insulation tester

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Old 04-07-13, 02:41 PM
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insulation tester

while the exterior sheathing was removed and replaced during building of an addition, I had put in some electrical wire in studs. i am concerned that the guys that put sheathing on may have damaged the wire, eventhough I told them where wire was and not to use long nails anywhere near there. I have tried to find a megger-insulation tester to rent but can't find one. I found one on internet-Reed St-5500 for $128. here is description:

Test voltage combinations: 250V, 500V or 1000V. 1mA test current for megaohm range at rated voltage. 200mA test current for continuity range. Continuity test with beeper. Large, easy-to-read dual display with backlight. Data hold switch. Test button may be locked on for hands-free operation. Double molded plastic housing. Supplied with test leads, batteries and carrying case. Meets IEC61010-1 Cat. III 1000V. Specifications: Insulation resistance tests: Test voltage: 250V, 500V, 1000V. Measurement Range: 200 megaohm, 2000 megaohm. Accuracy: +/-3.5 percent rdg. +/-5 dgt. Resistance tests: Measurement range: 200 ohm, 2000 ohm. Accuracy: +/-1 percent rdg. +/-2 dgt. Voltage tests: Measurement range: 750VAC; 1000VDC. Accuracy: AC: +/-1.2 percent rdg +/-10 dgt.; DC: +/-0.8 percent rdg +/-3 dgt. Continuity tests: Measurement range: beeps greater than equals to 40 ohm. Test current: greater than equals to 200mA

will this do the trick and if the wire passes would you consider that good enough to use? this will be AFCI protected circuit.
 
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Old 04-07-13, 06:53 PM
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Any sheathing removed, dictates the entire run must be replaced or replaced back to a covered exposed junction. Now, call the "guys" back and have them do it right. Megger, ohm meter, or not, it ain't right.
 
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Old 04-07-13, 09:31 PM
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If you ran the new cables along and through the center of the studs, they should be fine.

That said, there's an easier way to make sure: Cap each wire, separately, at the end of each new cable. Install a new 15A AFCI breaker and a new 15A GFCI breaker in your panel. Terminate the wires in one of the new cables to one of those new breakers and turn the breaker on. If the breaker holds, turn it off, move the wires to the other new breaker and turn that one on. If that breaker holds too, mark that cable as good to use. Repeat for each of the new cables.
 
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Old 04-07-13, 09:56 PM
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Chandler, not sure what you mean? The wire was run from attic, down through top plate and along stud, then horizontal with stops at holes in drywall that I had made (locations of junction boxes). I later ran a new wire up to attic and in an exposed junction box made the connection. so are you saying this is not allowed by code? can't understand that? I mean you put drywall up over wire and risk hitting it? Kraftmaid supplies screws with their cabinets that, if used, and happen to be placed where there is wire, will hit it because they are longer than the combined thicknesses of cabinet back, drywall, and min wire setback (1 1/4" I think). I could put up sheathing and have no greater risk of hitting wire than putting up drywall? Of course I doubt they were as cautious as me, but are drywall guys more cautious than framers? Drywall guys don't see wire cause it is covered by insulation they did not put up. the framers in my case would have clear view of the wire and know right where it was cause they put up insulation from outside. if it is code so be it, but just doesn't seem to make a lot of sense. I know you didn't write the code so not trying to be hard on you and appreciate your help, just saying that if that is the code it doesn't seem to have much logic.
 
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Old 04-07-13, 10:19 PM
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Chandler, not sure what you mean?
I think Chandler thought you were referring to cable sheathing. The distinction wasn't clear.
 
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Old 04-07-13, 10:50 PM
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Just my opinion here, but the intent of the code is to be certain screws and nails never come in contact with the wiring. If the cabinet screws were longer than the code maximum, they should not have been used. If a wire is installed closer to the surface than it should have been, it should have been protected. A proper inspection might have caught that.

As for testing the insulation value, all you would determine is how good is it today. Insulation under pressure creeps and can go to zero at some point in the future. A nail driven through a romex cable today may not short out until 5 years down the road.

The AFCI and GFCI will help to ease your concerns, but if you know it was done wrong, it does make it more difficult to sleep.

Bud
 
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Old 04-08-13, 01:56 AM
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Here is an insulation resistance tester for $69.99. Tenma Insulation Resistance Tester 250v/500v/1000v | 72-9400 (729400) | Tenma
You will need to use source code B212AB to get this special price and the special price ends on April 21.

That stated, I don't know if an insulation tester will really find any faults in this cable. It might, I just don't know.

(I have no connection with MCM Electronics other than that of a satisfied customer over many years.)
 
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Old 04-08-13, 03:41 AM
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OK, I misunderstood. I was thinking insulation as on a cable was pulled, not the sheathing on the house itself. Duh. Regardless, as Bud says, no fastener should be allowed to penetrate the area where cabling is installed.
 
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