Panel Grounding Wire

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  #1  
Old 11-06-04, 06:39 AM
jjrick
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Panel Grounding Wire

I know that the NEC says you must run a grounding wire from the panel to within 5 feet of the main water pipe entrance. I noticed that on my panel the grounding wire goes up and attatches to a water pipe directly above the panel, however, the main water entrance is on the other side of the basement. Where the water pipe comes into the house there is another wire that looks identical to the grounding wire clamped on the pipe about 6 inches in. This wire is about 2 feet long and is clamped again about 1 foor above the meter.

I have no idea but I'm guessing this was code when my house was built in 1971 for adequate grounding. If so, is this still considered safe and if not why? Would it be recommended to run a new grounding wire all the way from the panel to within 5 feet of the main water entrance?

Any advise would be greatly appreciated.

Thanks
 
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  #2  
Old 11-06-04, 07:22 AM
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The short wire is a bonding jumper to maintain the ground around the meter.
 
  #3  
Old 11-06-04, 03:51 PM
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As Joed said, the wire around the meter is there to maintain the electrical path around the meter. This is normal, and required.

The rest of the setup is no longer up to code. I am not sure if it ever was up to code or not. To be legal now, the wire from the panel would need to be run all the way a location where the pipes enter the basement.
 
  #4  
Old 11-07-04, 06:08 AM
jjrick
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Thanks for the info...my panel is 100A so is green 6g wire adequate or can I go smaller.

Also, Id still like to know if it is dangerous the way it currently is. I checked with my neighbor and his house is exactly the same.

JR
 
  #5  
Old 11-07-04, 08:37 AM
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My service entrance in my garage has only a metal rod in the ground 2 feet from the shop driven in the ground. A bare copper wire runs from the service panel to this rod. Is this ok and enough??
 
  #6  
Old 11-07-04, 09:36 AM
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If the incoming water line is metal and in connection with the earth for at least ten feet, it must be used as the primary grounding electrode. Does your water pipe meet this condition? Perhaps your water line up to your house was replaced at some time in the past with PVC?
 
  #7  
Old 11-07-04, 03:33 PM
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John
No this is to my stand alone garage, 200 amp service with it's own meter.
There is a water line to a sink in the garage 40 ft from panel but pvc.
John1
 
  #8  
Old 11-07-04, 08:08 PM
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Sounds like you're good.
 
  #9  
Old 11-08-04, 04:11 AM
jjrick
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I'd still like a reply for questions please...
All anyone has addressed is the bonding for the water meter.
 
  #10  
Old 11-08-04, 04:41 AM
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The copper pipe itself is entirely fine as the 'grounding electrode conductor', connecting from your panel out to the 'grounding electrode' (the pipe actually in the ground).

It no longer meets the NEC to do an install this way, but not because the copper pipe is itself insufficient, but instead because it is now common to replace damaged copper pipe with _plastic_ of some sort. This sort of install is still permitted in industrial situations where strict management procedures can guarantee that the pipe will remain copper.

As long as your pipe is copper all the way, then the installation is safe. If, when it was installed, this sort of install met the then current version of the NEC, then it is legal. If you ever have any plumbing work done on this section of pipe, you will need to make sure that it remains electrically continuous, or you will have to add a proper ground conductor following the 5' rule.

-Jon
 
  #11  
Old 11-08-04, 05:01 AM
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One other point that should be made, and it also will apply if you have to move this existing wire.

Current code requires two methods of grounding. The incoming water pipes must be used (when they can be), and at least one other method must be used. This second method is usually a copper ground rod.
 
  #12  
Old 11-08-04, 09:21 AM
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Jjrick,

I don't see where anyone has addressed the issue of your panel ground being attached to a water pipe near the panel. First and foremost I would remove any and all grounds that are connected to water piping beyond the 5-foot rule. This can energize your water piping and shock somebody in the house. While it is rare for persons to get shocked by touching their faucets, bathtub, etc., it is certainly possible, which is why the NEC does not allow it. For your family's safety please remove the panel ground from your water piping and run it all the way to the incoming main within 5-feet of entrance.

For a 100 amp service, #6 AWG ground is required. Don't go smaller.

Also, as folks in here have pointed out, there is a possibility in any community that the water dept. has replaced your water lateral with PVC. They ordinarily will connect to your existing lateral outside your house, and you would have no way of knowing unless you observed the construction. It is also possible that if your lateral was replaced, they could have left you with 10-feet or more of your original metalic water main. Then it would be in contact with the Earth for a minimum of 10-feet and it is considered a proper grounding electrode. I personally would like to see a proper ground rod that is connected directly to your panel and also bonded to your metallic water piping. It's not that much work but to me is a great deal of peace of mind.

