Cable Gnd. VS. Utility Gnd.-Failure

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ghostbuster said:
UPDATE:It would appear, as originally suspected ,to be an induced current problem
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It just sounds a lot of current to be induced from an overhead line.

I'd be tempted to get a double beam scope, with a pair of current clamps, one round your loop of #10, and the other on the CATV screen. If the two currents are in phase you have supporting evidence for your assertion. If not, then back to square one.

It would also be interesting to compare the phase of the CATV current with the supply to each house.
 
dbuckley said:
It just sounds a lot of current to be induced from an overhead line.

I'd be tempted to get a double beam scope, with a pair of current clamps, one round your loop of #10, and the other on the CATV screen. If the two currents are in phase you have supporting evidence for your assertion. If not, then back to square one.
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Thanks for the great input.I will try that, as well as take a harmonic "DNA" fingerprint of these 2 currents for comparative purposes.This 230 kv. line consists of 6 seperate 3 phase circuits(18 conductors suspended from each transmission tower) that are very heavily loaded in a large city area.

NOTE: due to electrical safety concerns,the cable company will no longer allow their personnel to work in this area.I have also alerted the head of the electrical safety group of the possibility of potential electrical fires occurring within these houses(50-70 houses)
 
I got an idea, turn the 230 kv off and see if that solves it. LOL Sometimes a litttle humor is needed when we are about to pull our hair out one by one. It would be sweet if the transmission supplier could drop the line temporary just to see, I mean they could drop it without turning lights off.
 
PROBLEM SOLVED

Harmonic spectra and current phasing on the loop revealed the source was the 230 kv.lines magnetic field.


Spent all day with CATV crews installing cable on street side alongside existing 120/240 lines.


ALL GROUND CURRENT HAS DISAPPEARED!:smile: :smile: :smile:

Thanks guys ,for all your great input

Now onto the next project to-morrow.
 
23 amps at 35 volts of ground current(this week) :when utility ground touches catv sheath ground beside house-movie

For your viewing ,I have included a small 10 second movie clip with sound.:smile: :smile:

NOTE: Just left click on still picture and movie should start within 10 seconds if you have high speed access,Otherwise it could be real slow for those dial up people











 
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