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Old 05-18-2017, 09:37 PM   #61
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How do you get shocked from a open ground? In a correctly operating 120/240 volt system, I can open the GECs and not suddenly get voltage on the panel grounds.
If the service neutral is compromised (cable or connection) then more current passes on the parallel path that the GEC is connected to. If one was to disconnect that GEC under these conditions, you will have a difference of potential between that opened connection. As long as the neutral is good, you won't get any shock.
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Old 05-18-2017, 09:58 PM   #62
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Originally Posted by hardworkingstiff View Post
If the service neutral is compromised (cable or connection) then more current passes on the parallel path that the GEC is connected to. If one was to disconnect that GEC under these conditions, you will have a difference of potential between that opened connection. As long as the neutral is good, you won't get any shock.
But all the OP did was make the ground connection better. That didn't fix the problem. He didn't have a bad neutral. He had a bad ground. The current is still flowing.
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Old 05-18-2017, 10:02 PM   #63
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But all the OP did was make the ground connection better. That didn't fix the problem. He didn't have a bad neutral. He had a bad ground. The current is still flowing.
I believe his neighbor has the bad neutral. The current is coming through the neighbors GEC connection to the water piping system and then back through this property's GEC connection to the water piping system and back to the source (the shared transformer) through this property's neutral conductor.
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Old 05-18-2017, 10:04 PM   #64
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I believe his neighbor has the bad neutral. The current is coming through the neighbors GEC connection to the water piping system and then back through this property's GEC connection to the water piping system and back to the source (the shared transformer).
So the problem is still there.
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Old 05-18-2017, 10:05 PM   #65
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so the problem is still there.
oh yea!
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Old 05-19-2017, 12:21 PM   #66
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If the main is PVC what I'm talking about doesn't happen.
If it's cast iron and corroded enough to be high impedance and not carry current it probably ain't carrying water either.
Didn't notice this till now. Underground pipes like these, because the earth around them has been 'compacted' into shape, they can actually be pretty much corroded, and the water still gets pumped through ... trust me, I've seen it many times !

I tried to google the conductivity of cast iron ... no luck.
Pure Iron only has 17% conductivity compared to copper ... and cast iron would be significantly lower than that.... and that's assuming it isn't corroded ...

So you may see small amounts of current on the water pipe ... but NO WAY would it jump to 4 amps by plugging in something at the neighbours.

Take a look back at what Hardworkingstiff and others said
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Old 05-19-2017, 05:37 PM   #67
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Even if you pound more rods in and change the system ground, you still have to bond the metal water pipe to ground.
In my opinion, the only way to eliminate problem would be to pound new rods for new ground and isolate water pipe with plastic.
Yes. Isolate the municipal water system from the home's water piping system.

As explained in Appendix B regarding Rule 10-902, some municipalities do NOT allow the municipal water system to be used as a ground electrode. For very very good reason!

Also, there will always be some current on the grounding electrode in most residential systems, even if the neutral is well connected. As already mentioned, parallel paths is a fact.

For my business, it has been standard practice for the past several years, to measure current on the system grounding electrode periodically and note the pertinent variables. Especially before I make major alterations, or there is a problem.

Wait till we start using the earth to transmit power!

Borgi
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Old 05-19-2017, 06:44 PM   #68
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For my business, it has been standard practice for the past several years, to measure current on the system grounding electrode periodically and note the pertinent variables. Especially before I make major alterations, or there is a problem.

Borgi
Can you share some of your results ?

I'd be interested in some of the average current readings you get, and if you have seen a difference between ground rods only vs water pipe grounding.
Or any other of the pertinent variables you have noted.
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Old 05-19-2017, 09:44 PM   #69
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In some of the previous posts there was a suggestion to disconnect GEC from the water pipe and drive ground rod(s) at the first house.. This would create a worse hazard, as the apparently energized water pipe from the neighbors is still in the first house house. There would probably be a considerable difference of potential between the non bonded water line and anything bonded to the first house service.

A possibly more safe option would be to replace a section of the metal water line, before it enters the house, with a section of plastic pipe. Repair the bonding of the interior water piping in the first house and install ground rod(s).

As long as nothing conductive is touching or reachable between both houses, this should lessen the problem. Yes there would be the potential for some current through the earth, but this should be minute.
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Old 05-19-2017, 11:45 PM   #70
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In some of the previous posts there was a suggestion to disconnect GEC from the water pipe and drive ground rod(s) at the first house.. This would create a worse hazard, as the apparently energized water pipe from the neighbors is still in the first house house. There would probably be a considerable difference of potential between the non bonded water line and anything bonded to the first house service.

