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mikemcd 09-08-2011 06:36 PM

Breaker tripping without load after heavy rain
Think I might know the first place to look to possibly fix this, but I'm an electrical novice so I figured I ought to get some opinions before I do anything.

I live in NJ, and between Irene and Lee we've been getting dumped on with rain lately. I've been in my house over 2 years without any electrical issues, so I think it's more than a coincidence that after last night's heavy rain all of a sudden a breaker issue popped up.

I have a breaker that won't stay on, and it controls the garage lights and outlets (not the door), a bedroom above the garage (lights and outlets), and the bathroom next to the bedroom (lights and outlets). Outside of the garage there's a motion light over the driveway, also on this same breaker.

So of course my guess is that after the heavy rain, maybe that outside motion light isn't sealed up as tight as I thought, some water got in and it's tripping the breaker. It's an old light and needs to be replaced anyway, so I figure that's where I'll start.

But again, being an electrical novice, I'm also wondering if by chance I'm looking in the wrong direction. Any other opinions on this? Should I be looking elsewhere for a possible problem?

joed 09-08-2011 07:01 PM

That would be a good place to start. Has anything else changed on the circuit? Any new devices added? heater? AC?
Does it trip instantly or does it take a some time? How much time?

mikemcd 09-08-2011 07:11 PM

Nothing has changed, it's the same old stuff on the circuit. It trips instantly, usually. I tried resetting it a few times and sometimes it would stay on for a minute, but most times it immediately flipped back off.

bpm 09-08-2011 07:30 PM

If you feel comfortable working inside your panel, you can shut off the breaker, then disconnect the wire from it. Try to reset the breaker with the wire removed. If it won't reset, you have a bad breaker. If it does, you have a short somewhere.

Thadius856 09-08-2011 11:24 PM

Any outdoor lighting needs to be on a GFCI for this exact reason.

I strongly recommend adding GFCI protection on this circuit when you replace the outdoor light.

The outdoor light does seem to be the most likely cause, but there could be other reasons as well. The fact that it powers the garage could be key as well.

(Edit: To be clear, I say "for this exact reason" being to prevent a potentially lethal shock under circumstances where water could cause a grounding through you)

mikemcd 09-10-2011 11:30 AM

Thanks for the feedback, guys.

I've narrowed down the problem a bit, although I think the situation is worse than just a little moisture in a box.

The outdoor light that I figured was the cause of the problem is, in fact, the problem. With the garage door open, I can flip the breaker and hear the outdoor light make a pop sound just before the breaker trips.

The worse situation is that when I get near the light, I smell something burning.

So I took the light down and cleaned around the box, which was full of old sealer and some mold. There are definite signs of moisture. Here's some photos of what I've got now:

Even with the light removed, the box somewhat cleaned, and no visible moisture or water still in there, the breaker trips and I smell something burning. The wiring looks pretty old. Wondering if that's the issue.

Just looking for some advice here. Any suggestions?

Thadius856 09-10-2011 11:53 AM

You need to start working backwards up the circuit.

Disconnect the nearest receptacle or junction that you suspect to be on this circuit. It should be fairly obvious, since the breaker won't stay on, that it should be dead. See if the breaker will turn on with that leg disconnected.

The problem is that the non-metallic cabling used on this leg of the circuit is (from what I recall reading, anyway) NOT, and I repeat, absolutely not rated, intended for, or even safe for use in wet locations. If there's a break anywhere in the individual conductors' sheathing anywhere up the line (I suspect there is), this soaked jacketing is going to present electricity a pathway before it gets to the end of the cable.

I don't understand why somebody would go to the lengths required to use an outdoor box, but then use this cable.

Edit: It that sand in the picture? How is this even possible?

mikemcd 09-10-2011 02:29 PM

Thanks, Thadius. I did exactly that and got the breaker to stay on with the junction box directly above the breaker box disconnected. I verified that the outdoor wires were dead with a volt sensor. Breaker stays on, those wires are off. Sounds like you're right, there's likely a break along that wire.

The rest of the circuit is still off, I'm assuming because the junction I disconnected was the first in the circuit going to the other outlets in that room and on to the bathroom.

So the fix for this seems to be this (correct me if I'm wrong): Run new wire from the box up to the disconnected junction to power that room and the rest of the circuit. Put a new GFI breaker in for the outdoor light, run new wire for that as well.

I don't think it's sand, BTW. It's some sort of corrosion. Likely also a result of the moisture in the box.

Thadius856 09-10-2011 03:16 PM

That fix doesn't seem quite right to me.

I imagined your circuit as running from the panel, powering a few rooms, then branching at the junction you disconnected to continue on somewhere else and to power that light. Under these assumptions, that fix will only accomplish something if power went to the junction box, then to the light, and from the light to the rest of the circuit. But that isn't what I see in the picture, and that would mean that everything downstream would be controlled by that light's switch.

It should be enough to simply disconnect the light's run at that junction, assuming that's where it branches.

Once you can get the rest of the circuit to stay on, head down to the hardware store or home improvement store. You'll want to buy outdoor-rated NM (Romex) by-the-foot. If it's a 15 amp circuit, you'll want 14g, if it's a 20 amp circuit, you'll want 12g. You may have to buy 3-wire or 4-wire in order to get it by the foot, but that's fine as long as you leave the extra conductors unused on both ends. I wouldn't waste your money buying a whole spool of outdoor-rated NM.

If it's a short run, you may be able to get away with taping one end of the new cable to one end of the old cable, and pulling both through from the other side. Otherwise you may have to open the wall to replace it. Take your time - everything's to-code without that light connected.

Best of luck! I'll keep an eye on this thread. :)

mikemcd 09-12-2011 02:01 PM

You're right. The box I disconnected wasn't the box I really needed. It interrupted the circuit but wasn't where I really needed to be.

There's a switch in the garage that controls the outdoor light, and runs to a 3-way switch for an indoor garage light. I never knew that these switches affected the outdoor light as well as the indoor light. But this does make it much easier to isolate the outdoor light. I've got that switch off, and the breaker stays on. I'm going to run new wire and a GFI for the outdoor light.

Thanks for the help!

jbfan 09-12-2011 02:07 PM

Gfci is not required for outside lights.

Thadius856 09-12-2011 02:43 PM

Seems that only receptacles are required to be protected by GFCI outdoors per NEC 2008.

My mistake. It still wouldn't hurt to have GFCI protection upstream. It would also be much easier to disconnect juice to that light if it was needed in the future.

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