bonding metal water piping conductor size?

[ritelec]

If there are no grounding electrodes on premises and a 200 amp 120/240v service is installed, there would be a made electrode with two ground rods driven and a #6 cu jumped between the two and attached to the system neutral.
250.104(A). What would be the size of the bonding jumper to the metal water piping? Would it be based of 250.102(C)(1) which would be #4 cu ? Or would it be based some how from 250.104(B) which directs you to 250.122 #6 cu?
Or none of the above?

To add on. Just checking that when sizing for the GEC, I should look at the 250.66 chart and 1100kcmil and ANY WIRE SIZE OVER is a 3/0 cu gec.
250.102(C)(1) is strictly bonding and jumping, and has nothing to do with gec.

Thank you

 

[LarryFine]

Made electrodes never need larger than #6 cu.

 

[ritelec]

Made electrodes never need larger than #6 cu.

Ground rod max #6cu. Other made electrodes should be sized as per 250.66 I would think.

with NO other electrodes except for the two made electrode (ground rods) What size wire is required to bond the water pipe system?

Thank you

 

[LarryFine]

with NO other electrodes except for the two made electrode (ground rods) What size wire is required to bond the water pipe system?

For 200a, #4 cu is adequate.

 

[ritelec]

Made electrodes never need larger than #6 cu.

250.66 (A) and 250.53(E) Rod, Pipe or Plate #6 cu Thank you.

(although H2O is pipe that is not the pipe they are referring to correct? That would be 250.53 (D)


Question: well, plastic pipe. what size bonding wire to copper water system?

 

[ritelec]

For 200a, #4 cu is adequate.

:- ) adequate or required 250.102(C)(1) correct?

 

[LarryFine]

Question: well, plastic pipe. what size bonding wire to copper water system?

The same, regardless of whether the piping system qualifies as an electrode.

 

[LarryFine]

:- ) adequate or required 250.102(C)(1) correct?

I meant large enough to meet requirements, yes.

 

[ritelec]

The same, regardless of whether the piping system qualifies as an electrode.

Thank you

 

[tom baker]

For 200a, #4 cu is adequate.

Most of the time, yes but the size of the GEC is based on the ungrounded secondary conductor size.
For example, this question can not be answered with the given information " What size ground for a 200A service"?

 

[tom baker]

And the explanation is it could be a long secondary service with 500 KMCL conductors. Most, but not all dwelling unit services are 4/0 4/0 2/0 Al

 

[Strathead]

If there are no grounding electrodes on premises and a 200 amp 120/240v service is installed, there would be a made electrode with two ground rods driven and a #6 cu jumped between the two and attached to the system neutral.
250.104(A). What would be the size of the bonding jumper to the metal water piping? Would it be based of 250.102(C)(1) which would be #4 cu ? Or would it be based some how from 250.104(B) which directs you to 250.122 #6 cu?
Or none of the above?

To add on. Just checking that when sizing for the GEC, I should look at the 250.66 chart and 1100kcmil and ANY WIRE SIZE OVER is a 3/0 cu gec.
250.102(C)(1) is strictly bonding and jumping, and has nothing to do with gec.

Thank you

So first, let's talk semantics. metal water piping is a grounding electrode when in direct contact with the earth. At that time, the GEC is sized per 250.66. If you are talking about exposed metal pipe, that does not have an underground metal component 10 feet long, then it is just non-current carrying metal that "may become energized." or not. Like all other non currrent carrying metal, it is only required to be bonded to the grounding system with a grounding wire large enough to carry the fault current that may energize it. So, for example, in a typical house with an electric water heater, it may become energized by that circuit, or the garbage disposal or the dishwasher, both smaller. #10 would be the size. If there is a solid ground connection between the equipment ground on the water heater and the water piping then IMO it is already bonded, but some jurisdictions interpret this more stringently.

 

[LarryFine]

If you are talking about exposed metal pipe, that does not have an underground metal component 10 feet long, then it is just non-current carrying metal that "may become energized." or not. Like all other non currrent carrying metal, it is only required to be bonded to the grounding system with a grounding wire large enough to carry the fault current that may energize it. So, for example, in a typical house with an electric water heater, it may become energized by that circuit, or the garbage disposal or the dishwasher, both smaller. #10 would be the size. If there is a solid ground connection between the equipment ground on the water heater and the water piping then IMO it is already bonded, but some jurisdictions interpret this more stringently.

Not here. We'd never get away with bonding a metallic plumbing system with only #10 cu for a 200a service; we need #4 cu (or equiv) either way, whether or not the internal plumbing qualifies as an electrode.

In fact, I investigated and reported on a fire after a storm caused a POCO primary to hit secondary and service conductors, because the #10 EGC in the water-heater was the only connection between the electrical and plumbing systems. The fire was caused by the EGC melting and igniting the filler and sheath, then nearby wood.

 

[augie47]

So first, let's talk semantics. metal water piping is a grounding electrode when in direct contact with the earth. At that time, the GEC is sized per 250.66. If you are talking about exposed metal pipe, that does not have an underground metal component 10 feet long, then it is just non-current carrying metal that "may become energized." or not. Like all other non currrent carrying metal, it is only required to be bonded to the grounding system with a grounding wire large enough to carry the fault current that may energize it. So, for example, in a typical house with an electric water heater, it may become energized by that circuit, or the garbage disposal or the dishwasher, both smaller. #10 would be the size. If there is a solid ground connection between the equipment ground on the water heater and the water piping then IMO it is already bonded, but some jurisdictions interpret this more stringently.

Certainly not the case here either. 250.104 > 250.102

 

[Strathead]

Certainly not the case here either. 250.104 > 250.102

My interpretation was that "The metal water piping system" is the same one referred to in 250.52. I can see that isn't so, but there is another code thing. There is nothing addressing sections of metal water piping separated by non metallic fittings. The code needs an update.