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| Subject - Water Pipe Bonding | |
| Electricman | Lets say we have a dwelling that has a well, the water pipe from the well into the dwelling is PVC. The Pvc is attached to a well tank by a brass T. From this brass T the plumber solders a 3/4 copper line on to supply the dwelling with water. DO you size the jumper by 250.66 refrencing 250.104(A) or size by 250.122 refrencing 250.104(B)? Since the bonding jumper is not being used as a service EGC ,(already have 2 ground rods driven in at 6ft apart) the company I work for has always sized this bonding jumper by 250.122, we always pull a # 8 thwn from the well pipe(copper) to the service. |
| kbsparky | What is that well casing made of? IF it is metal, and has 10 feet or more in contact with the earth, then you will have to install a full-sized grounding electrode conductor from your service panel to the well. If the interior plumbing is metal, then it needs to be bonded. 250.104(A)(1) specifically refers to metal water piping, and as such, you will have to use table 250.66 to properly size your bonding jumper. You can use 250.122 to size the bonding jumper(s) to other metal piping but not water pipes 
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| Electricman | I kinda respectfully disagree, Even if the casing of the well is mettalic how do you justify running a seperate bonding jumper out there when there is no mettalic path between the house and the well casing? And wouldn't the Equipt ground conductor run with the well pump circuit cover 250.104(B)? Since the mettalic path of the water pipes originates in the dwelling and has no contact with earth wouldn't 250.104(B) apply and not 250.104(A)? I agree with you on the wording and that is why I am a little confused, not only because of the wording but because we have never been called on this and our jobs have been inspected by at least a dozen or more inspectors. I had read 250.104 a number of years ago and brought this to the attention of an inspector and he said we where ok. |
| Ryan_J | In my opinion, the pipe is a grounding electrode as defined if it is more than 10' in the dirt, and therefore 250.50 and 250.52 require you to use 250.66. The 2005 now includes such metal well casing as an electrode, by the way. :) |
| Electricman | OK, thanks guys I appreciate your help. |
| kbsparky | quote:. That was my thinking, but then I read both 250.104(A)(1) and 250.104(B). The Code does not differentiate between metal water piping in contact with the ground and inside piping not in contact with the ground. As long as it's metal, and contains water, the NEC wants a bonding jumper sized the same as a Grounding electrode conductor. The difference between (A) and (B) is water. As for the metal well casings, I was failed on just that over 20 years ago -- that dang well was over 100 feet out in the yard, with a plastic line coming into the house!!  quote: The inspector quoted 250-81(a) from the 1978 NEC as the basis for the requirement. I had to install a #4 bare copper ground wire out to that well, from the service panel. To add insult to injury, the panel was at the opposite end of the house too! 
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| Electricman | What do yall think about this? http://www.ul.com/regulators/ode/0702.pdf |
| kbsparky | quote: I agree with his assessment. While the Code appears to assume that any interior metal water piping system is also in contact with the earth, and thus requires more stringent bonding, in reality the provisions of section 250.104(B) seem to make sense for a safe installation. Don't think for a minute that I am changing my tune here, I am not. My use and quotes of the Code are to help determine what is required, not necessarily what I think would do the job. Like I said before, I got burnt by what I believed to be an over-zealous inspector over that metal well casing out in the yard. Things like that one never forgets |
| Wirenutz | in my experience, most inspectors are happy if one simply bonds everything. in the residential arena, most romex jockeys will carry #4 bare and use it as both GEC, as well as a bond on the way by anything metallic #4 gets us by the physical damage problem, so we'll even use it on 100A dwellings as there is nothing said about upsizing the kicker is, many times we are just adding a parallel noodle by over-bonding multiple sources, but hey...it makes the powers that be happy |