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Alex
Alex, Master Electrician
Category: Electrical
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Experience:  Owner of independent electrical contracting company. Licensed Electrical Contractor in CT.
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Breaker Tripped When Turning Light Off

I have a circuit breaker... Show More
I have a circuit breaker that has started getting tripped when I turn a light off. This ciruit has both indoor lights and outdoor lights on it. It only trips when we turn the outside lights off. I've checked the outside light switch and aside from being wired backwards (it says off, when its actually on), everything looked ok to me (I'm not sure how much that's really worth). Thanks for your help.
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Hello, have you replaced the switch or light?
Customer reply replied 5 years ago.

No.

When did that start? Did you have a storm recently?
Customer reply replied 5 years ago.
No. We first saw the issue Monday and it had rained a little during the day, but nothing severe. At first I thought we had just tripped a breaker, but when I went to go reset it, it would not reset. After a few minutes I went back to reset it and it did (outside lights were off). We did not turn the lights on all week, until yesterday when my 5 yr old accidentally flipped the switch. At that point the lights came on, but when we turned them off, it tripped the breaker and it will not reset unless we have the outside lights on. I've checked the switch and nothing looks out of the ordinary to me (no loose wires or burning). I took the bulbs out of the outside fixtures and checked for loose wires (I didn't see anything). I have not taken the fixtures themselves out (these lights are recessed in our porch. Not to muddy the water here, but there is one other post light that I think is on this switch. I don't know for sure because its never worked (we moved in about 20 months ago). There is also an outside receptacle that runs out to a flower bed in our yard that appears to be on this circuit (not the switch that's tripping everything). Let me know if you need any additional information or would like pictures of anything. Thanks.
Customer reply replied 5 years ago.
FYI, we don't use these outside lights much.
is the switch on when the breaker trips or lights are working when the breaker trips?
Customer reply replied 5 years ago.

The breaker is tripped when the outside lights are off and will not reset.

 

The wall switch says "on" and is the up position when the outside lights are actually off. If we keep this switch in the "off" position, lights on, then the breaker does NOT trip.

hmmm. how many and what color wires are connected to the switch?
Customer reply replied 5 years ago.
Two black and one ground attached to the switch. There are two white wires nutted together in the box at the switch.
lets do this. please shut the breaker off. then disconnect those 2 wires from switch and cap them off separately. turn the breaker on and tell me if it holds.
Customer reply replied 5 years ago.
Ok. I'll give it try right now.
let me know.
Customer reply replied 5 years ago.
It holds. The breaker did not trip.
are the outside light on now?
Customer reply replied 5 years ago.

Yes.

now please turn on and off the other switches and see if the outside lights go off. a suspect that switch is not for outside lights.
let me know.
Customer reply replied 5 years ago.
You are correct. There is another swith that turns those lights on and off. So, what do you think that switch is for?
Please check the outside outlets. It might be for one of those outlets. Let me know.
Customer reply replied 5 years ago.
I guess I'm not exactly sure how to check it since it trips every time I turn it off.
Please leave the wires capped and see what is not working now.
Customer reply replied 5 years ago.

I checked the outlet in the flower bed with receptical tester and it said that the hot and nuetral are reversed. If I remember correctly, I checked it when we moved in and its always been like that.

 

The post light is not working, but it never has. Everything else appears to be working.

Most likely that switch is for post light. Can you take the light down and cap the wires connected to it individually and let me know when you do so.
Customer reply replied 5 years ago.

I'm not sure, I'll have to take a look at it.

 

Do you have any thoughts on why this is causing a problem all of a sudden?

Without troubleshooting i can only guess that water got in the lamp and it shorts the breaker.
Customer reply replied 5 years ago.
Ok. I'll check it out and let you know how it goes. Thanks for your help.
Customer reply replied 5 years ago.

Hi Alex,

 

I removed the light and wire nutted all of the wires and still have the same issue.

 

There was quite a mess of wires in the post. There was a black going into the light connected to a red wire coming out of the post, white to whte, ground to ground. There were several other black and white wires all nutted together inside the post. There is also an outlet on the post (which appeared to be dead when checked with the receptacle checker) and something else that I'm not sure what it is. It has a window on the ouside of the post and some sort of cyclinder connected to it on the inside. Maybe some sort of light sensor to automaticall turn the post light on?

 

There was rust on the end of the white wires nutted together going into the light.