JuceHead
 
  #13  
Old 11-08-04, 09:38 AM
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Jrick,

Do _not_ remove any of the 'ground' connections to your water system. Adding a 'grounding electrode conductor' that meets current code might be desirable, but is not necessarily required. Adding supplementary ground rods to bring your installation up to current code is similarly desirable but not required if your original installation met then current electrical code.

Juicehead,

There is no danger caused by bonding connections between the main ground bus and the water piping, _anywhere_. If there is a connection between the ground bus and a nearby water pipe, then will not cause a high voltage on the water system. You can run a bonding conductor to any metal pipe of the water system, and if you have an isolated length of metal pipe, you _need_ to run this bonding conductor.

The '5 foot rule' specifically deals with the 'grounding electrode conductor', the connection between the electrical panel and the 'ground rod'. When the water pipe is used as the grounding electrode (as a substitute or supplement to the ground rod), then the GEC must be run to within 5 feet of the entrance of the pipe. This is so that the ground connection won't get interrupted if plastic pipe is installed, and so that if there are appreciable ground electrode currents, so that the plumber won't get shocked when cutting open the pipe.

The '5 foot rule' was not originally part of the code, so depending upon when this service was installed, it may not apply.

-Jon
 

Last edited by winnie; 11-08-04 at 10:26 AM.
  #14  
Old 11-08-04, 09:53 AM
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Jjrick,

I want to make something clear, about what I said regarding removing the present panel ground, which Winnie pointed out. Do not simply remove your panel ground wire from the pipe. Instead, I meant to run your panel ground to within 5-feet of water main entrance AND THEN remove the existing one once your panel is properly grounded.

Jon,

You said "There is no danger caused by bonding connections between the main ground bus and the water piping, _anywhere_. If there is a connection between the ground bus and a nearby water pipe, then will cause a high voltage on the water system.". These two statements, the way I read them, seem to directly contradict one another.

Although I cannot cite chapter and verse, it is my understanding that grounding/bonding to water piping *anywhere* outside the 5-foot rule is forbidden. If this is not correct, can you point me to a specific Article so that I may educate myself?

Juice
 
  #15  
Old 11-08-04, 10:22 AM
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There is no danger caused by bonding connections between the main ground bus and the water piping, _anywhere_. If there is a connection between the ground bus and a nearby water pipe, then will cause a high voltage on the water system.
These two statements directly contradict each other. I left out a 'not' I'll edit my original post, but leave the record of the error in this post.

I cannot from memory quote the appropriate article. If I have time I will look at this later. However if you have a code book on hand, I suggest that you look in article 250. You will find that there are two separate things: connection to grounding electrodes (where the 5 foot rule applies) and bonding of metallic systems, where the 5 foot rule does not apply.

In general, when you have a metallic pipe system that is also a grounding electrode, the grounding electrode conductor must follow the 5 foot rule, and also acts as the bonding conductor. But I don't know of any additional restriction on additional ground bonds to the metallic pipe system.

For example, if you have an electric hot water heater, a ground conductor will run with the feeder/branch circuit conductors that go to that heater. This ground conductor will be bonded to the frame, and the frame will also likely have a metallic connection to the plumbing system. There is nothing that restricts this, as far as I know.

-Jon
 

Last edited by winnie; 11-09-04 at 04:56 AM.
  #16  
Old 11-09-04, 05:09 AM
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JuiceHead,

The NEC references:
250.52(A)(1) is where you will find the '5 foot rule'. Note in the exception below the permission in industrial situations to use the metal piping as interconnection between ground electrodes and the permission to violate the 5 foot rule.
250.53(D) is where you can use metal underground water pipe, continuity is required (jumpers around meters and such), a ground rod is also required, and in some settings the ground rod can simply be connected to the water pipes
250.104(A) requires _bonding_ of metal water piping. It does not specify the 5 foot rule. If your metal water pipes are not suitable to be used as 'grounding electrodes', then you still have to bond to them, but there is no 5 foot rule.
250.104(B) bonding of other piping systems says that you can bond pipes with the circuit that might energize them

-Jon
 
  #17  
Old 11-09-04, 06:19 AM
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Jon,

Thanks for the references.

juice
 
  #18  
Old 11-10-04, 05:37 AM
jjrick
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Hey Juicehead and Winnie...

Thanks for all your replies on my issue, I really appreciate it! It seems really confusing but I think I'm just going to leave it alone. It seems the houses in this neighborhood were all done the some way and I'm sure the way it was done was code at the time. I know there is no PVC between the connection and the water main. I've lived here for 21 years and am also quite certain the incoming water line (underground) has not been changed.

Thanks again for all the info.

jjrick
 
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