Ground Paranoia

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  #1  
Old 04-08-13, 07:57 AM
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Ground Paranoia

Due to the paranoia state (just kidding, I love this stuff) from reading all this useful and helpful information on this site and the dilapidated condition of the ground to the water supply, I've decided to show my love for my house.

My Meter and main disconnect are about 20 feet away from the water line so I am thinking to break some concrete (unfinished basement), dig a little 8" trench, run a 1/2 rigid conduit underground from the meter to the water supply, run a #4 solid copper wire (overkill) and connect my ground. Besides the ground wire size for 100 amp service, does something sound out of the ordinary here gents?

All comments good or bad are appreciate.
 
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  #2  
Old 04-08-13, 09:19 AM
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Besides the ground wire size for 100 amp service, does something sound out of the ordinary here gents?
Yes. The bonding conductor should be run inside the structure, in the open, from the enclosure that has the first overcurrent protection device.
 
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Old 04-08-13, 10:21 AM
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Yes. The bonding conductor should be run inside the structure, in the open, from the enclosure that has the first overcurrent protection device.
OK so I run it from the service disconnect switch thats in one room, uncovered, through the wall to the water supply pipe in the other room, right? Don't put it in conduit and don't bury it right?
 
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Old 04-08-13, 10:51 AM
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Yes, that's right. Connect to the cold water inlet within 5' of where it enters the house. You may need to install some bonding jumpers across a pressure relief valve or any other gaps in the copper(?) to pick up everything.
 
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Old 04-08-13, 11:18 AM
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For arguments sake, lets just say that the inspector has approved the wiring and ground of course and I just want peace of mind,
would burying the #4 solid ground wire in the floor in rigid conduit to the supply line work? You would think that protected in conduit and buried under the floor would be better.
 
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Old 04-08-13, 11:30 AM
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Not really. No uninsulated conductors allowed in conduit, for one thing. Why not run it overhead?
 
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Old 04-08-13, 11:35 AM
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Why wouldn't an uninsulated conductor used for grounding be allowed in conduit?

I guess overhead is an option. Run it in the ceiling drywall. Or no?
 
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Old 04-08-13, 11:37 AM
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Yes. Well, above the drywall or on the drywall.
 
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Old 04-08-13, 12:09 PM
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Yes. Well, above the drywall or on the drywall.
I find it strange that it is OK to cover in drywall but not in the floor covered and protected.
 
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Old 04-08-13, 12:40 PM
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Why wouldn't an uninsulated conductor used for grounding be allowed in conduit?
OK. Galvanic corrosion, galvanic bonding, an unintended additional path to ground.. off the top of my head.

Have you read the article I posted the link to?
 
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Old 04-08-13, 12:46 PM
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I find it strange that it is OK to cover in drywall but not in the floor covered and protected.
Natural and organic aren't the same thing. Enclosed and protected aren't the same thing.

Many of us have a question about something in the code from time to time. That doesn't mean that we're prepared to assert that our knowledge is superior to the knowledge of the wise people who write, amend, revise and interpret the code.

Mike Holt is one of those people.
 
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Old 04-08-13, 01:20 PM
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IF you run the grounding electrode conductor through metallic conduit you MUST have grounding bushings at either end of the conduit and connect the conductor to these bushings. That way the conduit itself is also part of the grounding electrode conductor system.

This requirement does not apply (of course) if you use a non-metallic (electrically non-conductive) conduit. This is why on those rare occasions that a grounding electrode conductor needs to be protected from physical damage PVC conduit is normally specified.
 
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Old 04-08-13, 02:03 PM
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Not to muddy the waters but there is also armored ground cable. Maybe one of the pros can provide information on where and why to use that.
 
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Old 04-08-13, 02:14 PM
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Not to muddy the waters but there is also armored ground cable.
I haven't thought of that stuff in years!

Scarce as hen's teeth and ruinously expensive. I've only used it once, and I don't recall if that was the corrosive environment, the length of the conductor (9 stories), the need to minimize any potential for arcing or a need to limit physical damage to the conductor. All of these challenges were present and the choice may have come from a combination of them.
 
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Old 04-08-13, 02:16 PM
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IF you run the grounding electrode conductor through metallic conduit you MUST have grounding bushings at either end of the conduit and connect the conductor to these bushings.
It also doesn't mean that the conductor can be uninsulated, IIRC.
 
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Old 04-08-13, 03:43 PM
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The code has stated for as long as I can remember that any grounding electrode conductor smaller than #6 must have physical protection. That armored ground cable, which WAS an uninsulated conductor, was common on 60 and 100 ampere services.

Nash, I've been meaning to ask you about that prohibition on using uninsulated conductors in a conduit system. Do you have a code reference for that? I have always used insulated grounding conductors but at least part of that is because that is what I had and I would have had to specially buy bare.
 
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Old 04-08-13, 04:10 PM
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Not offhand, Furd. I can look later if Joe doesn't come up with it first.
 
