This is how I understand a res service is done. If the MBJ in the main panel is removed, I’d have to isolate grounds and neutrals correct?

[newservice]

One rod with the water pipe is not good enough because in some places the metal water pipe is replaced with a nonmetallic pipe and then according to the NEC the single untested rod is not good enough.

Um,...yeah when its replaced with pvc then it isn't a metal underground water pipe any more. we were talking about underground metal water pipes?
If that isn't good enough I can show you a whole city of houses that for the last 50 years only have 1 ground rod, thats why they didnt put your exception in the code maybe

 

[electrofelon]

Um,...yeah when its replaced with pvc then it isn't a metal underground water pipe any more. we were talking about underground metal water pipes?
If that isn't good enough I can show you a whole city of houses that for the last 50 years only have 1 ground rod, thats why they didnt put your exception in the code maybe

The issue is we often don't know if the metal pipe has been replaced with plastic or has a dielectric union underground outside the foundation.

yes there may be a whole city set up with one supplemental rod, but it is not correct per NEC

 

[Electromatic]

I'm just saying that if you DO have a QUALIFYING water pipe at the time of installation, why does it need to be supplemented by two rods when any other rod or pipe only 8' long would need only one more rod?
I can understand, maybe, that the water pipe is more likely to get altered in the future than a ufer or structural metal, but it seems that is a "what if" case that the code doesn't otherwise (nor should) address in other areas.

 

[newservice]

I'm just saying that if you DO have a QUALIFYING water pipe at the time of installation, why does it need to be supplemented by two rods

it doesn't. Thats what Im saying. See my post with the code section "the following..if present"

 

[wwhitney]

I'm just saying that if you DO have a QUALIFYING water pipe at the time of installation, why does it need to be supplemented by two rods when any other rod or pipe only 8' long would need only one more rod?

As previously commented, an underground water pipe electrode (250.52(A)(1)) is not a "pipe" electrode (250.52(A)(5)). For example, 250.53(G) requires the latter to be driven to 8' of depth, which is deeper than most water lines. So it's not any "other" rod of pipe electrode, it's any rod or pipe electrode.

As to the reason, I infer it's because the plumber/homeowner who replaces the water pipe with plastic pipe may not be aware of the electrical code and know to drive another ground rod.

Cheers, Wayne

 

[wwhitney]

it doesn't.

It certainly does under the current NEC, see the sections cited.

Cheers, Wayne

 

[SomeRandomPerson]

Here in Upstate NY National Grid does not allow anything in that kind of meter socket aka residential overhead 200a, besides the service conductors. Mass isn't any different as far as I know as New England and Mass are the other Grid territory besides Upstate NY.
Your underground water pipe, and/or the supplemental ground rod system, would be all connected at the service disconnect, which is the first place inside the residence that the service entrance conductors terminate. The entrance cable must terminate in a disconnect within a short distance of entering the structure. (short distance which I am still unsure exactly how far but I like to keep it about 4 feet or less.)
Additionally, if you have municipal water, as your diagram indicates, you only need one supplemental ground rod. The water meter connection on the side that goes to the underground water pipe is considered a mandatory ground, then, if the inside water piping is metalic, you jumper across the water meter to Bond the inside water piping.

Thank you so much.
I’ll be up in Herkimer hunting this November. I have family in upstate. Thanks so much


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[Electromatic]

To the OP, @SomeRandomPerson
Best of wishes furthering your understanding of the trade. As you can see, the code, the occupation, and this forum can be approached from various angles of practice, comprehension, regionality, etc. -- all of which are subject to review triennially.

 

[infinity]

I'm just saying that if you DO have a QUALIFYING water pipe at the time of installation, why does it need to be supplemented by two rods when any other rod or pipe only 8' long would need only one more rod?
I can understand, maybe, that the water pipe is more likely to get altered in the future than a ufer or structural metal, but it seems that is a "what if" case that the code doesn't otherwise (nor should) address in other areas.

