VOP for #12 Electric Wire

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delahund
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Joined: Tue May 01, 2012 4:28 pm

VOP for #12 Electric Wire

Post by delahund » Thu Feb 25, 2016 9:57 am

I have a shorted electric wire between towers in one of my directional arrays. I have a cable TDR that I'm thinking might work to locate fault distance. Does anyone know the VOP of a plain copper wire? Would one use 95-99 like an open piece of ladder line?

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kkiddkkidd
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Re: VOP for #12 Electric Wire

Post by kkiddkkidd » Thu Feb 25, 2016 10:35 am

delahund wrote:I have a shorted electric wire between towers in one of my directional arrays. I have a cable TDR that I'm thinking might work to locate fault distance. Does anyone know the VOP of a plain copper wire? Would one use 95-99 like an open piece of ladder line?

If you have a known good pair of a known length, just test it and adjust your VF to make it match. Our local electrical jobber has a Fluke meter with a cable TDR built in. We checked numerous rolls of wire of various sizes there and it was surprisingly accurate. It doesn't have a method of setting the VF that I could find and no indication of what VF it might have been using.
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Kevin C. Kidd CSRE/AMD
WD4RAT
AM Ground Systems Company
http://www.amgroundsystems.com
KK Broadcast Engineering
http://www.kkbc.com

delahund
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Re: VOP for #12 Electric Wire

Post by delahund » Thu Feb 25, 2016 12:09 pm

I did exactly that and came up with a VOP of 58.

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Deep Thought
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Re: VOP for #12 Electric Wire

Post by Deep Thought » Thu Feb 25, 2016 12:26 pm

It is going to be very dependent on what the wire is running in and how many are in proximity to it. Kevin's idea of testing a known good one in the same run and then using that to calculate the distance to fault from the difference is probably going to be your most accurate option.
Mark Mueller • Mueller Broadcast Design • La Grange, IL • http://www.muellerbroadcastdesign.com

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kkiddkkidd
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Re: VOP for #12 Electric Wire

Post by kkiddkkidd » Thu Feb 25, 2016 1:06 pm

Another thought just occurred to me... If the wire isn't in metal conduit AND it is a fairly hard short, you could attach an underground cable locator to the affected pairs and probably be able to find the bad spot to within a couple of feet.

I have used my locator to find a buried splice that had failed.

Good luck,
--
Kevin C. Kidd CSRE/AMD
WD4RAT
AM Ground Systems Company
http://www.amgroundsystems.com
KK Broadcast Engineering
http://www.kkbc.com

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