch popping over to the middle position. Especially the breakers for 240v circuits where it is two breakers ganged together- if one leg trips, the other leg holds it in the "looks on" position.

If that doesn't fix it, the next step would be to turn everything off again, and then only turn on the single breakers. See if everything works normally. If it does, then turn on (one of) the double breakers- electric stove, or electric dryer or hvac unit. You'll probably find that turning one of them on will cause the other stuff to go weird again. If you can unplug that appliance, unplug it, and then turn everything off and on again. If the power goes back to normal, you can probably bet that that appliance is the culprit. If it still trips with the appliance unplugged, something has gone bad in the wiring or there is a bad breaker.
posted by gjc at 8:49 AM on November 11, 2012

You know that the circuit that the garbage disposal is involved, whose wiring is low in a kitchen wall that also contains plumbing. That causes me to consider the possibility that the problem may be water related.

Check for dampness under the kitchen sink.

Do you live on the ground floor? Has there been a lot of rain in your location recently? Is the kitchen sink on an exterior or interior wall?
posted by perspicio at 8:51 AM on November 11, 2012

OP is this North America or somewhere else?
posted by werkzeuger at 8:51 AM on November 11, 2012

Response by poster: I'm in North America. And things are really weird.

My refrigerator is on, but barely. The light inside is very dim and the refrigerator itself keeps stopping and starting. When it does, I've found the TV flickers. And at one point, while I was testing everything, I could turn on my tv, but not my xbox, and they're both plugged into the same surge protector, so they should be drawing power from the same outlet. I eventually got the xbox to boot up, so the device itself isn't broken.

Oh, and there is no leaking around the sink. Dry as a bone underneath.
posted by dortmunder at 9:05 AM on November 11, 2012

Something is seriously wrong with the electrical service to your apartment. If you have an emergency number for your bldg management that you haven't already tried, now's the time to use it. Also, you're risking permanent damage to your electronic stuff. Unplug them, unless you have a receptacle you know is not having problems.
posted by werkzeuger at 9:11 AM on November 11, 2012

You realllllly need to unplug anything you don't want to fry. Like, now. The fridge, the stove, all your electronics. Don't wait, go do it now.
posted by zug at 9:21 AM on November 11, 2012

nthing the suggestion to unplug your electronic stuff. Do it now.
posted by perspicio at 9:22 AM on November 11, 2012

I second the idea that this is a potential emergency. If it were my place, I'd kill all the breakers and call the emergency number for maintenance.
posted by zug at 9:22 AM on November 11, 2012


Do you live on the ground floor? Has there been a lot of rain in your location recently? Is the kitchen sink on an exterior or interior wall?


Is the TV room adjacent to the kitchen? Are the TV, the fridge and/or the garbage disposal plugged into the same wall?

It's hard to zero in on the problem without actually being there unless we can rule some things out. Detailed information would be helpful.
posted by perspicio at 9:25 AM on November 11, 2012

Not potential emergency, this is an emergency. Either you have lost the neutral, which can cause 120V circuits to go to well over 240V, or you have lost a leg of service and are risking damage to basically everything electrical in your apartment. Whatever came loose may well be arcing and could start a fire any minute now.

You need to turn the power off now and get an electrician at your location literally as soon as humanly possible. This is serious business.

While those of us who answer here on AskMe are the sort to not let go of a problem, you need to quit asking us and ask an expert who has seen your electrical system.
posted by wierdo at 9:30 AM on November 11, 2012 [2 favorites]

Yeah, seriously, quit fooling with this stuff, you can easily damage your electronics or yourself.

No disrespect to perspicio, but this really needs to be looked at by someone in person. There are too many variables at play here & I don't think you have the electrical knowledge or enough info about your building to accurately give us enough of a detailed description that we could provide you real help.

My only addition to wierdo's post above is that you will probably need to get whatever emergency building maintenance person you have in first, then THEY can call the electrician.

