Metallic water piping through out house (plastic supply line)

[Dsg319]

In the situation of a dwelling supplied with a plastic water line but the house is plumbed in using copper I know it doesn’t have to be bonded for use of a GES

But still needs to be bonded as likely to become energized? The EGC supplying the hot water tank circuit would achieve this.

Or is there more to it and how to size it?

Also must there be a jumper between hot/cold lines or is there anything internal to achieve this.

Appreciate any answer also if anyone has the appropriate code section to post.

Thanks in advance.

 

[infinity]

If the metal water piping systen is not an electrode it still is required to be bonded. Look at 250.104(A). The NEC doesn't specially mention a bonding jumper across the water heater but some jurisdictions like here in NJ they require it.

 

[Dsg319]

Thank you!

 

[kwired]

But still needs to be bonded as likely to become energized? The EGC supplying the hot water tank circuit would achieve this.

Or is there more to it and how to size it?

250.104(A) as Infinity mentioned.

Don't know why but water piping system bonding needs sized per 250.102(C)(1), even though you would think many cases the largest overcurrent device that possibly could energize it would be acceptable like for most other piping systems and use 250.122.

Take a dwelling with a 200 amp supply - and no branch circuits over 60 amps kind of no good reason a 10 AWG can't bond a water piping system that is not also a grounding electrode. Unless they figure maybe someday someone could supply say a 70 to 200 amp feeder out of the main panel?? About the only logical reason I can think of. If you increase service capacity the bond conductor needs upsized anyway, as currently written.

 

[Elect117]

250.104(A) as Infinity mentioned.

Don't know why but water piping system bonding needs sized per 250.102(C)(1), even though you would think many cases the largest overcurrent device that possibly could energize it would be acceptable like for most other piping systems and use 250.122.

Take a dwelling with a 200 amp supply - and no branch circuits over 60 amps kind of no good reason a 10 AWG can't bond a water piping system that is not also a grounding electrode. Unless they figure maybe someday someone could supply say a 70 to 200 amp feeder out of the main panel?? About the only logical reason I can think of. If you increase service capacity the bond conductor needs upsized anyway, as currently written.

I think it is because they assume the water pipe might become energized by the supply side of an overcurrent device. Even if it is not an electrode they might assume that metal water pipes for sprinklers (if that even exists) and other things might become energized. In a way to keep it generalized they can safely say that sizing it like a bonding jumper would always allow for the proper fault current or lighting or stray currents etc. would return to the panel and get to the GEC / neutral.

If I am not mistaken, it still does not need to be larger than the neutral if the neutral is reduced in residential.

 

[Elect117]

I just saw this while reading the handbook version on NFPA link,

"Bonding a metal water piping system is not the same as using the metal water piping system as a grounding electrode. Bonding to the grounding electrode system places the bonded components at the same voltage level. "

 

[don_resqcapt19]

I think it is because they assume the water pipe might become energized by the supply side of an overcurrent device. Even if it is not an electrode they might assume that metal water pipes for sprinklers (if that even exists) and other things might become energized. In a way to keep it generalized they can safely say that sizing it like a bonding jumper would always allow for the proper fault current or lighting or stray currents etc. would return to the panel and get to the GEC / neutral.

If I am not mistaken, it still does not need to be larger than the neutral if the neutral is reduced in residential.

I don't think there is anything in 250.104(A) that says that.

 

[Elect117]

I don't think there is anything in 250.104(A) that says that.

You are right. I didn't have the section open. I was mistaken lol.

 

[wwhitney]

I don't think there is anything in 250.104(A) that says that.

OK, but the minimum size grounded conductor for a service to a building, and the minimum size bonding jumper for a metal water pipe system, are both given by the same table, NEC Table 250.102(C)(1). That does mean that the bonding jumper is not required to be larger than the grounded service conductor.

Cheers, Wayne

 

[kwired]

I think it is because they assume the water pipe might become energized by the supply side of an overcurrent device. Even if it is not an electrode they might assume that metal water pipes for sprinklers (if that even exists) and other things might become energized. In a way to keep it generalized they can safely say that sizing it like a bonding jumper would always allow for the proper fault current or lighting or stray currents etc. would return to the panel and get to the GEC / neutral.

If I am not mistaken, it still does not need to be larger than the neutral if the neutral is reduced in residential.

The grounded service conductor can not be smaller than the min required GEC so neutral would never be smaller. Residential has no impact, rule applies to all installations.

 

[kwired]

I just saw this while reading the handbook version on NFPA link,

"Bonding a metal water piping system is not the same as using the metal water piping system as a grounding electrode. Bonding to the grounding electrode system places the bonded components at the same voltage level. "

Correct, the electrode is what is in contact with the soil, and the first five feet inside are technically not the electrode but for the sake of connecting the GEC as well as bonding jumpers to/from other electrodes, it is an extension of the electrode.

If there is no isolating components between the "electrode" and the interior piping you do not need a ny additional bonding connection for the interior piping

 

[Elect117]

The grounded service conductor can not be smaller than the min required GEC so neutral would never be smaller. Residential has no impact, rule applies to all installations.

I think in this instance the water pipe was not an electrode and therefore not a GEC but just being bonded per Art. 250.104. To Wayne's point, it would be the same size. Same concept you mentioned but didn't want to mislead that it would qualify as an electrode.