bonding copper lines on shower valves

[mjd1]

i recently finished wiring a house that has all plastic water lines, even the main comming into the house is plastic. the only copper to be found in the entire house is the line from the shower valve to the shower head. this is only a few feet of copper. the hot and cold supply lines are plastic. why is the local inspector insisting that this isolated piece of copper be bonded with a #6 bare back to the panel? what could the possible danger be? a fiberglass tub with a 4' piece of copper behind it....which is attached to plastic water lines....i don't get this one.

 

[infinity]

There is no requirement to bond this pipe to anything. Metallic piping systems require bonding not an isolated piece of pipe. The inspector is incorrect. Ask him for a code reference, a 4' piece of pipe is not a system.

 

[wbalsam1]

Wow! Another inspector making up his/her own rules! How many times I have run in to this.....and I'm an inspector. I see it so much. In New York State, it's up to the code enforcement officials to weed these people out and send 'em packin'. :roll:

 

[NoVA Comms Power]

... Another inspector making up his/her own rules! ...

And requiring that it be a #6 all the way back to the panel too! :-?

 

[wbalsam1]

And requiring that it be a #6 all the way back to the panel too! :-?

Yeah! get that, huh? Additionally, some Building Officials are guilty of the same behavior. It's really bad when you get a rule-making Code Enforcement Official trying to manipulate a rule-making Third-Party Electrical Inspector. Or vice-versa. Now there's some chaos on the project! :grin: :grin: Just sit back and shake your head.......

 

[electricmanscott]

why is the local inspector insisting that this isolated piece of copper be bonded with a #6 bare back to the panel?

what could the possible danger be?.

Because he/she is a moron.

The danger is having this person "inspecting"

 

[infinity]

Because he/she is a moron.

The danger is having this person "inspecting"

Very funny! Maybe this guy should drill and tap the cast iron bathtub to attach a lug and his #6 wire to it.

 

[dbuckley]

I think it is advisable to bond that bit of metal pipe, though not with #6, whatever the interpretation of code says.

The pipework is all plastic, and thus the water (which conducts electricity a bit) is a flowing conductor in insulated pipework (think of it as a liquid wire) that can carry a potential difference into your equipotential zone, and thus deliver a tingle, if the showerer touches something that is equipotential-ish.

 

[electricmanscott]

Sarcasm?? I hope

 

[stickboy1375]

Haha, I thought it was pretty funny...

 

[winnie]

I do not believe that an isolated section of copper plumbing should be considered a 'piping system', though if the inspector is calling 'a pipe, a mixing valve, and a shower head' a piping system, then no rules are being 'made up'. If the inspector is arguing that this short section is a metallic water piping system, then code requires that it should be bonded.

I believe that equipotential bonding around a bathtub, including all metal fixtures, supply pipes, and _drain_ pipes, is a _good idea_. I've seen enough reports of strange tingling in the shower, the EPRI research on 'contact current', etc. to convince me that this is worth doing. In this I agree with dbuckley.

Having said the above, I do not believe that code requires this sort of bonding. In fact, I believe that the requirements of current code, as generally interpreted, actually make equipotential bonding issues _worse_.

Under current code, if you have standard metal piping, you would bond the copper supply pipes but _not_ cast iron drain pipes, which IMHO actually _increases_ hazard at the tub (by having some bonded metal and having separate _non-bonded_ metal in contact with earth.

The focus on the very large conductors for bonding metal water pipes is a historic artifact from the use of common metal underground water supply, and the use of the water pipe as a ground electrode. When you have multiple services in multiple buildings, all sharing the same metal water pipes, then it makes sense to size the bonding conductor to this 'backup neutral' for the fact that it will very likely carry a significant portion of the neutral current. But for an isolated segment of water pipe, such a large conductor simply makes no sense.

IMHO as we change over to plastic piping, drainage, and vent pipes, code will have to evolve where we actually do have 'equipotential bonding' in bathrooms, but the bond back to the panel will be reduced to the 'circuit likely to energize' the bathroom, eg. the bathroom circuit EGC. Such a code change is not currently supported by the evidence, but my gut tells me that we should be looking in this direction.

-Jon

 

[ecirplr]

Wouldn't Art 250.104 cover your question.Even if the system is plastic the metal piping is required to be bonded.

 

[tom baker]

Perhaps this will help your inspector, who is wrong, by the way.
In Washington State we have a state NEC rule that does not require isolated metal water piping stub outs to be bonded.
Ask the AHJ what the danger is. How will that piping become energized?

 

[George Stolz]

Wouldn't Art 250.104 cover your question.Even if the system is plastic the metal piping is required to be bonded.

Only metal piping systems are covered by 250.104. A system of metal pipes.

 

[infinity]

Only metal piping systems are covered by 250.104. A system of metal pipes.

Agreed. This eliminates the requirement to bond short sections of piping as the wording specifically says systems.

 

[macmikeman]

Them old rubber bathtub drain plugs have a metal ring attached to them for a pull handle. I wonder how to get a bonding lug onto one of them?

 

[infinity]

Them old rubber bathtub drain plugs have a metal ring attached to them for a pull handle. I wonder how to get a bonding lug onto one of them?

Or the cast iron or steel tub for that matter.