Do this ASAP - even if it winds up being not a super-serious problem, it's above your pay grade.
posted by soundguy99 at 9:40 AM on November 11, 2012

Ya, you've got a serious problem like weirdo outlined. Unplug anything you can to protect it from the undervoltage (your fridge especially); turn off anything you can't unplug and then wait for the electrician. If you do this I think your chances of a fire are low.

It probably won't take long to fix as it's likely isolated to a single connection somewhere but it'll be impossible to diagnose specifically without taking a look and putting a meter on some wires.

PS: Here in Canada it is essentially illegal to not make the circuit breaker panel accessible to a tenant unless the panel is in another tenant's suite. If your panel is in an electrical room getting a key to that room would be a good thing to badger your landlord about.
posted by Mitheral at 9:45 AM on November 11, 2012

Thinking about your description more, I'm almost certain it's an open neutral. Garbage disposals and lights are both 120V loads. IIRC, a lost leg will present as lights/outlets that only work if your dryer or (electric) hot water heater or (electric) stove are "on". If you kill all the 240V breakers in that scenario, (about) half your 120V loads should work normally and the other half should be off.

Let's hope your 240V appliances don't have any electrical faults at the moment. If they do and you touch them, I hope there's someone handy to start CPR as soon as you're away from the live appliance. Plus it's a fire hazard in the appliance itself, not to mention the fire hazard from the possibly arcing loose neutral wire or the fire hazard that may presently be your telephone and cable wiring, depending on where/how they're bonded to ground and what loads are on in your apartment.
posted by wierdo at 9:56 AM on November 11, 2012

Definitely no argument here about taking all appropriate safety precautions. I agree with wierdo & others that you need to get help as quickly as possible. If you didn't express it as an urgent need when you called in the request, call back and do so. Hopefully you have also killed the affected breakers by now too, and unplugged your stuff. (If not, use electrically insulated/rubber gloves when doing so.)

Please don't let urgency translate to panic though. Just make sure the breakers are off and your stuff is unplugged, and don't mess with it. It would probably be a good idea to let your other neighbors know what's going on, too. Chances are you already know where all the building stairwells/exits are, etc.

In my opinion, someone should remain present at the apartment, if for no other reason than that if an electrical fire did start, they would notice right away and be able to alert your neighbors. If the breakers are off, the chances of that are extremely low, but it's still good to have a plan.

Aside from that, while you wait for the pros, we can try to figure out what's going on. Not by tinkering with anything, but by thinking & talking about it.
posted by perspicio at 10:02 AM on November 11, 2012 [2 favorites]

I had a house whose main line from the street was only partially connected, which meant that the weak connection gradually deteriorated. It was fine one day, the next it started doing all kinds of weird things in the house that did not match my understanding of house wiring or electricity at all.
posted by cmoj at 10:10 AM on November 11, 2012

We had a very similar question before.

The answer turned out to be that a 220-240 volt appliance (which is connected to both legs) was feeding power from one leg of a service into the other leg which had a tripped circuit breaker.

The problem was resolved completely by resetting the breaker.
posted by jamjam at 10:38 AM on November 11, 2012 [2 favorites]

Good find, jamjam, I knew I'd seen an AskMe along these lines that turned out not to be a floating neutral after all. And that explanation would explain the presumably-220v garbage disposal as well. (The situation isn't entirely unlike a floating neutral really.) The problem would only be resolved completely by adding the pin to correctly gang the two legs' breakers together, though. Otherwise the problem will just recur and be unsafe each time.
posted by hattifattener at 1:43 PM on November 11, 2012

The whole system is acting like you're missing one 'legs' on the 3-phase power coming into your building. A missing leg will cause all kinds of weird behavior just like you're describing. The building maintenance people should be able to resolve the issue extremely quickly by turning the missing leg back on.
posted by Confess, Fletch at 1:46 PM on November 11, 2012

Response by poster: Ok, here's the update: My apartment guys looked at everything today and determined they needed to call an electrician. It was one of the outside breakers that had worn out. An electrician came out this afternoon and replaced it. Everything is working fine now, even the garbage disposal.
posted by dortmunder at 12:49 PM on November 12, 2012 [1 favorite]

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