I have a question as to which way would be best to ground this service that we are working on.There was no ufer ground installed when the slab was poured.I have an 800 amp service with the main outside. They recently added a bath on another floor. the plumbing pipe is not in but i belive they are going to bring the pipe trough the wall on the third floor.Since this particular part of the building will also be under ground, can i bring my ground wire out trough an extra 4inch pipe run it along the outside of the building and then back in to catch the pipe?Also since this wire will be run about 100 feet can i also use it as a supplemental ground for my dist panel inside the building? If there is a better way i would gladly like to hear it.Also can i chop some concrete and go to the rebar?
grounding
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bphgravity
Senior Member
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- Florida
Re: grounding
I don't understand exactly what you mean by a bathroom on the third floor but still underground?
A metal water pipe can only be used as a grounding electrode if it is in direct contact with earth for at least 10' and the connection must be made within 5' from the point of entrance to the building. I doubt you can meet this requirment making the connection on a third floor.
I also don't think chopping up the concrete would be a good idea as you can not be certain of the continuity of the rebar you are connecting to. I think that leaves you with using the water pipe where it enters the building or a made electrode of some kind.
I don't understand exactly what you mean by a bathroom on the third floor but still underground?
A metal water pipe can only be used as a grounding electrode if it is in direct contact with earth for at least 10' and the connection must be made within 5' from the point of entrance to the building. I doubt you can meet this requirment making the connection on a third floor.
I also don't think chopping up the concrete would be a good idea as you can not be certain of the continuity of the rebar you are connecting to. I think that leaves you with using the water pipe where it enters the building or a made electrode of some kind.
hurk27
Senior Member
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- Portage, Indiana NEC: 2008
Re: grounding
We have this over on the beach (Lake Michigan) where a house is set into the side of a dune hill. the bottom level can be a walk out to the drive way while the 5th (top) floor can be a walk out to a patio all at grade level.
I would say that running to the water pipe is a must do. and if it requires to run it outside it would have to be a copper conductor but I don't see anything in the NEC that would not allow it. But just one thought you said you have a 800 amp disconnect outside? This is the point where the GEC should be ran to as it is the point where the service grounded conductor is bonded to the EGC's
We have this over on the beach (Lake Michigan) where a house is set into the side of a dune hill. the bottom level can be a walk out to the drive way while the 5th (top) floor can be a walk out to a patio all at grade level.
I would say that running to the water pipe is a must do. and if it requires to run it outside it would have to be a copper conductor but I don't see anything in the NEC that would not allow it. But just one thought you said you have a 800 amp disconnect outside? This is the point where the GEC should be ran to as it is the point where the service grounded conductor is bonded to the EGC's
Re: grounding
Yes, the building is cut out of a big mountain withthe first floor of the front of the building at grade level and the grade slopes up to the third floor at the back of the building.also the ges is at the main disc. outside but being outside doesnt this make it another building, therefore making you put a gec inside also?
Yes, the building is cut out of a big mountain withthe first floor of the front of the building at grade level and the grade slopes up to the third floor at the back of the building.also the ges is at the main disc. outside but being outside doesnt this make it another building, therefore making you put a gec inside also?
hurk27
Senior Member
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- Portage, Indiana NEC: 2008
Re: grounding
Is this disconnect away from the building on a pole? your AHJ should be able to tell you how far this disconnect is allowed before it is considered another building. But if the disconnect is mounted on the building then it is part of this building and the GEC should only connect to this point. If it is away from the building then you would not need to run a water ground to it as it only needs a ground rod or two (25ohm's). But then the building will need the same plus the water pipe GE.
[ October 19, 2004, 12:58 AM: Message edited by: hurk27 ]
Is this disconnect away from the building on a pole? your AHJ should be able to tell you how far this disconnect is allowed before it is considered another building. But if the disconnect is mounted on the building then it is part of this building and the GEC should only connect to this point. If it is away from the building then you would not need to run a water ground to it as it only needs a ground rod or two (25ohm's). But then the building will need the same plus the water pipe GE.
[ October 19, 2004, 12:58 AM: Message edited by: hurk27 ]
Re: grounding
thanks. Yes the main disc is about 60 feet away from the building. One more question if the water pipe happens to come in plastic then two rods will due right?What about a #4 in the trench that is like 60 feet.The pipe that the ground will go trough is also about 60 feet before it gets out of the building.THanks in advance.
thanks. Yes the main disc is about 60 feet away from the building. One more question if the water pipe happens to come in plastic then two rods will due right?What about a #4 in the trench that is like 60 feet.The pipe that the ground will go trough is also about 60 feet before it gets out of the building.THanks in advance.
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