Bonding and Grounding Copper Pipes

[gadfly56]

He was talking about a nipple you were talking about a union. There is a difference in continuity of the outer portion there. Nipple is metallic, not sure what kind of metal but apparently something that won't have galvanic corrosion between it and the steel hub on the tank nor to a copper fitting on the outgoing line, but shouldn't interrupt electrical continuity either.

If you're screwing directly to the stub on top of the tank, you're not making a dielectric connection, regardless of the stub being plastic lined. Typical dielectric unions, from what I've found, have a plastic liner that keeps the copper pipe from being in contact with the nut on the union and a o-ring keeping it from contacting the lower lip, breaking the electrical path. If it didn't, it would be much use as a dielectric union, would it?

 

[kwired]

If you're screwing directly to the stub on top of the tank, you're not making a dielectric connection, regardless of the stub being plastic lined. Typical dielectric unions, from what I've found, have a plastic liner that keeps the copper pipe from being in contact with the nut on the union and a o-ring keeping it from contacting the lower lip, breaking the electrical path. If it didn't, it would be much use as a dielectric union, would it?

Correct, There is nipples that supposedly lessen galvanic corrosion but are not electrically isolating like that union is. Since they are not electrically isolating there should be no need to bond around these fittings.

 

[gadfly56]

Correct, There is nipples that supposedly lessen galvanic corrosion but are not electrically isolating like that union is. Since they are not electrically isolating there should be no need to bond around these fittings.

Well, OK, I see that. I just don't want to replace the tank in a few years.

 

[kwired]

Well, OK, I see that. I just don't want to replace the tank in a few years.

I don't believe bonding or not bonding around them (if you have them) should really matter much. Galvanic corrosion is going to be because of DC current that is caused by the dissimilar metals and a little acidity in the water (most potable water is not PH neutral but rather at least slightly acidic) effectively creating a "battery" as the DC source.

 

[Bro8898]

You may get mixed responses on the regulator there. Some may see it as something that likely needs removed or replaced frequently and feels it needs a bond around it others may not. Having a metallic body it shouldn't need additional bonding around it other than because of frequent opening the continuity. I sort of feel this not necessary with water meters myself, but many think we should. IMO that mostly goes back to when you could run the grounding electrode conductor to anywhere on the piping that it was necessary to bond around the meter. Now just make sure you bond on street side of the meter IMO should be sufficient. Meters don't get removed all that frequently. Usually only if they seem to not be registering correctly, or more recent years to replace with one that has remote read capabilities.

Perfect. That’s what I was thinking myself. Exactly what I needed to know. Thank you so much for taking the time to provide that information.

 

[Bro8898]

He was talking about a nipple you were talking about a union. There is a difference in continuity of the outer portion there. Nipple is metallic, not sure what kind of metal but apparently something that won't have galvanic corrosion between it and the steel hub on the tank nor to a copper fitting on the outgoing line, but shouldn't interrupt electrical continuity either.

Most nipples are galvanized steel pipe. The plumbing code says in order to join copper to galvanized you must use a “brass fitting, dielectric fitting or dielectric union” (2015 ipc, 605.24).

 

[zbang]

Now just make sure you bond on street side of the meter IMO should be sufficient.

Does depend a lot on where the water meter is... 'round here they're in the sidewalk (I've got 30' of pipe between house and meter).

 

[gadfly56]

I don't believe bonding or not bonding around them (if you have them) should really matter much. Galvanic corrosion is going to be because of DC current that is caused by the dissimilar metals and a little acidity in the water (most potable water is not PH neutral but rather at least slightly acidic) effectively creating a "battery" as the DC source.

I'm not sure of your point. If you use the dielectric unions, you should bond the hot and cold. If you don't use the unions, then a bond wouldn't be needed, but you'll be doing the hot water tank makers a solid for repeat business.

 

[hbiss]

He was talking about a nipple you were talking about a union. There is a difference in continuity of the outer portion there. Nipple is metallic, not sure what kind of metal but apparently something that won't have galvanic corrosion between it and the steel hub on the tank nor to a copper fitting on the outgoing line, but shouldn't interrupt electrical continuity either.

Most nipples are galvanized steel pipe. The plumbing code says in order to join copper to galvanized you must use a “brass fitting...

Yes, it's coming back to me now. To connect copper pipe to the steel inlet and outlet of the water heater you would use a BRASS sweat female adapter, not the usual copper one. I remember including a picture of my water heater with Pro Press brass female adapters.

I can't see why anybody would use a dielectric union. More money and you usually wind up cutting them out anyway when you replace the heater because the lines never line up. So unions do you nothing in that respect.

Oh, and that thread was from somebody who had corrosion between the pipe nipples and the copper female adapters. Seems it went away with the forum upgrade.

-Hal

 

[zbang]

I can't see why anybody would use a dielectric union. [...]replace the heater

I don't know how water heaters came into the discussion, when I first mentioned the unions, I was talking about them being in the street lateral out near the meter (which is often at the street). I'd heard of water companies requiring them to, well, prevent extra current flowing over their lines. That's a place where they wouldn't want a bypass bond.

 

[kwired]

Does depend a lot on where the water meter is... 'round here they're in the sidewalk (I've got 30' of pipe between house and meter).

Around here they are usually inside the structure, if there is a basement usually in the basement. More recent years they have put remote reading capabilities on them so the "meter reader" doesn't go into the building anymore. They do periodically want to get reading directly from display, particularly with remote display types to ensure both main and remote display are reading same thing.

 

[kwired]

I'm not sure of your point. If you use the dielectric unions, you should bond the hot and cold. If you don't use the unions, then a bond wouldn't be needed, but you'll be doing the hot water tank makers a solid for repeat business.

If you have all metallic piping shower valves and some other fixtures will naturally bond hot to cold, why is any additional bonding jumper needed other than for certain inspectors that like to be right even if it doesn't make sense?