Grounding Electrode Conductor

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dwagener

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coarsegold,CA.
First here is my situation: I have a large building and within this large bulding I have several smaller stores (strip mall). A new water service was brought in for one store and only that store. The electrical inspector wants me to run a grounding electrode conductor from that store to the main switch board for all the stores. The main switch boards has already been bonded and grounded for 25 years. My space has a 200 amp service in it. I have a number 6 equipment ground. I ran a number 4 from my sub panel in my space to the water and bonded it. The inspector said if my number 6 was a number 4 it would be ok, but since it is not he is say I need to increase the number 6 to a number 4. The main service is 1000 amps, if this is the case shouldn't I run a 3/0 or do I need to do that at all. I am thinking I should just need to bond the water.
 
I'm confused by your information. Is the 200 amp panel in the store a service or a subpanel? A sub panel would only require an EGC in with the feeder to it and possibly a bonding jumper to the water piping system within that store space. Does this feeder originate at the 1000 amp service?
 
the 200 amp sub panel for this space originates from the 1000 amp msb.The water in the space was originaly tap off from an adjacent tenant and not metered.So a new water service was brought in metered outside out side the space .the new water service meets the requirement of a grounding electrode it is metal and in the ground for more than 10'.but it only feed this space and is isolated from all other metal piping systems.
 
the 200 amp panel is a sub panel fed from the 1000 amp msb for the building.The suite /space had an existing water service in it but was not metered.A new water service was added for this space feeds only this space and is isolated from the existing buildings water service.This new water service meets grounding electrode requirement but was added after main service for building was installed inspected and signed off,main service has gec to buildings main water servicenow
 
Since the water qualifies as an electrode it must be added to the already existing grounding electrode system. At that point you are done.

Technically you could use 250.104(A)(2) to allow bonding of the 2nd water service, but that is not the intent of that section. Once you have connected the 2nd water service to the grounding electrode system, there is no point to bonding the 2nd water service again.
 
the problem is getting back to the main service with the new gec which I feel would need to be sized per 250.66 but the inspector say he would let it go if my egc in my 200 amp sub panel was #4 instead of #6 .because I tried 250.104 bonded to sub panel.
 
How is the current grounding electrode system done?

Is there structural steel in the building?

If there is just bond the water to the structural steel with a conductor as per table 250.66 and your done.

Joe Villani
 
dwagener said:
the problem is getting back to the main service with the new gec which I feel would need to be sized per 250.66 but the inspector say he would let it go if my egc in my 200 amp sub panel was #4 instead of #6 .because I tried 250.104 bonded to sub panel.
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I'm only going to advise as to what the Code requires. What your inspector will allow is between you and him.

The structural steel is a good idea. That would save you running 3/0 all the way back to the service.
 
dwagener said:
the problem is getting back to the main service with the new gec which I feel would need to be sized per 250.66 but the inspector say he would let it go if my egc in my 200 amp sub panel was #4 instead of #6 .because I tried 250.104 bonded to sub panel.
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Your partly correct in that if the water pipe meets all the requirements of 250.52 as ?an electrode? that it must be a part of the electrode system, but this one also needs a supplemental electrode with it (250.53(D)) or it will be incomplete and a violation. Your case may already have another electrode though.

We always have to bond water regardless if it?s an electrode or not as per 250.104. The conductor in either case is sized the same from Table 250.66 and the question to always answer is ?what size phase conductor is serving or feeding??

If this water pipe is truly autonomous from the rest of the water system I would say you would size the GEC as per your feeder phase conductor and not the service, just like an out building.

I think 250.104(2) applies to your installation meaning your EGC includes the duel purpose of a GEC as well and this would be code compliant.

