My apartment is suddenly in a state of electrical chaos
June 10, 2012 7:04 PM   Subscribe

I just installed a new lightswitch in my bathroom. Now, when I turn my living room air conditioner OFF, the power in most of my apartment goes out. And even when the AC is on, the power level is extremely low. WTF???

I'm competent to do basic home repairs. I know enough about electricity to have successfully installed wall light fixtures and hanging lamps many times with no mishaps. So I figured I was qualified to replace a lightswitch. But I'm totally bewildered by what has happened subsequently.

The lightswitch in my bathroom developed a mechanical defect months ago (it would flip itself into the on position). I've been using pieces of tape to keep it in the off position, but clearly it needed replacing. This evening, I switched off the breaker controlling my bathroom -- which also happens to control my living room and back bedroom -- and proceeded to take out the old bathroom lightswitch and install a new one.

I wired up the new switch, turned the breaker on, and turned the switch on (with a screwdriver handle, in case I'd made any kind of wiring mistake). There was a small ZAP and some sparks, and the bathroom lights did not turn on. I turned the breaker off again, took the faceplate off the switch, and realized that I needed to wrap some electrical tape around the switch unit, to cover the terminal screws holding the wires in place so that they didn't contact the metal box around the switch. (The old switch had tape wrapped around it.) I wrapped the switch generously in electrical tape, and when I turned the power back on, the new switch worked...

But it seemed like the bathroom lights were a bit dim. In fact, I noticed that lights in all the rooms on that circuit were kind of dim. Then I noticed that the living room AC -- a wall unit on a separate circuit from the rest of the living room -- seemed to be ofw. I had had it on while replacing the switch, and hadn't noticed it going off. But the AC knob was still in the on position. I turned the knob to the off position -- and the lights promptly went out in the living room, bathroom, and back bedroom!

Subsequently, I've discovered these further facts:

1. With the AC knob in the on position, the power in the living room, bathroom, and back bedroom comes back on -- again, at a low level. It's low enough that my desktop PC, in the back bedroom, turned itself off after a few minutes; I started this post on that computer, but am now rewriting it on my netbook.

2. The living room AC is actually on -- barely. I can hear the fan and compressor operating very faintly.

3. This freakish power issue is also affecting my refrigerator -- which is on its own separate circuit! The fridge seems to be cycling on and off every few minutes. When it's on, the light in the back bedroom gets brighter, as does the work light I currently have plugged into my microwave/toaster outlet in my kitchen (which itself is supposed to be on yet another separate circuit). Even when the fridge is on, I suspect it's not at full power -- the internal light seems a bit dim. It's possible that this cycling behavior is actually being triggered by the AC cycling on and off -- I don't know. This can't be good for my food -- or for my fridge!

4. The power cycling issue is affecting my cable modem as well -- I seem to lose my internet connection when the power level is super-low, which happens every few minutes.

What in bloody hell is going on!?
posted by Artifice_Eternity to Home & Garden (40 answers total) 9 users marked this as a favorite
Dimness = badness. Please switch the breaker off for this switch NOW.
posted by zippy at 7:08 PM on June 10, 2012

Call an electrician NOW. Cut the main power. Keeping it on is begging to catch your place on fire.
posted by chrisfromthelc at 7:15 PM on June 10, 2012 [1 favorite]

Response by poster: Zippy, per your advice, I've just switched off the living room/bathroom/back bedroom breaker. This means I have no light in most of my apartment, and no internet connection (luckily I have a neighbor with unsecured wi-fi).

I still have the AC turned on. If I turn it off, the worklight on the microwave/toaster circuit goes out, and the fridge goes off. With the AC on, the fridge is still cycling frequently, and the again, the worklight gets dim when the fridge goes off.

I just can't understand how my AC is suddenly controlling the power for pretty much the rest of the apartment.
posted by Artifice_Eternity at 7:15 PM on June 10, 2012

Response by poster: Now I've turned the AC off, since clearly it seems to be doing something bad. Of course my fridge is now off as well.

So... can anyone recommend a reliable electrician at 10:15 pm on a Sunday night in Brooklyn?
posted by Artifice_Eternity at 7:17 PM on June 10, 2012

If you value your life and those of your neighbours, please step away from the wiring and do not touch it until an electrician arrives.

Also, get your breakers/panel checked out. Something should have blown/tripped long before you got into this situation. You have pretty much an unmitigated electrical disaster on your hands at the moment: if it means you have to go 24 hours without lights or AC or internet, so be it.
posted by unSane at 7:25 PM on June 10, 2012 [1 favorite]

Response by poster: You have pretty much an unmitigated electrical disaster on your hands at the moment

Thanks, I noticed!