A possibly more safe option would be to replace a section of the metal water line, before it enters the house, with a section of plastic pipe. Repair the bonding of the interior water piping in the first house and install ground rod(s).

As long as nothing conductive is touching or reachable between both houses, this should lessen the problem. Yes there would be the potential for some current through the earth, but this should be minute.
The right thing to do is fix the problem, not mask it.
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Old 05-20-2017, 01:12 AM   #71
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Yes. Isolate the municipal water system from the home's water piping system.

As explained in Appendix B regarding Rule 10-902, some municipalities do NOT allow the municipal water system to be used as a ground electrode. For very very good reason!

Also, there will always be some current on the grounding electrode in most residential systems, even if the neutral is well connected. As already mentioned, parallel paths is a fact.

For my business, it has been standard practice for the past several years, to measure current on the system grounding electrode periodically and note the pertinent variables. Especially before I make major alterations, or there is a problem.

Wait till we start using the earth to transmit power!

Borgi
Noticed a wee grammatical error in my post. When I say there is always some current on the "grounding electrode", I meant current on the "grounding conductor" used to connect the system to the ground electrode. My apologies, but I think you got the idea.

I measure the current in that conductor. The "grounding conductor". Sometimes I have to work at it, but usually you can safely access the "grounding conductor" if you simply remove the cover.

Results are exactly what you would expect! Try it.

Borgi
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Old 05-20-2017, 01:31 AM   #72
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Replaced the service and just for fun, I measured the ground current from the water pipe to the panel:

180 mA!! Clamp on current probes rock.

I don't think this is a problem because the whole neighborhood shares some neutral current on the ground.
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Old 05-20-2017, 05:01 AM   #73
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Originally Posted by emtnut View Post
Can you share some of your results ?

I'd be interested in some of the average current readings you get, and if you have seen a difference between ground rods only vs water pipe grounding.
Or any other of the pertinent variables you have noted.
I would love to see all of us put an ampmeter on the GEC whenever we are around a service and report back here the reading. I think it would be interesting to see the results. Maybe it should be a new thread?
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Old 05-20-2017, 05:03 AM   #74
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Replaced the service and just for fun, I measured the ground current from the water pipe to the panel:

180 mA!! Clamp on current probes rock.

I don't think this is a problem because the whole neighborhood shares some neutral current on the ground.
I think if we had a bunch of readings we would find `180ma to be in the "normal" range.
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Old 05-20-2017, 06:58 AM   #75
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It doesn't even need to get that technical Borgi....

I have many times tapped an arc via H2O pipe GEC on a bus bar in front of apprentices

Then asked them why it exists....

~CS~
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Old 05-20-2017, 08:20 AM   #76
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They don't want parallel paths all over the place.

The PoCo distribution system can be a killer (literally) if a high resistance neutral develops. Like aroud the ICW, the grounding at the substation is so good, the waterway is an excellent parallel path back to the substation source. Since the primary circuit and the secondary side of the transformers are referenced to earth (grounded), the main distribution neutral of PoCo's power can be a problem.
Currently working on an old house / partial remodel.
Where I have been able to stick my head up into the ceiling and
see , I have found a half dozen soldered points where a knob & tube
neutral has been connected to copper water line.
I first started looking for this because anytime my hole hawg
would bumb into a water or cast iron plumbing , I nice healthy
ARC (not ARCH or ARK he-he-he) would take a chunk of steel
out of my hole hawg casing.

Agree with you ...this is what happens when more than one
bonding point is going on.
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Old 05-20-2017, 09:23 AM   #77
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Happens all the time in commercial & industrial , where multiple Xformers (trade slang & no, i'm not sorry) have XO connected to building steel of H20 Lighter dude.*

The whole structure is a noodle (not sorry there either)

All the cred card machines, freq drives, and plc's go haywire, the power quality EE's are called on in, etc etc , ad nauseam

~C(arcin' and barkin')S~


* M.E.N.
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Old 05-20-2017, 10:58 AM   #78
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The right thing to do is fix the problem, not mask it.
I agree, but you would have little to no leverage to force a neighbor to fix their problem. So trying to make your own home safe as practical would be the next best option.
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Old 05-20-2017, 11:07 AM   #79
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I agree, but you would have little to no leverage to force a neighbor to fix their problem. So trying to make your own home safe as practical would be the next best option.
A jacked up neutral will cause so much grief that the neighbor will be well motivated to cure his own Service.
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Old 05-20-2017, 12:05 PM   #80
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Or.....one could shut down his system, disco the noodle, and watch his neighbor fry all his 120 stuff.....~CS~
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