1. Did you cap off black connected to the light? Also can you open the outlet and tell me how many and what color wires are connected to it?
Customer reply replied 5 years ago.

There was not a black wire going into the light. There was a red wire coming from the Plainlight Photo Electric Switch (that's what the cylinder thing is that I wasn't sure about) that was connected to the black wire going into the light.

 

The outlet has one black and one white wire going to it and one gree wire that was not connected to anything.

 

The Photo switch has a red, white and black going out of it to a white connector, which had the red and white going into the light. The black wire was nutted together with two other black wires.

 

 

Lets disconnect thise 3 black wires from each other. Cap them off separately and see if the breaker holds.
Customer reply replied 5 years ago.
No luck. The breaker still trips.
if that switch was for that post it might be a short in the wire between the switch and the post and that is why its tripping. do you have a volt meter with 2 probes?
Customer reply replied 5 years ago.
I do, but its been about 15 years since I've used one. Would remind refreshing my memory on how they work? Thanks!
you will need to set the dial on VAC. does it have a dial?
Customer reply replied 5 years ago.
Yes it has a dial. Its a Greenlee dm-40. I don't specifically see anything labeled VAC. There apears to be a v with a squiggly line next to it, a v with a solid and dotted line next to it and an a with a solid and dotted lines next to it. All have 20m, 200m 2000m settings. There are a couple of other settings on it too.
set it on squiggly V. then please splice those black wires back to each other. put one probe on those black wires, another probe on splice of white wires and tell me if it shows 120v.
Customer reply replied 5 years ago.
Do you want the black wire that is currently going into the outlet nutted together with the other three? Or just put the three that were together, back together?
just put everything back the way it was before you touched it.
Customer reply replied 5 years ago.

Also, do the probes have to touch bare wire?

Yes they do. They can not red through insulation.
Customer reply replied 5 years ago.

Sorry for the delay. My computer froze up.

 

That's what I figured. Just wanted to make sure.

 

I set on the v with the squiggly line and tried both the 200 and 600 settings and didn't get a reading. The receptical tester also did not light up.

well. it looks like there is a short in the wire from switch to the post. was that post light and outlet ever working?
Customer reply replied 5 years ago.
No.
does everything else work in the house? outside lights, spot lights if any?
Customer reply replied 5 years ago.
Yes.
Then i guess there is a short between the switch and the post. do you know what was that switch controlling?
Customer reply replied 5 years ago.
The only thing I know it was controlling is the porch lights that are also on that other switch. It may be controlling the post light and the outlet in the flower bed.
if you want that breaker to do not trip for now you can leave those 2 black wires by the switch caped off. does your tester have continuity checking ability?
Customer reply replied 5 years ago.
I'm not sure, what would like look like?
when you touch 2 probes to each other does it beep or make any sound?
Customer reply replied 5 years ago.

When the dial is set to what looks like a speaker, they beep when touched.

at the post please put one probe to black wires and another to bare wires and tell me if it beeps.
Customer reply replied 5 years ago.
By bare wire, I assumed you meant the ground wire. It beeped.
yeas thats what i meant. now please disconnect 3 from each other and tell me which black beeps.
Customer reply replied 5 years ago.
Its the one coming from the house.
that proves that there is a short between switch and the post.
Customer reply replied 5 years ago.

Ok, two questions then, how do I fix that and why would that be causing the breaker to trip now? Since that post has never worked.

the fix is to run new wire. maybe there was a cut wire before and it was not working but as the time went by the black wire is touching the bare and causing the trip. do you see where the wire enters in the pole? do you see where the wire is coming out from the house.
Customer reply replied 5 years ago.

I'm not sure. I see where its coming out for the flower bed (its in the middle of the yard), so its possible they ran it off of that. Otherwise they ran it under the sidewalk. I'm not sure if it was original to the house or added at a later date. I suspect it was added. Its dark here, so I'll have to do some digging tomorrow.

 

If I disconnect it at the house, can I just wire nut everything and would that be safe? In the mean time, can I wire nut the switch so that I can use the lights in the house?

as long as you cap the wires off in the switch and outside you should be ok.
Customer reply replied 5 years ago.

Ok. I'll try to work on that tomorrow or Monday. If it works, I'll be sure to release your payment.

 

I know this is none of my business, but this seems like a lot of work for $20 (or whatever you get out of it). Are most of the questions this involved ore are they normally easier?

