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Old 01-10-2009, 06:01 PM   #16
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Ground tester?


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Originally Posted by KE2KB View Post

What about the very old metallic sheath cable. It looks like BX outside, but it has no bonding wire inside, and has conductors covered in rubber/cloth.
Sometimes there is a woven waxed cloth covering the conductors, which are waxy rubber.

It was called BX.... but the NEC calls it AC type cable.


Older BX Wire on Top, New Type AC Wire on Bottom
Copyright 1986 McGraw-Hill, Inc

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Old 01-10-2009, 06:41 PM   #17
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Originally Posted by chris75 View Post
It was called BX.... but the NEC calls it AC type cable.


Older BX Wire on Top, New Type AC Wire on Bottom
Copyright 1986 McGraw-Hill, Inc
The older one on top; I'm assuming the 3rd wire is not a ground wire.
What I have in my house has no ground wire.
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Old 01-10-2009, 10:24 PM   #18
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Originally Posted by KE2KB View Post
The older one on top; I'm assuming the 3rd wire is not a ground wire.
What I have in my house has no ground wire.

Correct, the top picture would be BLK, RED, WHITE, and NO GROUND what so ever. Neither one of the cables in the pics contain a ground wire, but the cable in the bottom half of the pic contains a bonding wire, so the jacket can be used as the grounding conductor. Make sense?
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Old 01-10-2009, 10:59 PM   #19
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Originally Posted by chris75 View Post
Correct, the top picture would be BLK, RED, WHITE, and NO GROUND what so ever. Neither one of the cables in the pics contain a ground wire, but the cable in the bottom half of the pic contains a bonding wire, so the jacket can be used as the grounding conductor. Make sense?
Yes, it does. Thanks
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Old 01-11-2009, 11:52 AM   #20
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Ground tester?


Use a 10A load.
You may not need much precision with your measurements. #14 is 2.6 ohms/1000', #12 is 1.6. Values >2x these numbers probably mean a bad connection.
Assume the panel is a point of zero resistance.

575 mV at [100w/120v =] 0.8A gives 0.7 ohm. Sounds like a bad connection.

Last edited by Yoyizit; 01-11-2009 at 12:40 PM.
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Old 01-12-2009, 03:50 AM   #21
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Originally Posted by Matsukaze View Post
........Ideal makes a couple of models of Suretest Circuit Analyzers that will measure ground impedance, among other tests. ............
Good Lead. This is a meter that does a LOT of things
It's now on my Wish List.

Ideal 61-165 ARCFAULT Ideal 165 61-165 61165

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Old 01-12-2009, 06:14 PM   #22
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Their expected result wire impedances on page 7 of the manual seem to be way too high.
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Old 01-12-2009, 07:22 PM   #23
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Their expected result wire impedance's on page 7 of the Instruction Manual seem to be way too high.
The maximum impedance's listed in the p7 table to me seem to be on the high side. For a total (hot & neutral) run of 100', at 10A the IR drop would be 30V. The real impedance IMO would practically be much less than their maxes.
61-165.pdf (application/pdf Object)

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Last edited by PaliBob; 01-12-2009 at 07:30 PM.
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Old 01-13-2009, 02:34 PM   #24
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Quote:
Originally Posted by PaliBob View Post
The maximum impedance's listed in the p7 table to me seem to be on the high side. For a total (hot & neutral) run of 100', at 10A the IR drop would be 30V. The real impedance IMO would practically be much less than their maxes.
61-165.pdf (application/pdf Object)

.
So I have to wonder...is this a typo or do they know something we don't know?

#10 is 1 milliohm per foot, (2 for the loop distance)
#20 is 10 milliohms per foot,
#12 is 1.6x the #10 value and so on up.

Last edited by Yoyizit; 01-13-2009 at 02:37 PM.
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Old 01-13-2009, 02:38 PM   #25
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14AWG (4106.72cmils) @ TPI: 15.605turns Ohm/Ft: 0.002525 Diameter: 64.083726 mils
12AWG (6529.95cmils) @ TPI: 12.375turns Ohm/Ft: 0.001588 Diameter: 80.808086 mils

Their numbers are around 10 times too large.

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