Di-electric union on water supply

[Rossn]

I am re-plumbing my home, as part of a major remodel, and will be replacing the supply line between the entry point of the home (meter is at the street) and the utility room (and upgrading it from 3/4" to 1").

I had a not-so-good experience in my prior home, by which the neighbor's neutral had failed, and his neutral was fully returning to the power company across the water main, into my home, through my water bond, and out my neutral. I actually detected some current flow at one time in my current home, so I would like to install a di-electric union, which would reduce the chances of any stray currents moving throughout the plumbing in the home.

Does anyone have any concerns or see a code/inspection issue with this plumbing layout:

Supply Tubing Through Wall -> Ball Valve -> Di-Electric Union ->Moen Flo -> Tubing to Utility room

I believe the water bond could be attached to both sides of the ball valve, though I may also have to bond the metal tubing within the home through another means.

Edit: Perhaps the di-electric union doesn't offer much given that the Moen Flo is made of a plastic or composite, and may not conduct.

 

[Hillbilly Bob]

Maybe the reason you haven't received a reply is it's really an electrical question, perhaps best directed to an electrician or your local building inspector.

What you propose has the same effect as splicing in a section of plastic pipe to break electrical connectivity. Dielectric unions are directional, so in an all-copper system, you'd need two joined back-to-back with a compatible nipple. Don't know anything about conductivity of the MoenFlo.

As you post mentions, the big concern is grounding (NEC, primarily 250.50 and 250.104). If the supply is metal pipe in contact with the earth for 10', it counts as a grounding electrode and needs to be connected to the electrical grounding system. If it's plastic coming into the house, it's obviously not a grounding electrode. Metal pipe after (maybe between) your dielectric unions would as you said need to be bonded to the grounding system if it could be energized. How that is done,what wire size, etc. depends on particulars. If you have gas, you need to make sure those pipes are properly bonded, too.

If you break the connectivity of the pipe and rework your grounding system properly, you can shunt stray current around your pipes. If you don't do it right, you can create a really dangerous problem.

Tread carefully.

HB

 

[Sponsor]

 

[wwhitney]

An interior dielectric union is not useful, as the metal piping system on both sides of it will require bonding to the GES, so it will still provide a current path.

What you can do is put a dielectric outside, which in Denver, CO would presumably require digging. Then you don't have a grounding electrode anymore, but the piping system will still be bonded inside. You'd want to make sure you have an alternative grounding electrode (2 ground rods, a UFER ground, some other metal underground piping, etc). But you are supposed to have that anyway for a metal water pipe grounding electrode, because of the frequency with which some water services get replaced with non-metallic water services.

Cheers, Wayne