I'm ready to call in a pro. Can anyone recommend someone in Brooklyn, NY?
posted by Artifice_Eternity at 7:26 PM on June 10, 2012

Call the power company, ask them for help / recommended electrical service.
posted by jenkinsEar at 7:28 PM on June 10, 2012 [2 favorites]

I don't think this is as severe as everyone else says, but yeah, call in a pro because you're over your head.

I've used these guys before; they're nearby.
posted by zvs at 7:30 PM on June 10, 2012

Sounds like you've somehow got the lights wired in series with the AC, but how that's happening I don't have much idea.

I don't live in your state let alone neighborhood, so I can't recommend anyone, but wanted to comment on this:

I needed to wrap some electrical tape around the switch unit, to cover the terminal screws holding the wires in place so that they didn't contact the metal box around the switch. (The old switch had tape wrapped around it.)

That is nutty. There is absolutely no legal, safe situation that would require electrical tape to insulate the switch's terminals from the box. If the box is that small, it needs to be torn out of the wall, stomped on and then nailed to a fencepost to be used for target practice.
posted by jon1270 at 7:35 PM on June 10, 2012 [5 favorites]

Can you go to sleep without power tonight and call an electrician in the morning? (-captain obvious)
posted by pintapicasso at 7:38 PM on June 10, 2012

My guess is you have a neutral or ground wire that's not connected to the breaker box any more. As a result, power is flowing from one phase, through the AC to the neutral, then through other loads to the other phase. Or something like that.

Unfortunately it's pretty dangerous to have a floating neutral or ground. So calling an electrician is a good idea unless you know exactly what just happened. From your description it's hard to tell whether you messed something up or whether you simply encountered some existing horrible wiring.

(Also, FWIW, it shouldn't be necessary to tape up the switch like that to keep it from shorting to its box.)
posted by hattifattener at 7:38 PM on June 10, 2012 [3 favorites]

Response by poster: jon1270 and hattifattener: The taped-up switch seemed weird to me, but it had been that way at least since we bought this place (4+ years ago). I guess I need to remember that just because something has "always" been a certain way doesn't mean it's actually safe or up to code.
posted by Artifice_Eternity at 7:41 PM on June 10, 2012

I assume you own your apartment? Because otherwise you should be giving your LL a heads-up.

I've used WCK Electric in the past, they've done good work.

FWIW, if this is an old building, there's no telling what kind of insanity may lurk behind those walls. There's a hundred years of bad wiring jobs in Brooklyn buildings.
posted by swngnmonk at 7:41 PM on June 10, 2012

Ah, you own it. nm on that first concern.
posted by swngnmonk at 7:42 PM on June 10, 2012

Response by poster: Yeah, I own it. It was built in 1965, and till now I'd always thought that the wiring was reasonably up to modern standards.
posted by Artifice_Eternity at 7:46 PM on June 10, 2012

When you had your "small ZAP and some sparks" and the bathroom light didn't turn on, did you actually have to turn the breaker off yourself before working on the switch again, or did you merely have to check that it had already tripped?

I suspect that that breaker no longer responds properly to overloads, functioning now as a purely manual switch, and that your ZAP actually burned out the apartment's neutral supply wire upstream of your breaker box, with the result that the neutral wire inside your apartment is now serving only to connect your aircon+fridge on one phase in series with your lights and power outlets on the other.
posted by flabdablet at 7:56 PM on June 10, 2012 [2 favorites]

Also, wiring that's reasonably up to modern standards would not include a metal switch box that's so small as to short to the terminal screws on the switches. That's just nuts.
posted by flabdablet at 7:57 PM on June 10, 2012

Stepping away is probably the best bet at this stage.

Just a question, with the breaker for the AC off and the breaker for the switch off, do you still have problems with your fridge? If so, I would say you have a problem in the box or upstream.

I would keep flipping breakers off until I found an outlet which worked reliably for the fridge and then call in the professionals. This might mean you need to plug your fridge into a couple of different outlets as you turn off the circuits...If you need to turn them all off (i.e. you can't find one circuit which seems to work) then I would hit the main and call it a night...
posted by NoDef at 7:59 PM on June 10, 2012 [1 favorite]

Response by poster: flabdablet: I believe that the breaker tripped when I had the short... but to be honest, I'm not entirely sure. Your theory about the neutral supply wire is very interesting.

NoDef: The fridge is off at this point (even tho the fridge circuit is on). The fridge won't run if the AC is off... and I turned the AC off a while ago, and am leery of turning it back on till this whole mess is sorted out.
posted by Artifice_Eternity at 8:04 PM on June 10, 2012

Response by poster: P.S. NoDef, thanks a million for the suggestion that I try plugging the fridge into another outlet! That hadn't occurred to me!

