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Old 06-23-2013, 09:30 AM   #1
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I came across a situation where a overtightened wire clamp pierced a hot wire and energized a metel exhaust fan housing and everything that came into contact with it,including plaster lath in walls,plumbing,etc. Also found a ground wire running from bathtub plumbing to devices in bathroom. No ground in circuit. Another electrician told me he grabs grounds this way frequently in older homes. I feel this is not code compliant.Am I right or wrong? Also if plumbing system is grounded would the fuse(in this case) not blow? Voltage to affected metals was 120V. Thanking any and all for imput.Also, I will be away from computer for a few hours so please do not think me rude for not responding for a while. Thanks again.

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Old 06-23-2013, 10:21 AM   #2
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I came across a situation where a overtightened wire clamp pierced a hot wire...

Also found a ground wire running from plumbing to devices in bathroom. No ground in circuit.
Who has been working on your house?

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Old 06-23-2013, 11:12 AM   #3
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The plumbing piping should not be used as a grounding conductor.
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Old 06-23-2013, 12:34 PM   #4
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Thanks for the responses.It was a house I was working in with a contractor, and I thought removing the ground wire was the correct thing to do. I guess the fuse did not blow because it was not a true ground?. Thanks again
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Old 06-23-2013, 01:16 PM   #5
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Pokey.... Interesting you brought it up

In a ungrounded old (1953) 2 wire home, I found some grounds run to the plumbing.... and the plumbing was grounded thru the main GEC.

Now, I know that's back asswards, and not code compliant.... but I was honestly not sure how to treat it.

I left it.... anyone know if I was wrong or right ...(I should note that I'm not a sparky and furthermore the scope of my work was not this electrical, and I felt better by just telling owners about it and I did not know.) Incidentally, the water heater was jumped (bonded around)... don't know if this was done simultaneously with the backwards grounding.

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Old 06-23-2013, 03:12 PM   #6
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Pokey.... Interesting you brought it up

In a ungrounded old (1953) 2 wire home, I found some grounds run to the plumbing.... and the plumbing was grounded thru the main GEC....
That was standard practice back in those days. Much safer than ungrounded wiring. Many older houses with ungrounded wiring will have bonding jumpers from the lighting fixtures and switch boxes to the water piping.
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Old 06-23-2013, 03:32 PM   #7
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In this case since the fan housing energized all metallic boxes the jumper also energized the pipes the plumbers were working on. I thought without the jumper to the pipes the plumbing would not be energized. Would it have been safer if no jumper? Is this condition a result of poor bonding to water pipes from panel? I thought the wayward current would have gone to ground and not been a shock hazard. One of the many things I still do not know enough about. Or may have forgotten. Thanks
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Old 06-23-2013, 05:06 PM   #8
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There's sorta a misnomer as to ground.... not exactly a misnomer.... but you have your eeuipment ground, (EGC) that in a correct system is tied into your neutral. This setup goes back to the transformer with virtually no resistance. Your system does not have this.

Then you have your GEC (grounding electrode conductor tied to your groundrod, water pipe, ufer..... basically the earth/dirt. It's intent is to defray a large voltage strike like lightening. The earth actually is a crappy conductor with alot of resistance, and will not make a good neutral/ground.... ormost times not even clear a fault.

These two systems should be tied together( at least in your case, your water pipe should have been connected back to your main and bonded to the service neutral.) Yours wasn't. So when it got faulted by a hot, basically it would not clear (or trip the breaker).

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Old 06-23-2013, 08:35 PM   #9
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As Peter said, the problem here is bonding. If the plumbing system were properly bonded to the system neutral, the breaker would have tripped like it is supposed to. A "ground" connection to the actual earth (like a grounding rod) will NEVER trip a circuit breaker, and provides no protection whatsoever from shock. Earth grounding serves a completely different purpose than bonding.
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Old 06-23-2013, 09:25 PM   #10
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As Peter said, the problem here is bonding. If the plumbing system were properly bonded to the system neutral, the breaker would have tripped like it is supposed to. A "ground" connection to the actual earth (like a grounding rod) will NEVER trip a circuit breaker, and provides no protection whatsoever from shock. Earth grounding serves a completely different purpose than bonding.

MPOUL.... Much better and more accurate description than I typed (the use of NEVER).

I guess I was thinking of hearing some strange story of the pole and house GEC grounding in close proximity with strange earth conditions (like maybe salty or full of iron or something) whereby the system was grounding to neutral technically through the ground.

Probably a wive's tale or my imagination.

Hope you're around this week.... I've got a theoretical question to ask and can't figure out.... but I've got to think it out to try and ask it as clearly as I can.

Best
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Old 06-24-2013, 03:02 PM   #11
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Thanks to all for your responses and info. Much clearer now. I still do not know how to properly use this forum.If there is a way to respond to individuals I am not sure how to do that. So my thanks goes out to all. This forum is the best.
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Old 06-24-2013, 03:10 PM   #12
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Peter, looking forward to your theoretical question and all the pro's responses. Always learning also
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Old 06-24-2013, 06:15 PM   #13
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Originally Posted by MTN REMODEL LLC View Post
MPOUL.... Much better and more accurate description than I typed (the use of NEVER).

I guess I was thinking of hearing some strange story of the pole and house GEC grounding in close proximity with strange earth conditions (like maybe salty or full of iron or something) whereby the system was grounding to neutral technically through the ground.

Probably a wive's tale or my imagination.

Hope you're around this week.... I've got a theoretical question to ask and can't figure out.... but I've got to think it out to try and ask it as clearly as I can.

Best
The "never" might be a little strong. There could be some circumstances where a grounding electrode could clear a fault - but it's certainly unusual, and not supposed to work that way. A grounding electrode would need to have less than 6 ohms of impedance to flow 20A at 120V, and I have not heard of anyone actually achieving that low of an impedance with a regular ground rod or two. It's usually many times that.

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