Thread: Grounding to Galvanized water lines in bathroom

I had a slightly warmed, not heated discussion about 10 years ago with Mr Jerry Peck on this subject.
My point was that grounding to the pipes was better than nothing.
On a recent bath remodel, I was dealing with such a setup.
A screw on the box for the light fixture above the vanity had cut the insulation and started an arc when tightened.
Because the ground was a high resistance ground, it did not trip the breaker and the arc kept on going, burning the insulation from the other wires in the box.
I performed the 50 yard dash to the panel in under a minute and killed the power.
If this had happened with nobody around, the house could have been toast.
If there was no ground to the pipes, there would have been no arc, however, someone could have got a nasty surprise.
Food for thought....

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Tim I realize you are in California, but up here its permitted fwiw in older homes with knob and tube. Can't speak to CA rules but threw out the link for your info.

https://www.esasafe.com/assets/files...s/09-09-FL.pdf

Originally Posted by Tim Lorenson

I had a slightly warmed, not heated discussion about 10 years ago with Mr Jerry Peck on this subject.
My point was that grounding to the pipes was better than nothing.
On a recent bath remodel, I was dealing with such a setup.
A screw on the box for the light fixture above the vanity had cut the insulation and started an arc when tightened.
Because the ground was a high resistance ground, it did not trip the breaker and the arc kept on going, burning the insulation from the other wires in the box.
I performed the 50 yard dash to the panel in under a minute and killed the power.
If this had happened with nobody around, the house could have been toast.
If there was no ground to the pipes, there would have been no arc, however, someone could have got a nasty surprise.
Food for thought....

Tim,

I'm trying to figure out it you are for (possible fire) or against grounding (no fire, but possible shock) and if you are commenting on that existing box ... or was it a new box installed with the remodel ... was not grounded (existing box) or grounded properly (new box).

Originally Posted by Raymond Wand

Tim I realize you are in California, but up here its permitted fwiw in older homes with knob and tube. Can't speak to CA rules but threw out the link for your info.

https://www.esasafe.com/assets/files...s/09-09-FL.pdf

Ray,

CA enforces the California Electric Code, which is, for the most part, the NEC. While the NEC does allow water supply piping to function as the grounding electrode, it does not permit water piping to function as an equipment grounding conductor.

As I am not an electrical engineer, I cannot say whether using the metal water supply piping as an equipment grounding conductor is safe or not. But, it is not allowed.

Originally Posted by Jerry Peck

Tim,

I'm trying to figure out it you are for (possible fire) or against grounding (no fire, but possible shock) and if you are commenting on that existing box ... or was it a new box installed with the remodel ... was not grounded (existing box) or grounded properly (new box).

At the time we discussed this, I suggested that grounding to the water pipe was better than nothing.
This was and existing setup from the early 60s, bare copper wrapped around the nail holding the box to the stud. Apparently a high resistance connection, as it did not trip the 15 amp breaker, but sustained a continuous arc.
Seems to be a trade off, bad ground causes fire, may reduce shock.
Choices, choices, death by fire, death by electrocution....
To be safe, check ground impedance

Too often that galvanized water pipe connects to plastic water line some where else in the house and therefore is not a reliable ground. Grounding comes from the service panel anything is asking for trouble..