ECN Forum Forums Code Related Discussion Building Codes for Electricians Running romex in same joist space as water?

I'm re-routing some circuits on a residential kitchen project, and was wondering:

Can you place electrical runs in the same wall cavity with plumbing? Good/bad practice? Could this be against code in some areas?

Yes, but I cannot quote an article to back it up. I know it is done all the time and I would not hesitate to do it myself. Someone else may disagree and provide an article for us. But I think the answer is yes.

I don't see anything against doing so, but experience has suggested a few complications you'll need to address.

Pipes take up space. This can mean there's no room for a box, anchoring the cables can be difficult, and that the cables will need additional protection when the piping pushes them too close to the wall.

I had a HO/plumber who forbid me from running romex in the same stud/joist space as his copper pipes. He claimed electrolisis (sp?) causing pinholes in his copper. He was/is the only plumber that ever identified this as a problem. BTW I run romex in the same bays as plumbing.

Welcome aboard excellencee, from another member from the Commonwealth of PA.

Ian A.

You can. However, if the spacing is tight, you might want to consider the ambient temperature if you find that your cables are physically touching the hot water pipe. In that case de-rating may be required, depending also on the length of the contact.

In the same joist/stud bay? Sure. I've worked with so many plumbers I couldn't begin to take a swing at the number, but I've never heard anything about electrolysis or any such thing like that.

Touching? No. Hot water, cold water, doesn't matter. Not a good idea. Vibrations, heat, cold, etc. There are too many variables to even consider doing this. You can get around them without problem. If not, at least use some pipe insulation jacket between your wire and the pipes.

Good Luck!

We do it all the time over here, where hot-water central-heating systems are the most widespread so it's common to have copper pipework running all over the house, not just in the kitchen/bathroom areas.

Plumber often wrap BX to prevent electrolosis but romex is no problem as it is insulated. excellencee's HO/plumber was thinking bx but he was a plumber and what does a plumber know about electrical installations ;-)

I have first hand experience with a hot water pipe going to the shower, melting into the range feed in my parents house.The house was built in early 70's. this happened probably 6 years ago. The problem most likely started as soon as the house was occupied. But over time the romex jacket and conducter jacket was melted. the only reason for finding the problem was a random shock when getting in the shower, and touching any grounded metal around it. I.e the handle, or drain. I've never seen this problem anywhere else. From then on I always maintain a healthy spacing when running romex anywhere near hot water pipes.

I have seen the same as WireNuts. Mostly,only. with heating pipes, These things are running 180+D FH. Where as the domestic HW is only 120.

I aswell keep a safe distance away from any of them.

WireNuts, how hot was that hot water pipe?? It would take a steam line to melt through the 90C-rated insulation in NM-B, but most people don't even set their hot water heaters above 60C. And even if the romex did melt through and short out to the pipe, that *should* solidly ground it to the GEC and short-circuit trip the breaker.
BX isn't going to cause electrolysis, either, though. I think some plumbers are just paranoid

I can see a chance for electrolysis with bx, a steel or aluminum jacket touching a copper pipe throw in a little moisture from condensation and you have a instant battery. This probably would only happen in an exterior wall.

That wouldn't create electrolysis, though, only galvanic corrosion of the exterior of the copper, and not pinholes. There's really nothing you can do to a copper pipe to create electrolysis in it. Any interior pitting of the pipe is completely unrelated to any electrical cabling that might happen to be nearby.

Article on the actual causes of pinhole leaks is here, and it has nothing to do with electrical wiring:

http://www.toolbase.org/Building-Systems/Plumbing/copper-pinhole-leaks