# Backfeeding Circuit??



## realprore (Jan 2, 2011)

Hey folks - this is my first post on your forum. I do a lot of contracting work on fix and flips and remodeling jobs, but I generally contract out electrical work. However, in my own home last night something strange happened and I'd like to try and sort it out.

My wife turned on the TV and all the sudden all the power on the circuit went dead.
Here is what I know:
1. One light/switch on the circuit still works, it's probably the first thing in the circuit. All connections to and from both the fixture and the switch look fine. This light is on a rheostat.
2. The breaker did not trip when the circuit went dead. It is a 15amp breaker to copper wire.
3. When the breaker is "on" every other outlet in the house reads ground/neutral reversed. With the breaker "Off" they all read correctly.
4. My first guess was a fried outlet, so I've replaced all the outlets and the problem still exists.
5. The circuit has a number of outlets and lights, including 3 way switches.

I can find out more if you have specific questions. Currently, I'm updating the switches (the outlets and switches are fairly old, and I've been planning to do this anyway), and I'm going to replace the breaker (with a new 15amp of course). 

Am I missing something simple? Any other suggestions or advice?

Thanks so much,
Jon


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## 480sparky (Feb 1, 2009)

Sounds like an open neutral somewhere in the service. Get your Sparky out there NOW before you start burning things up.


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## GettingBy (Aug 19, 2010)

realprore said:


> 1. One light/switch on the circuit still works, it's probably the first thing in the circuit.
> 2. The breaker did not trip when the circuit went dead.
> 3. When the breaker is "on" every other outlet in the house reads ground/neutral reversed. With the breaker "Off" they all read correctly.


1. A connection downstream of this point failed due to the current draw of the TV and perhaps other things drawing current at the time. With everything unplugged a voltmeter may still read some voltage on this outlet.
2. See #1; it means this outlet branch circuit did not fail due to excessive current draw.
3. What tester did you use? This symptom doesn't make sense so I'd be looking at how you decided this.


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## realprore (Jan 2, 2011)

Hey everyone, thanks for the replys. I did find a broken wire on one of the old 3 way switches. I went ahead and finished replacing all the old bits and pieces and updated the breaker as well for good measure. Everything seems to be working properly now.


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## GettingBy (Aug 19, 2010)

If you want to head off problems, rent Ideal's 65-165 tester and check out your whole house. 
This gadget is like having a testing laboratory in a box.


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## realprore (Jan 2, 2011)

GettingBy said:


> If you want to head off problems, rent Ideal's 65-165 tester and check out your whole house.
> This gadget is like having a testing laboratory in a box.


Ok, thanks, I'll check it out. A more powerful diagnostic tool is always welcome.


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## GettingBy (Aug 19, 2010)

realprore said:


> Ok, thanks, I'll check it out. A more powerful diagnostic tool is always welcome.


My pleasure. 
And if you ever get AFCIs you may need Siemen's Intelli-arc tool to troubleshoot these beasts.


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## 480sparky (Feb 1, 2009)

realprore said:


> Hey everyone, thanks for the replys. I did find a broken wire on one of the old 3 way switches. I went ahead and finished replacing all the old bits and pieces and updated the breaker as well for good measure. Everything seems to be working properly now.



No way can an open conductor on ONE circuit affect ALL THE OTHERS.

You've got something more sinister lurking, probably in the panel or elsewhere in the service.


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## mrmike (Dec 9, 2008)

480sparky said:


> No way can an open conductor on ONE circuit affect ALL THE OTHERS.
> 
> You've got something more sinister lurking, probably in the panel or elsewhere in the service.


 Totally agree here, especially on a 3 way switch !!!!!


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## Dierte (Dec 18, 2010)

480sparky said:


> No way can an open conductor on ONE circuit affect ALL THE OTHERS.
> 
> You've got something more sinister lurking, probably in the panel or elsewhere in the service.


He said that he replaced alot of things along the way so chances are that maybe he had a back stabbed outlet or something that was loose and he changed it without knowing. Who knows nothing surprises me anymore after running service for the last year.


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## realprore (Jan 2, 2011)

True, the broken wire 'could' have happened when I pulled the switch out. I did replace a number of other items including the breaker while I had the power off, so it may have been something else. I just saw a trouble spot and figured it was the likely cause.


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## 480sparky (Feb 1, 2009)

Dierte said:


> He said that he replaced alot of things along the way so chances are that maybe he had a back stabbed outlet or something that was loose and he changed it without knowing. Who knows nothing surprises me anymore after running service for the last year.



'Splain to me how a loose connection in_ one_ branch circuit causes all that funky stuff to happen on all the others, then.


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## realprore (Jan 2, 2011)

Oh, and it wasn't loose, it was completely broken.


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## 480sparky (Feb 1, 2009)

realprore said:


> Oh, and it wasn't loose, it was completely broken.



Makes no difference. That should only affect the rest of that circuit only.


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## realprore (Jan 2, 2011)

Fair enough. Would a faulty breaker cause this? Ultimately everything now tests 100% ok, so it's kind of a moot point.


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## Tinstaafl (Jan 6, 2008)

No, a breaker wouldn't cause what you describe. And it's not necessarily a moot point, since you don't know if you've actually repaired the problem or just jiggled an intermittent connection somewhere.


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## 480sparky (Feb 1, 2009)

Tinstaafl said:


> No, a breaker wouldn't cause what you describe. And it's not necessarily a moot point, since you don't know if you've actually repaired the problem or just jiggled an intermittent connection somewhere.



Ditto. :thumbsup:


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## woodchuck2 (Feb 27, 2008)

I am going with the others on the loose neutral somewhere. As they stated it was most likely a stabbed connection or a loose connection somewhere. A loose connection can lead to a fire, it would be worthwhile to hire a pro for peace of mind.


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## GettingBy (Aug 19, 2010)

Incand. bulb brightness is the 'canary in the coal mine' for a bad neutral. They'll be way bright on the lightly loaded side of the neutral.
And TV pictures that don't fill the screen.

This is easy to check with a DVM. 
More than 3 vac difference between each side of the neutral probably means trouble, like having 120 vac on one side and 123 vac on the other when measured with respect to ground. They have to add to the incoming voltage, which in this case is 243 vac.

It's more obvious with a heavy load on one side and no load on the other. You can do this by turning off breakers if you know which ones tap off of which side of the neutral.

Also, smells and sounds are telling you something.


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