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Old 04-08-13, 04:18 PM
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See my confusion? If you can't have bare wire in conduit isn't armored ground wire a bare wire in flexible conduit?
 
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Old 04-08-13, 04:31 PM
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The stuff I remember wasn't. It was bare bendable and had a layer of insulating material between the conductor and the outer sheath, which resembled bendable copper plumbing tubing.

Maybe we're talking about two different materials.
 
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Old 04-08-13, 04:39 PM
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What I am "wanting" to believe based on Furds posts is that if using a #6 or larger bare solid copper ground wire in conduit, rigid metal in my case, it will work as long as I use grounding bushings on both sides. A little wishful thinking here folks.
 
  #21  
Old 04-08-13, 05:24 PM
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If you use #6 or larger there is no code mandate to use conduit of any kind UNLESS the conductor is subject to physical damage. the phrase "subject to physical damage" is definitely subject to interpretation by the local inspector but it is rare that a grounding electrode conductor is deemed subject to physical damage.

If you simply want to run the conduit because you think the bare (or green insulated) conductor is unsightly then use PVC conduit. If you are really concerned about physical damage to the conduit then use schedule 80 PVC conduit.

Honestly, if you can run it behind drywall, through studs or whatever it is okay. The inspector WILL want to see each end of the conductor and MAY want to see it before covered. As far as I know there is no requirement that the grounding electrode conductor OR a supplemental grounding conductor (to the water piping when a ground rod is also used) must be visible for its entire length.
 
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Old 04-08-13, 05:43 PM
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Go ahead and run it in the rigid conduit with bond bushings if you want to. There is disagreement in the industry on this and the NEC doesn't appear to specify. At least I couldn't find it.

That said, I would never do it for the reasons I gave above, BUT if your inspector will approve it then fine. I would definitely ask the inspector before doing the work.
 
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Old 04-08-13, 10:26 PM
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Thanks fr all the attention here guys but now I have another question.

Can I run a bare solid wire in metal conduit #6 or larger as a ground along with other insulated wires without being in violation?
 
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Old 04-08-13, 10:32 PM
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It may not be a violation of the NEC, but will your inspector approve it? Ask first. Tell us what he or she says.
 
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Old 04-09-13, 12:51 AM
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What I meant to say in my last post is

Can I run a bare solid wire in metal conduit #6 or larger as a ground along with other insulated wires from the main disconnect switch to the sub-panel without being in violation?

And is this something that is not common?
 
  #26  
Old 04-10-13, 12:24 AM
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Below is what I found on a different forum while searching for an answer to my previous post, I hope this helps others.


The Code permits an EGC to be bare or insulated. However, if the conductor is bare, there can be arcing between the bare conductor and the interior of the conduit at points other than the point at which the ground fault occurs. This is due to slight differences in impedance between the raceway & the wire, resulting in potential differences that can result in arcing. Such arcing can damage the phase conductors without adding to the proper functioning of the ground fault circuit. That makes a strong case for the use of insulated EGCs where installed in a metal enclosure.
 
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Old 04-10-13, 05:04 PM
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Thank you!

From that I gather that bare equipment grounding conductors ARE allowed in conduit but they are not a good idea. I'll continue to use insulated conductors.
 
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Old 04-11-13, 11:32 AM
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You answered the question. Good job of digging for it.
 
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Old 04-18-13, 08:13 AM
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This is what looks to be the 10 gauge solid wire that was used on my 100 amp service. It was encased in 1/2" pipe underground going to where the water pipe enters the building.
 
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Old 04-18-13, 06:10 PM
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IF you run the grounding electrode conductor through metallic conduit you MUST have grounding bushings at either end of the conduit and connect the conductor to these bushings. That way the conduit itself is also part of the grounding electrode conductor system.
Furd is exactly right! If the metal conduit (ferrous) isn't bonded at both ends to the conductor, a choke effect is created that can impede the flow of current should a fault occur.
 
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Old 04-18-13, 06:11 PM
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That does look like #10 AWG. Try your wire stripper on it if you want to find out for sure.
 
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Old 04-18-13, 08:33 PM
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After all this back and forth and "open for interpretation", I decided to yank out the solid, bare #4 ground in the galvanized conduit and run a stranded, insulated #6. Paranoia? Yes, I wanna be able to sleep in my own house. So I took a little loss on the solid #4, maybe I'll use it somewhere else, probably not. Maybe I'll give it away or trade it as a favor. Are you guys kidding me? Sometimes peace of mind has a price. Time to move on, I'll make up for it somewhere else if I havent done so already.


IF you run the grounding electrode conductor through metallic conduit you MUST have grounding bushings at either end of the conduit and connect the conductor to these bushings. That way the conduit itself is also part of the grounding electrode conductor system.
Furd is exactly right! If the metal conduit (ferrous) isn't bonded at both ends to the conductor, a choke effect is created that can impede the flow of current should a fault occur.
 
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