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Re: [TowerTalk] dissimilar metal in ground

Subject: Re: [TowerTalk] dissimilar metal in ground
From: Jim Lux <>
Date: Sun, 18 Dec 2011 10:57:39 -0800
List-post: <">>
On 12/16/11 8:35 PM, Randy wrote:
> Hans:
> I am not conversant in the requirements of the NEC or any other
> electrical codes, but, be
> advised that in many/most/all installations, the copper (or galvanized)
> plumbing pipe of the
> home may well also be used as a "ground".

It's been a fair number years since the cold water pipe was legal for 
use as the grounding electrode.  (service lines being made of plastic, etc.)

However, in general, the plumbing is required to be "grounded".. Part of 
the whole thing of making sure that the floor and things you might touch 
while standing barefoot are at the same potential.

Same reason as having a green wire ground on appliances.

  Sometimes just the cold line,
> but I've often seen
> the hot and cold lines electrically bonded together on the lines above
> the water heater here
> in Florida.

There is typically a insulating bushing between the water heater and the 
hot water pipes, to prevent galvanic action from corroding the water 
heater (there's a sacrificial electrode in the water heater, too).

However, since you don't want faucets to be "hot" electrically, it's not 
uncommon for there to be a jumper between hot and cold lines.

> I also admit ignorance as to when it was, or if it might still be
> permissible, but I've seen plenty
> of homes with a piece of plain steel rebar as the electrical "ground" rod.

Rebar as a ground rod wouldn't be legal.  Rebar sticking out of a 
concrete foundation would be ok, as part of a Ufer ground (aka Concrete 
Encased Grounding Electrode).

Ground rods (of any kind) are deprecated as the grounding electrode (in 
California, you can't use just a ground rod or water pipe as the electrode).


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