What size is your feeder?
 
dwagener said:
the problem is getting back to the main service with the new gec which I feel would need to be sized per 250.66 but the inspector say he would let it go if my egc in my 200 amp sub panel was #4 instead of #6 .because I tried 250.104 bonded to sub panel.
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Why would he allow you to use only a #4 to bond the new water pipe. A 1000 amp service would likely require a #3/0 GEC to a water pipe.
 
infinity said:
Why would he allow you to use only a #4 to bond the new water pipe. A 1000 amp service would likely require a #3/0 GEC to a water pipe.
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Rob,

I think he's applying 250.104(A)(2), with this it's just like a detached building.
 
tryinghard said:
Rob,

I think he's applying 250.104(A)(2), with this it's just like a detached building.
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But how do you get around the fact that a new water pipe would be required to be connected to the existing service since it's in the same building?
 
tryinghard said:
Your partly correct in that if the water pipe meets all the requirements of 250.52 as ‘an electrode’ that it must be a part of the electrode system, but this one also needs a supplemental electrode with it (250.53(D)) or it will be incomplete and a violation. Your case may already have another electrode though.

We always have to bond water regardless if it’s an electrode or not as per 250.104. The conductor in either case is sized the same from Table 250.66 and the question to always answer is ‘what size phase conductor is serving or feeding?’

If this water pipe is truly autonomous from the rest of the water system I would say you would size the GEC as per your feeder phase conductor and not the service, just like an out building.

I think 250.104(2) applies to your installation meaning your EGC includes the duel purpose of a GEC as well and this would be code compliant.

What size is your feeder?
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I thought 250.104 let you size the bond per table 250.122 (Idon't have my code book with me right now.)the size of the 200 amp feeder for my sub panel are 3/0.also I did drive a ground rod.
 
infinity said:
Why would he allow you to use only a #4 to bond the new water pipe. A 1000 amp service would likely require a #3/0 GEC to a water pipe.
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I'm with you.I think if this is going to be part of the grounding electrode system it needs to be done correctly.I just thought that 250.104 would meet the requirements in my mind and was perfectly safe,and cost efective for the customer
 
infinity said:
But how do you get around the fact that a new water pipe would be required to be connected to the existing service since it's in the same building?
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I believe this situation complies with 250.104(A)(2) because the water pipe is not connected to the served buildings water piping system; it sounds completely separate.

The application of 250.104(A)(2) would meet the requirement of 250.50.

250.104(A)(2) is like a detached building in the sense that if you feed a detached building that includes a water pipe electrode, the water pipe electrode will be part of the grounding electrode system through the feeding EGC. In other words the grounding conductor is not required to be larger than the (phase) circuit conductors, this will still enable 250.4(A)(1) as well as 250.122(A).
 
dwagener said:
I thought 250.104 let you size the bond per table 250.122 (Idon't have my code book with me right now.)the size of the 200 amp feeder for my sub panel are 3/0.also I did drive a ground rod.
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250.104(A)(2) does allow you to use Table 250.122 so if you feed from a 200A your EGC must be a #6 cu minimum, #4 cu is not required here.

I understand 250.104(A)(2) to allow the additional water pipe electrode to become part of the existing system through the feeder EGC, just as if you were feeding a detached building that included another electrode.
 
tryinghard said:
I believe this situation complies with 250.104(A)(2) because the water pipe is not connected to the served buildings water piping system; it sounds completely separate.

The application of 250.104(A)(2) would meet the requirement of 250.50.

250.104(A)(2) is like a detached building in the sense that if you feed a detached building that includes a water pipe electrode, the water pipe electrode will be part of the grounding electrode system through the feeding EGC. In other words the grounding conductor is not required to be larger than the (phase) circuit conductors, this will still enable 250.4(A)(1) as well as 250.122(A).
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Ok well it sounds like it's all in the same building to me:

I have a large building and within this large building I have several smaller stores (strip mall). A new water service was brought in for one store and only that store
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By taking the single building approach the new water pipe is now a "present" electrode (250.50) and must be connected back to the 1000 amp service directly or to another electrode service the service. If they're truly separate buildings then I agree that the rules are different. If not the GEC must go from the new "present" electrode back to the service. This would require that GEC to be sized according to 250.66 based on the SE conductors for the 1000 amps service.
 
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