I just ran an extension cord from the fridge to an outlet on the other side of the kitchen, and the fridge seems to be running off of it at full power. That is a huge weight off my mind. The cost of getting this mess sorted out will be high enough, without also having to buy a fridge full of new food.
posted by Artifice_Eternity at 8:18 PM on June 10, 2012

If the fridge works fine from a different outlet, I would turn off the breakers for the switch, the outlet for the AC, and the original outlet for the fridge and let the pros work it out in the morning. (I would also unplug the AC and anything else on these circuits, but that's just me)

Don't assume that just because the switch and/or AC are turned off that they won't cause a problem while you are sleeping - turn them all off at the breakers and (again me) unplug everything on these circuits...
posted by NoDef at 8:28 PM on June 10, 2012

Response by poster: Thanks. I already had some of the relevant breakers off, but I've gone ahead and turned them all off, and unplugged the AC.
posted by Artifice_Eternity at 8:37 PM on June 10, 2012

OK, so if the fridge is still capable of running at full power then your apartment still has a functioning neutral supply wire. The behavior of the aircon and the lights still says that those are now wired in series, and the only way that makes any sense at all is if their hot sides are on two different phases and their neutral is common and floating. So it sounds like some of your apartment has neutral wiring that doesn't go all the way back to the neutral bar at the breaker box. I can't see how that could possibly be up to code.

It might even be as awful as having only hot-side wiring, relying on earthed conduits for a neutral return, some portion of which are now no longer earthed.
posted by flabdablet at 8:47 PM on June 10, 2012 [1 favorite]

It occurred to me that if the AC is on a 240v circuit, its breaker is double tapped and shared with the bathroom lights, and that breaker either off or has failed open, then you could get the behavior that A_E describes without any floating grounds or neutrals. Still not a great thing though.
posted by hattifattener at 8:55 PM on June 10, 2012

I'm not seeing how that works. Care to attempt an ASCII wiring diagram?
posted by flabdablet at 9:00 PM on June 10, 2012

Response by poster: hattifattener: Yes, I'm pretty sure the AC is on a 240v circuit. It's got a plug with 2 horizontal (rather than vertical) prongs, plus a ground prong. Also, there are 2 adjacent breaker switches that control the AC -- they both have to be on for the AC to work.
posted by Artifice_Eternity at 9:02 PM on June 10, 2012

I think that zap did some very weird things.

For one, it melted the common neutral downstream of the AC and fridge and the bathroom, so that none of them can get (directly) to neutral any longer.

But at the same time, it welded the hot side of the bathroom circuit to neutral past the melted point. And I think it must also have fried the circuit breaker for the bathroom, so that no voltage is getting from the breaker box directly to the bathroom.

That means that the fridge and the AC can get to neutral by going backwards through the bathroom circuit, which is now welded on the hot side to the neutral below the melt and connected by its neutral side to the neutral wire above the melt, but which is isolated from the breaker box by the kaput breaker.

That also means that the bathroom circuit only gets juice when either one or both of the AC and fridge are on, because the bathroom gets juice that's already passed through the AC of fridge.

But that's like putting a big resistor (the bathroom stuff) in series with your fridge and AC, and so neither of their compressors will work on the low voltage now available to them, which means your fridge isn't cooling.

Plug your fridge into a circuit on the other leg (one that makes the light as bright as it should be) and call in an electrician.
posted by jamjam at 9:36 PM on June 10, 2012 [1 favorite]

I'm blanking on the technical terms, which I realize isn't much help, but you may need a separate breaker/line installed for your AC. We ran into the same issue at my Mom's house. The AC simply overloaded the available circuits. For an electrician, it's an easy job. For an amateur, step away from the wires and call an electrician (which I realize you already understand).
posted by katemcd at 10:13 PM on June 10, 2012

Response by poster: Yep. I am leaving well enough alone and calling a pro in the morning. At least I now have a working fridge, lights in 2 rooms of the house, and an internet connection (I ran an extension cord from a working outlet to the room where my modem and router are).

Thanks for all the advice and ideas!
posted by Artifice_Eternity at 10:27 PM on June 10, 2012

And of course you'll come back here and report what the electrician finds, yes? Inquiring minds must know!
posted by flabdablet at 3:09 AM on June 11, 2012 [5 favorites]

Make the electrician post!
posted by snuffleupagus at 5:34 AM on June 11, 2012 [1 favorite]

Response by poster: OK, I have calls out to a few different electricians. I'm hoping to set up an appointment with one of them shortly. I'll definitely come back and post about all this weirdness when it's resolved!
posted by Artifice_Eternity at 8:28 AM on June 11, 2012

flabdablet: In this theory current would flow from Φ1, through the AC, to Φ2, which is off/tripped/open, but if Φ2's breaker is double-tapped for use in the bathroom, current would then flow through that breaker's other hot line to the bathroom loads. I'm just trying to think of an explanation that involves fewer unlikely failures. Anyway, we should know soon enough once A_E's electrician examines it.
posted by hattifattener at 9:37 AM on June 11, 2012

Also, there are 2 adjacent breaker switches that control the AC -- they both have to be on for the AC to work.

