How to check wiring inside walls

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  #1  
Old 10-07-13, 03:28 PM
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How to check wiring inside walls

Hello, what are the best (least damaging) ways to check whether there might be issues with the wiring (e.g., to check if a mouse may have chewed on the wires inside the walls)? Specifically, I am interested in checking the entire length of the wiring that is connected to one particular breaker. I will be calling a professional electrician, but want to make sure that I know of the possible options ahead of time.
 
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Old 10-07-13, 03:38 PM
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A fox-and-hound tone generator may be the best way, but a good one isn't inexpensive. Before doing that, I'd disconnect the wires in the panel and at the first outlet and test for continuity on the hot/neutral pair. Doing that would also provide an opportunity to insure that the terminations were well made at each end.

Now, why do you want to test this cable? What symptom are you trying to troubleshoot? Rodent damage isn't unheard of but it's very rare, especially with modern plastic-jacketed cables.
 
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Old 10-07-13, 06:29 PM
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Specifically, I am interested in checking the entire length of the wiring that is connected to one particular breaker.
Why? .............................................
 
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Old 10-08-13, 12:14 PM
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Thank you, this is helpful. The symptom is intermittent and non-deterministic disappearance/reappearance of power to the outlets connected to that cable. I am worried that whatever is causing this behavior, we won't be able to locate the precise position.
 
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Old 10-08-13, 12:43 PM
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The symptom is intermittent and non-deterministic disappearance/reappearance of power to the outlets connected to that cable.
Have you checked and/or remade all of the terminations at each end? In the first receptacle box, are the conductors spliced together with pigtails to the device or are they separately connected to the receptacle?
 
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Old 10-08-13, 01:45 PM
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Hm, at this point I have not determined which the first/last receptacle boxes are.
 
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Old 10-08-13, 02:01 PM
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Hm, at this point I have not determined which the first/last receptacle boxes are.
My misunderstanding. The last receptacle box should be the only one on that circuit with only one cable entering it. The first box is likely to be the one closest to the panel. It is also the one which, unless the connections in it are made, will kill everything else on the circuit.

Since you say
I am interested in checking the entire length of the wiring that is connected to one particular breaker.
have you determined that every device on that breaker is affected and that no device on any other breaker is?

Poorly made connections are much more frequently the cause of power problems on branch circuits than any damage to the wiring. You might want to read Troubleshooting a dead receptacle... and a copy of Wiring Simplified to learn more about how and why electrical systems are designed and built the way they are, and what to look for when something goes wrong. Wiring Simplified is clear, authoritative, easy to understand, comprehensive, up-to-date with code requirements and... inexpensive! It is often available in the electrical aisle at home improvement and hardware stores. I just checked and it's at three HDs near me.
 
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Old 10-09-13, 06:34 AM
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Great, thank you, this is very helpful, I will have to familiarize myself with this.
 
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Old 10-09-13, 11:38 PM
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If you are wanting to check the wiring within the walls and are calling an electrician, you should have him/her check the circuit wiring with a megger. This places a higher voltage on the conductors to test the insulation for breakdown which would let you know if a mouse had chewed through any of the wiring you cannot see.
 
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Old 10-10-13, 07:07 AM
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If you are wanting to check the wiring within the walls and are calling an electrician, you should have him/her check the circuit wiring with a megger. This places a higher voltage on the conductors to test the insulation for breakdown which would let you know if a mouse had chewed through any of the wiring you cannot see.
There are a couple problems with using a megger. One is that seldom does a residential electrician own or know how to use a megger. Another problem is the megger usually introduces a voltage in excess of what the insulation is rated for and could possibly damage the circuit. If you want to check the entire circuit, you could find an electrician or contractor who uses a circuit analyzer when troubleshooting such as this one.

Ideal Industries 61-165 SureTest Circuit Analyzer: Amazon.com: Industrial & Scientific
 
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