It needs to be supplemented by another electrode from the list in Article 250 because the metal pipe might get changed. That's the reason the supplementation requirement is in the NEC. Although not code this comment from the NECH is commonly used to explain why we supplement the water pipe electrode.

"The requirement to supplement the metal water pipe is based on the practice of using a plastic pipe for replacement when the original metal water pipe fails. This type of replacement leaves the system without a grounding electrode unless a supplemental electrode is provided."

 

[Electromatic]

Thanks for the Handbook context, @infinity , though I still scoff a bit at the supplement to the supplemental rod and the "what if in the future" basis of the requirement.

 

[SomeRandomPerson]

To the OP, @SomeRandomPerson
Best of wishes furthering your understanding of the trade. As you can see, the code, the occupation, and this forum can be approached from various angles of practice, comprehension, regionality, etc. -- all of which are subject to review triennially.

Thank you. Lots of opinions and discussions here.


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[infinity]

Thanks for the Handbook context, @infinity , though I still scoff a bit at the supplement to the supplemental rod and the "what if in the future" basis of the requirement.

I hear you. For the most part we argue here that "what ifs" shouldn't be part of the NEC but this what if certainly is.

 

[MattG0311]

Ok, so in the OPs case, could one just drive two ground rods, run to the meter main as the GEC, then bond the water pipe and run to the panel and tie to the ground bar as an EGC for the water piping? That said the only neutral to ground bonding occurs in the meter main. Run 4-wire to the panel. This way if anything changes down the line the GEC is the ground rods conveniently located at the meter main. Am I wrong? Just another crayon eating apprentice here...

 

[MattG0311]

Attached chicken scratch drawing:

 

[ptonsparky]

Attached chicken scratch drawing:

Depends.
The meter main being on/in the house: the GEC to the water pipe goes to the MM neutral bar which should be bonded to the enclosure. Rods as drawn, OK.

MM not on/in house: (For S&Gs say 50') Neutral bar in house isolated from EG, the water pipe and supplemental rods are connected to the EG bar.
GEC to rods at MM location. Water pipes not present at MM location so no bond needed.

 

[MattG0311]

So I can’t ground the water pipe with an EGC to the panel and maintain the GEC as ground rods terminated in the MM unless it’s not located on or in the house? The reason I ask is I have a similar set up with a MM attached outside the house and 4 wire running into the house main panel. (Main bonding jumper removed)
I don’t want to have to run the grounding conductor off the water piping inside through the main panel back to the MM; nor do I want to bore a new hole through the house just for a ground wire...
If I’m way out of left field with my thinking please let me know. I read through different GEC types yesterday and could not find any preference the NEC gives as to type. Essentially I want to choose ground rods over water piping out of convenience to my install, but I understand that ground resistance of the water pipe is very likely lower than two ground rods.
My thoughts are I still bond the water pipe to the panel so equipotential issue is satisfied, but I use ground rods as the GEC to save labor in punching through a thick brick wall or using my panel as a raceway.
Thanks for any input, any provided code references I’ll do my due diligence to read and interpret.

 

[wwhitney]

The meter main being on/in the house: the GEC to the water pipe goes to the MM neutral bar which should be bonded to the enclosure. Rods as drawn, OK.

Or if the EGC between the MM and the interior panel complies with 250.121 Exception, then it's fine as drawn.

Cheers Wayne

 

[SomeRandomPerson]

Attached chicken scratch drawing:

MVP!


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[Electromatic]

I'm curious now what everybody does when the water pipe entering the house is NOT a qualifying electrode. That is to say, you're just bonding the piping system. I've routinely run a bonding wire from a convenient spot on the piping to the inside panel even if that is technically a sub-panel with a main disconnect outside. Reading 250.104(A)(1) says to run it to the service or the GEC.

 

[wwhitney]

250.121 doesn't speak to bonding jumpers, so there's nothing wrong with using the EGC in the subpanel feeder as part of a series of bonding jumpers back to the service. I would think the EGC should be at least as big as the required bonding jumper size for this to work.

Cheers, Wayne