So, does one of those control the bathroom as well?
posted by flabdablet at 11:07 AM on June 11, 2012

wait wait wait I think I have it!

The aircon is 240V, so it's wired between the two opposite-phase supply lines Φ1 and Φ2; it doesn't have a neutral. The hot wire to the circuits that are still working right will connected to one of those phases, say Φ1. The bathroom and the other things that are currently wonky will be supplied from Φ2. But the Φ2 wire is now disconnected from the supply line and floating, which means that it picks up a weakened version of Φ1 via your apartment's aircon when that's switched on. This is the scenario as envisaged by hattifattener, and I think it's probably quite right.

What I now suspect is that your ZAP tripped not only your apartment's bathroom breaker, but the building's main Φ1 supply breaker as well.

If I'm right, then Φ2 is floating within the whole building, and if you ask your neighbors if their electricity is acting weird, they will say yes. And I'll bet that all your sparky is going to need to do to un-weird things is reset a breaker inside the building's supply cabinet before installing a proper switch box in your bathroom.
posted by flabdablet at 11:35 AM on June 11, 2012

Response by poster: UPDATE: All is well!

zvs, thanks for recommending Ral-Bar Electric; of the 4 places I called, they got back to me quickest today, and since they had a couple of guys in my area on a job today, they were able to send them over this afternoon.

They opened up the bathroom lightswitch, the apartment's switchbox, and the AC power outlet, and didn't find any obvious problems. Then we went downstairs to look at the main breaker for my apartment. I didn't have access to this last night -- the building's super is on vacation -- but the part-time doorman was here today, and was able to get us into the meter room where the breakers for the whole building are.

And my breaker was tripped. Evidently the breakers in my apartment's own box, or at least the one for the bathroom, are not as responsive as they could be... so the main apartment breaker tripped, instead of the local breaker, when I had the short circuit during the lightswitch installation.

The electrician said, more or less as some folks suggested above, that the weirdness last night was caused by my 240v air conditioner feeding power back into other circuits within the apartment. He also said that I did in fact wire the new bathroom lightswitch correctly. It's nice to know that I'm not a complete incompetent.

I'm not sure why the power in a couple of rooms was never affected by any of this -- maybe there are 2 separate breakers for my apartment downstairs? I'll have to check.

The guys from Ral-Bar charged me $168 for an hour of poking around, and replacing the faceplate on the bathroom lightswitch (which was not in great shape). But I consider it money well spent to get them in here quickly, and to verify that there are no serious underlying problems with my apartment's wiring. As I told them, I'm happy to have my power on again less than 24 hours after it went out, without having to endure having any walls ripped open, or any other drastic interventions (or catastrophes).

Thanks again to all who offered advice!
posted by Artifice_Eternity at 1:26 PM on June 11, 2012 [3 favorites]

Best answer: Apparently only one leg of the main breaker tripped leaving the other leg hot. The 120V circuits on the hot leg operated normally through the neutral wire as you saw. When you turn on the A/C the hot 120V leg back feeds into the dead 120V leg. The circuits on this leg are in series with the A/C motor so are dim. Meanwhile the circuits are the hot leg are working just fine.

This is a dangerous situation. The two legs of the main breaker should be ganged together with a clip so that if one leg trips, the other trips as well, preventing a back feed situation. I hope the electricians replaced the gang clip on the two main breakers.
posted by JackFlash at 4:02 PM on June 11, 2012

Response by poster: JackFlash: Thanks for your succinct diagnosis. What you say makes sense. No modifications were made to the main breakers today.

I'm pretty sure the building's management company and/or co-op board would insist on approving any modifications to the main breaker. I will take this up with them.
posted by Artifice_Eternity at 7:32 PM on June 11, 2012

Evidently the breakers in my apartment's own box, or at least the one for the bathroom, are not as responsive as they could be... so the main apartment breaker tripped, instead of the local breaker, when I had the short circuit during the lightswitch installation

A dead short could easily have drawn enough current to trip both (remember you weren't sure if the bathroom one had actually tripped). Once a breaker has detected an overload the rest of the tripping process is purely mechanical and can't be stopped, even if the overload goes away quickly as an upstream breaker cuts it off.
posted by flabdablet at 9:12 PM on June 11, 2012

Agree: circuit breakers are super cheap, relatively, and they should probably be replaced.
posted by gjc at 3:20 AM on June 12, 2012

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