When using multiple Electrodes does order Matter?

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David40

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When connecting to multiple Grounding Electrodes, (ie. ground rod and water pipe), does it matter what order they are connected in? From the service is there a requirement that it should hit the rod or the water pipe first?
(I should note, is this jurisdiction a ground rod is required regardless of any other electrodes.)
For example, say you have an outdoor meter can located about 10" away from the closest pipe that is part of an interior water system. Would it be best to drive the rod directly under the meter can and run the Grounding Electrode Conductor to the rod and then over to the water pipe, or would it be better to run 10' over to the water pipe first and then drive the rod there and connect the GEC below it?
Because of the high frequency of lightening here I tend to prefer driving a ground rod right under the meter can to give the surge a short path to earth, but what do the experts say?
I appreciate the input.
 

roger

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Is there at least 10' of metalic water pipe in contact with the earth?

An interior water system is not a GE by itself.

Roger
 

David40

Member
Yes, I'm certain it is.

My intention is to bond the water system, not to use it as an electrode. Also, I should mention that there are at least two water pipes entering the building on opposite sides and each of those is longer than 10' in the ground.
 
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augie47

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It makes little difference as long as all are connected, but a few specifics can make a difference. You mention your water pipe and, if it qualifies as an electrode, you must connect to it within 5 ft after it's entry to the structure (see 250.52). That conductor must be sized per 250.66
You also mention you ground rod, note that 250.66(B) only requires that G-E conductor only be a #6.
So, if your water needs a #4, or #2 or whatever 250.66 requires and you routed to your rod first you would need that larger conductor. If you go to the rod independently it can be a #6 thus saving copper (and $$).

In regard to your added edit..you have no choice in using it as an electrode. 250.50 states that ANY and ALL electrodes present must be used. If your water pipe qualifies (10 ft or more in the earth) you must use it as an electrode and connect within 5 ft.
 
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roger

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Along with Augie's post, I would suggest you read all of 250.52 for the electrodes that must be used if present.

Roger
 

David40

Member
So, if I understand you, I would need to run my 1/0 CU whatever distance necessary to pick up that water pipe 50" away on the opposite side of the building?
This raises other questions. Is the water considered a part of the pipe? Obviously if the pipe was PVC it's not a conductor, but the water is. (Even thought pure water is an insulator, normal (contaminated) water is a great conductor) For example, say the building water pipes are all plastic, but where the pipe connects to the city supply at the street 50" away it turns to metal. Technically I can say for a fact, that the water in that pipe is as good a conductor as if the entire pipe was metal. So why wouldn't all water pipes regardless of what they are made of, be considered an electrode?
Anyway, under the current rules would this "work around" be acceptable? Because of the cost would I be better off cutting a small section out of that metal water pipe and installing a $10 dollar PVC compression fitting to isolate it, and making it not and electrode?
 

tryinghard

Senior Member
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California
Your really could add the PVC fitting, it's all about the metallic water pipe as qualified. If there are multiple qualified water pipes they must be used as electrodes, the actual water has nothing to do with it.
 

David40

Member
The funny thing about this is that the entire water system itself is an electrode because of the type of construction. We have a monolithic slab where all the water and electrical piping is mostly running under the slab in the ground virtually making the entire building an electrode.
To follow the code to the letter in this case would require a 1/0 CU wire to every point where a water line poked up through the slab to pick up a sink or toilet. I can see where you could easily go mad thinking about this topic. :)
 

roger

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The funny thing about this is that the entire water system itself is an electrode because of the type of construction. We have a monolithic slab where all the water and electrical piping is mostly running under the slab in the ground virtually making the entire building an electrode.
To follow the code to the letter in this case would require a 1/0 CU wire to every point where a water line poked up through the slab to pick up a sink or toilet. I can see where you could easily go mad thinking about this topic. :)

Have you read the article sections we have given you, 250.52(A)(1) in particular.

This sounds like new constrution so is there rebar in the footer?

Roger
 

David40

Member
Yes I have, and it gave a huge headache, I ran out of fingers to hold all the reference points. I think it would be easier to appoint a grounding guru who people could ask a grounding question and his answer would be the final word. Why should everyone have to reinvent the wheel every time. :)

Actually it's very old (1950) mostly galvanized pipe for water and electric.
 

augie47

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Tennessee
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State Electrical Inspector (Retired)
Yes I have, and it gave a huge headache, I ran out of fingers to hold all the reference points. I think it would be easier to appoint a grounding guru who people could ask a grounding question and his answer would be the final word. Why should everyone have to reinvent the wheel every time. :)

Actually it's very old (1950) mostly galvanized pipe for water and electric.

That guru is you local electrical inspector :)
I think most inspectors would look at what you have as a "system" and once you connected at the entrance there would be no need to connect to each point where the piping penetrates the slab.
For most of us it's somewhat of a checklist as identifying which electrodes are present (building steel, underground water, CEE, rods, etc) and then make sure each is connected per Code.
With occasional exceptions it's pretty cut and dry.
 

LarryFine

Master Electrician Electric Contractor Richmond VA
Location
Henrico County, VA
Occupation
Electrical Contractor
If your water pipe qualifies (10 ft or more in the earth) you must use it as an electrode and connect within 5 ft.
Makes me wonder: If I want to use an existing pipe as an electrode, I have to prove the 10' in the ground.

Upon whom is the burden of proof whether a pipe qualifies if I would rather it didn't for whatever reason?
 

tryinghard

Senior Member
Location
California
The funny thing about this is that the entire water system itself is an electrode because of the type of construction. We have a monolithic slab where all the water and electrical piping is mostly running under the slab in the ground virtually making the entire building an electrode.
To follow the code to the letter in this case would require a 1/0 CU wire to every point where a water line poked up through the slab to pick up a sink or toilet. I can see where you could easily go mad thinking about this topic. :)

Is it normal and actually your case that "every point where water line poke up through the slab" actually include metal underground water pipe in direct contact with the earth for >=10'; then breaks with non-metalic to the next point (at every location - as fact)?

If the underground water pipe qualifies with 250.52(A)(1) and remains metalic throughout you only have one water pipe electrode.

Don't forget the purpose of the electrode (250.4(A)(1))
 
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