Grounding Outside Cutt-Off

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Old 10-19-08, 06:21 PM
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Grounding Outside Cutt-Off

I have to change the grounding at my house. What I plan to do is install a second ground rod, which I'll connect to a the first existing ground rod, then to the panel inside and the incoming cold pipe.

My problem is that the outside 200A cutoff box is presently attached, via its ground bus, to the cold water pipe.
Is this where it's supposed to go????
If not then where?? What's the code on this?

Thanks in advance
 
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Old 10-19-08, 06:35 PM
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Why exactly do you need to change the grounding at your house? Typically, you do not need to change anything regarding the service unless you are upgrading said service, or if something is damaged. Codes are not retroactive, so you are not required to upgrade anything unless you are in the aforementioned circumstance.
 
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Old 10-19-08, 06:42 PM
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Thanks for the reply, Yes I am upgrading. I'm putting in a standby generator, already have a permit, and was told to make sure all my panel grounds were correct as part of the process.
 
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Old 10-19-08, 07:09 PM
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Short answer...

Basically you should check with your local electrical inspector for the grounding requirements for your local area.

Long answer...

What is allowed for grounding is based on what was allowed in past electrical codes (for existing), present electrical codes, and any modifications to the electrical codes your specific town/county/state has.

Also sometimes what your electric company says.

Cold water pipe grounds used to be a good thing, but these days people replace metal main water pipes with plastic pipes!

If the water pipe was your only ground, then you can be left with no ground and a dangerous situation. If the ground remained connected to the house metal cold water pipe and the main electrical "neutral" came loose, then the cold water pipes in the house could become energized and shock someone.

And people replacing main water pipes *should* get a permit to do this plumbing work and the grounding checked at that time, but this is not always the case. It is common to see plumbing work done by a homeowner and electrical grounds disconnected.

Personally I feel the safest grounding is two ground rods placed 6 ft. apart connected together, then a large diameter ground wire run from the closest ground rod to the electric panel. Then the cold water pipe bonded* (connected) to that same closest ground rod.

*There is another common situation with homes and that is the "ground wire killing lawnmower"! You can have a situation where a lawnmower many times hits the ground wire going down the outside wall and eventually breaks it. If the cold water pipe is bonded to the ground rod in this case, then this would also break the connection to the cold water pipe. THEN if the neutral came loose, the cold water pipes would not potentially become energized.

I once saw where a car scraped the side of an office building and broke the ground wire. Those poor ground wires get a lot of abuse!

In my state, before using a cold water pipe as a main ground, you must verify the integrity of the buried metal pipe or use ground rods.

Then I have heard of an electric company which refused to connect the electricity to a new service if a cold water pipe was directly connected to the panel. They only allowed ground rods. Of course it was ok to bond the cold water pipe to the ground rods and this was required.

Also when working on ground wires, always turn off the main power first. There are rare situations where an appliance can be "leaking to ground" and you could get zapped if power is on.
 
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Old 10-20-08, 01:19 AM
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Originally Posted by Bill190 View Post

Personally I feel the safest grounding is two ground rods placed 6 ft. apart connected together, then a large diameter ground wire run from the closest ground rod to the electric panel. Then the cold water pipe bonded* (connected) to that same closest ground rod.
This is what I'm going to do. Back to my quest......how is the outside main cut-off supposed to be grounded.
 
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Old 10-20-08, 09:30 AM
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Basically all grounding should be done at the main panel (with the exception of additional ground rods at remote building subpanels).

The grounding for any subpanels inside should be via a 4th ground wire going back to the main panel.

This is important safety stuff as to how this is all done. Best to take pictures of everything and take them to your local electrical inspector and ask what you need to do. Also open your electric panel doors and take close-up pictures of the label on the door and of the breakers.

What I have to say is not necessarily what your local electrical inspector has to say. Best to get it straight from the "horse"!
 
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