Bonding the water pipe outside the building

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cohosilver

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I have a question on whether or not it is acceptable, NEC approved, to bond the steel water pipe outside an existing masonry building if that is the only common steel pipe that feeds multiple bathrooms within the building? In addition, if the water pipe is on the other side of the existing masonry building from the load center that supplies the building, is it acceptacle to run a GEC sized by 250.66 from the water pipe just outside the entrance of the building to the building steel and then run a GEC sized by 250.66 from the building steel to the ground bar in the panel? In addition, I would run #6 solid cu from two 3/4"x10' ground rods to the ground bar in the panel. There is no exposed rebar or other pipes such as gas. I am trying to ground and bond a number of existing old occupied masonry buildings used for living quarters, offices, kitchens and shower/bathroom areas up to NEC 2008 code.
 
If the building steel qualifies as an electrode then you will not need the ground rods. Yes you can bond the water pipe and the steel together to form a grounding electrode system and then run a GEC from either back to your service disconnect.
 
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If I may, I agree with Rob but emphasize that your building steel must qualify as an electrode to allow you to connect the water to it and the connect it to the panel. You can not, for instance, use a steel beam sitting on masonry for this purpose (if that is what you have). Take a look at 210.52(A)(2) to assure your steel qualifies as and electrode.
You may find the rods will assist in having it qualify.
 
augie47 said:
If I may, I agree with Rob but emphasize that your building steel must qualify as an electrode to allow you to connect the water to it and the connect it to the panel. You can not, for instance, use a steel beam sitting on masonry for this purpose (if that is what you have). Take a look at 210.52(A)(2) to assure your steel qualifies as and electrode.
You may find the rods will assist in having it qualify.
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Yes I agree. The way I had answered in post #2 it made an assumption that the building steel is an electrode. I've changed that post to reflect that per Augie's suggestion. :grin:
 
Grounding a water pipe outside a building

Grounding a water pipe outside a building

I reviewed 250.52(A)(2) and 250.52(A)(1) and based on the information provided I have determined that the Iron I-Beams are only on top of the masonry structure and that they are not directly tied to earth. The ground rods would be the primary grounding electrodes in my opinion. Can I still connect the GEC from the water pipe to the Iron and then from the Iron to the ground bar or, if the Iron I-beams do not qualify as an electrode grounding conductor, are they required to be bonded?
 
You can not use the steel as a conductor. I picture this as being isolated steel beams sitting on masonry. If that is the case, then in this jurisdiction we do not require them to be bonded. Isolated section so steel are treated differently from a structural steel frame.
If your water pipe is your only existing electrode, you will need to run a GEC to your panel (it can be connected outside) and you will need the rod electrodes as supplemental.
 
The NEC does not specify a primary or secondary electrode. The water pipe, if it qualifies as an electrode must be used. It also must be supplemented by a supplemental electrode which in this case could be 1 or 2-8' ground rods. For the building steel, 250.52(2) will outline if it qualifies as an electrode or not.
 
Grounding the water pipe outside the building

Grounding the water pipe outside the building

I appreciate the help. It seams clear that I should bond the water pipe as it is steel, comes from the ground, and is run inside the masonry. It seams clear that I need to run a GEC from the water pipe back to the panel. It seams clear that the steel beams resting on the masory, even though they are connected together through iron cross bracing, they are not required to be bonded because it isn't part of any structural steel frame. Because I have only the water pipe as a grounding electrode for the building I will need a suplementary ground rod at the panel. Hopefully this sounds correct, if not, please advise. Thanks.
 
cohosilver said:
I appreciate the help. It seams clear that I should bond the water pipe as it is steel, comes from the ground, and is run inside the masonry. It seams clear that I need to run a GEC from the water pipe back to the panel. It seams clear that the steel beams resting on the masory, even though they are connected together through iron cross bracing, they are not required to be bonded because it isn't part of any structural steel frame. Because I have only the water pipe as a grounding electrode for the building I will need a suplementary ground rod at the panel. Hopefully this sounds correct, if not, please advise. Thanks.
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Sounds good. Only thing you'll need to keep in mind is that your single ground rod would require a resistance of 25 ohms or less. Otherwise you'll need two rods.
 
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