Jumping the water meter.

[ssarmoogam]

In NY at most residential and commercial job sites, at the water meter 2 water main clamps are placed left and right of the water meter and then jumped with wire. Can any one tell me why do you do that when there is already a ground applied close to the the water meter?

 

[stud696981]

Re: Jumping the water meter.

This is called a bonding jumper. It is installed so that if the water meter is ever removed for service the grounding path will remain. This became popular when PVC pipe started being used for replacement and the grounding electrode conductor was placed on the closest cold water pipe. Now the GEC must be run to the first 5 feet of the street side of the meter in most cases.

 

[George Stolz]

Re: Jumping the water meter.

See 250.53(D)(1).

Holy smokes I found something in 250. Stop the presses.

 

[electricmanscott]

Re: Jumping the water meter.

Originally posted by stud696981:
Now the GEC must be run to the first 5 feet of the street side of the meter in most cases.

The GEC does not need to be run to the "street side" of the meter.

 

[George Stolz]

Re: Jumping the water meter.

Originally posted by electricmanscott:

Originally posted by stud696981:
Now the GEC must be run to the first 5 feet of the street side of the meter in most cases.

The GEC does not need to be run to the "street side" of the meter.

250.52(A)(1) differs, Scott...? I know you're being clever, but I ain't seein' it.

 

[iwire]

Re: Jumping the water meter.

The words 'water meter' do not appear in 250.52(A)(1).

 

[tom baker]

Re: Jumping the water meter.

The NEC uses the term water meter:
(1) Continuity. Continuity of the grounding path or the bonding connection to interior piping shall not rely on water meters or filtering devices and similar equipment.
Keep in mind most applicaitons the water pipe is not metallic and does not meet the requirements to be a grounding electrode.

 

[George Stolz]

Re: Jumping the water meter.

Originally posted by iwire:
The words 'water meter' do not appear in 250.52(A)(1).

The water meter could be at the street, but that's usually better than 10' away from the house around here.

Question: Suppose the meter were 3.0' from the entrance to the house. In order to comply with the codes mentioned above, would I need to run the GEC to a point previous to the meter, bond there and continue with the unspliced GEC to the final destination less than 2.9' from entrance? Or can that water meter jumper always/never/sometimes be a seperate conductor that's sole function is to jumper across the meter?

I've always run it unspliced to do both jobs with #6, but with the 4/0 aluminum I'd like to get away from that. Something about exposing the aluminum for an inch midstream makes me uneasy...

 

[iwire]

Re: Jumping the water meter.

George the requirement for a continuous conductor only applies to the GEC, not bonding jumpers.

You could run a GEC from the panel to 1' from the entrance of the water pipe. Now that is the end of the GEC.

Take a separate conductor and jump the water meter.

Take another separate conductor from the water pipe and run it to the ground rod.

Take another separate conductor from the water pipe and run it to a concrete encased electrode.

All these separate conductors are bonding jumpers, they are not GECs.

A picture will help.



[ December 24, 2004, 10:27 AM: Message edited by: iwire ]

 

[George Stolz]

Re: Jumping the water meter.

Thanks, Bob, good picture. But it is missing the supplemental GEC, isn't it? Doesn't that have to go to the service?

The size of the GEC is determined by 250.66, but what determines the size of all the jumpers? Can you cite a code reference?

I would love to walk away from this knowing grounding a whole lot better!

 

[George Stolz]

Re: Jumping the water meter.

The water meter could be 1' from the point of entrance to the building, I could still connect my GEC at 5' from the point of entrance to the building.

That being the case, that particular jumper would need to be as large as the GEC, right?

 

[iwire]

Re: Jumping the water meter.

Good Morning George I had to step out and get some stocking stuffers.

Originally posted by georgestolz:
But it is missing the supplemental GEC, isn't it?

There is no such thing as a supplemental GEC.

There is a requirement for a Supplemental Electrode. 250.53(D)(2)

The only time this requirement is an issue is when the water pipe is the only electrode available.

If the water pipe is the only available electrode you must install a Supplemental Electrode, however nothing says that has to be a rod, it could be any type of electrode.

Originally posted by georgestolz:
Doesn't that have to go to the service?

If you are asking about the conductor running to the Supplemental Electrode no, it does not have to go to the panel it can go to the panel or to an other part of the grounding electrode system.

Originally posted by georgestolz:
The size of the GEC is determined by 250.66, but what determines the size of all the jumpers? Can you cite a code reference?

250.53(C) tells us how to install the bonding jumpers per 250.64(A) and size them per 250.66.

Now 250.66 tells us how to size GEC and the bonding jumpers to Table 250.66 but.....

250.53(E) tells us no mater what the bonding jumper to Supplemental Electrode is a rod, pipe, or plate electrode the bonding jumper does not have to be larger than 6 CU or 4 AL AWG.

250.66(A) tells us Rod, Pipe, or Plate Electrodes only need 6 CU or 4 AL AWG.

250.66(B) tells us Concrete-Encased Electrodes only need 4 CU

250.66(C) tells us Ground Rings do not need conductors larger than the ring itself.

I will be installing a 600 amp 480 volt temporary service next week, I have not seen the site yet but it is very likely all I will have is two ground rods as my grounding electrodes, the GEC from the 600 amp disconnect to the ground rods will only be 6 AWG.

I could just put one ground rod in if I could prove 25 ohms or less resistance but it is just easer to install a second rod. Check out 250.56 for this requirement.

I have not decided what I will be running to the service probably 3 runs of 4/0 AL. That being the case if a water pipe is available that conductor would need to be 1/0 CU.

[ December 24, 2004, 11:52 AM: Message edited by: iwire ]

 

[electricmanscott]

Re: Jumping the water meter.

What he said.

 

[websparky]

Re: Jumping the water meter.

Nice job Bob

 

[George Stolz]

Re: Jumping the water meter.

That has cleared a lot up for me, thanks bigtime!

The water meter could be 1' from the point of entrance to the building, I could still connect my GEC at 5' from the point of entrance to the building.

That being the case, that particular jumper would need to be as large as the GEC, right?

That still puzzles me. Since that jumper is for the GEC, it needs to be the size of the GEC, right?

 

[iwire]

Re: Jumping the water meter.

Yes the grounding electrode bonding jumpers are sized the same as grounding electrode conductors.

By the way George their is nothing wrong with doing it like you describe. This is an area of the NEC that leaves us options on how we prefer to do it.

We can leave the panel once and daisy chain to each electrode or we can leave the panel separately to each electrode.

It's nice to have options.

 

[George Stolz]

Re: Jumping the water meter.

Thanks for all that. I'm trying to make the leap from trained monkey to actually understanding grounding. 250 is kind of a repetitive, confusing chapter for me.

Thanks again.

 

[iwire]

Re: Jumping the water meter.

George 250 is tough no question about it.

All of a sudden it will start to make sense.

Some of the reasons for so many sections is to allow us options.

Bob