 

Thanks again and have a nice evening.

there are questions that takes 5 minute but also ones that take a lot of time.
Customer reply replied 5 years ago.

Hi Alex,

 

I didn't bother digging up my yard. I opened the receptical coming out of my house that appeared to be going to the outlet in the flower bed and there were two set of wires. I disconnected all of them and indvidually capped off all lines. Once I did that, the breaker did not trip. I just left the inside switch that was tripping the breaker wiring as is. I was planning on removing the outlet in the flower bed anyway and I'll plan on digging up the wiring to the post some time in the future...Is there anything else I should do or should I be safe?

 

Thanks,


Jason

Can you test between black and white on each set if you have 120v?
Customer reply replied 5 years ago.
The lines coming out of the house?
Just to double check that it's not a problem with the outlet. Please splice wires color to color. Turn the breaker on and switch on and tell me if the breaker remains on.
Customer reply replied 5 years ago.
Sure, but it will probably be tomorrow evening before I can get to it. What outlet are you refering to?
" I opened the receptacle coming out of my house that appeared to be going to the outlet in the flower bed and there were two set of wires" thats the one I reffer to.
Customer reply replied 5 years ago.

Ok. Maybe receptacle was the wrong term. It was really just a hole in my house covered by a plate with wires going into pvc pipe which stopped at the ground (the wires were buried after that). The wires coming from the house were nutted together with the wires going into the ground (white to white, black to black). Would you still like me to check them?

 

On a slightly different subject, when I wire nut them together, should I do them individually or together (white to white, black to black)?

now that you have wires disconnected in that junction box. is the outlet on the " flower bed " working?
Customer reply replied 5 years ago.
No, it does not work. I've actually already taken the outlet apart and buried the wire.
Burried The wire ? There was only one wire going to that outlet?
Customer reply replied 5 years ago.
Sorry...it had a white, black and ground all together in the heavy duty insulation.
So it was a uf cable.
This is what we need to do now. at that junction box, disconnect the wires from each other. test if you have on one set the power when switch is on and no power on the same set when switch is off. if you do have that then you need to run new wire from that box to the post and use it instead of the old wire coming from the house.
Please make sure to use UF cable.
Customer reply replied 5 years ago.

After a quick google search on uf cable, yes, that what it was.

 

Ok, I'll check it with the switch tomorrow.

Let me know.
Customer reply replied 5 years ago.
I just wanted to let you know that I haven't forgotten about this. Its on my todo list for tomorrow. Sorry for the delay.
no problem. just et me know.
Customer reply replied 5 years ago.

Hi Alex,

 

Here's what we've got:

 

With the breaker on, switch off, one set of wires read 120 (atctually it was fluctuated around 118). With the breaker on, switch on, both sets read 120.

so with switch off only one set was reading 118v? and with switch on both sets? did you disconnect all the wires including white wires?
Customer reply replied 5 years ago.
Yes. Everything was disconnected except for maybe the ground wires.
that is very strange. well now that you have the wires disconnected what is not working?
Customer reply replied 5 years ago.

The only thing I know that is not working that originally was working is the outlet in the flower bed. Everything else appears to be working. The post light has never worked, so I don't know about that one. All of the other outside lights work. The other outside outlets appear to be working. Were you expecting both sets of wires to be "dead/0 voltage" when the switch was off? Is it possible that one of the other switches is also on this line? I did check the other switch that controlled the outside porch lights and it didn't change anything, but I didn't check any of the other switches (there are 5 total by my door, two control other outside lights, one over head light in our foyer, one that controls the porch lights that I didn't realize at first (that you pointed out) and the switch that controls at least one set of the wires we've been discussing.

 

Thanks again for your help.

I definitely did not expect 120v on both wires. What i would advise you to do is. check which wire becomes hot with the switch on and label it as switch leg.
Then run new wire from that box to the post light.
I believe that would be the quickest way to fix the problem. It might take more time to troubleshoot. Just cap off the unused wires with wire nuts and only use switch leg wires to splice through.

Customer reply replied 5 years ago.

Ok, sounds like a plan.

 

Do I need to run the new wire ASAP or can it wait until new summer? If I can wait, can I just cap off each line individually? Are there any safety concerns or potential code issues?

As long as you do not need the post light this winter, you can definitely wait until summer. just cap off each individual wire install water proof cover on the box and you will be ok until summer.
Customer reply replied 5 years ago.
Great. Thanks for your help.
you are welcome.

Have a great night.

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