multiple units one service multiple water pipes

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e2me2

e2me2

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South Dakota
I have a steel building devided into 4 units each with its own service and water service. The panels are all feed with 4/0 ser from a 4 stack meter having breaker disconnect inside it for each 200.I drove a ground rod and ran a 2/0 alum to water service 1 as per 250.66 for a 640amp cal load but what the hell do i run to other water services.

are they supplimental 250.66A ,250.53E #6 from each bay panel to its own water supply

are they each there own water pipe and need a 2/0 to each from meter stack ( not enough lugs)

are the falling under 250.104-2 in which case it would be a #4 to each pipe from the panel in that unit. but there are all metel pipes in each they are not connected as i did a ohm check. so outside somewere there is plastic or other

help please
 
These would be 250.104. Take a look at (A)(2), which will allow you to go to each unit's panelboards instead of having to go all the way back to the service. The bonding jumpers will be sized based on the rating of the breaker feeding the unit (although the 2005 doesn't say that, my proposal to clarify it in the 2008 is passing at this point).

By the way, your 2/0 Al GEC is undersized.
 
ryan_618 said:
These would be 250.104. Take a look at (A)(2), which will allow you to go to each unit's panelboards instead of having to go all the way back to the service. The bonding jumpers will be sized based on the rating of the breaker feeding the unit (although the 2005 doesn't say that, my proposal to clarify it in the 2008 is passing at this point).

By the way, your 2/0 Al GEC is undersized.
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I was leaning this way but was worried because of the metel pipeing not plastic as states in the code

my 2/0 is sized for parralel 500 mcm which is what the power company brought to the meter 250.66 1000 cml 2/0 copper sorry
 
e2me2 said:
I was leaning this way but was worried because of the metel pipeing not plastic as states in the code
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If they are not connected, they are isolated.

If they are isolated, they need bonding.

If they are not isolated, then they are interior water pipes bonded by the GEC.

Why did the utility install parallel 500's for a 640-amp connected load? Also, your GEC appears appropriately sized...?
 
Isn't the OP asking in part if the 4 individual underground metal water pipes need to be bonded together as part of the grounding electrode system?

Base on 250.50, I'd say yes: 250.50 Grounding Electrode System
All grounding electrodes as described in 250.52(A)(1) through (A)(6) that are present at each building or structure served shall be bonded together to form the grounding electrode system.
 
John, I agree with you that the code does read all that are present. I had a lengthy discussion with a few different members of panel 5 about this very item, and they all tend to agree that you must use an electrode thta meets 250.52(A)(1), and after that you have satisfied the requirement of grounding to a water pipe. Everything after that would be bonding to prevent them from becoming energized.

e2: I would imagine the utility provided you a service lateral, not service entrance conductors. With that said, you would have to follow note 2 to Table 250.66, which would require you to go off of the calcultaed load, and assign a conductor from 310.16 (large enough for the load) to inserst into Table 250.66. 2/0 Al would only be good for a 350 copper service entrance conductor, which would not carry the calculated load that you have.
 
ryan_618 said:
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e2: I would imagine the utility provided you a service lateral, not service entrance conductors. With that said, you would have to follow note 2 to Table 250.66, which would require you to go off of the calcultaed load, and assign a conductor from 310.16 (large enough for the load) to inserst into Table 250.66. 2/0 Al would only be good for a 350 copper service entrance conductor, which would not carry the calculated load that you have.
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He restated in P#3 the 2/0 is CU.
 
ryan_618 said:
John, I agree with you that the code does read all that are present. I had a lengthy discussion with a few different members of panel 5 about this very item, and they all tend to agree that you must use an electrode thta meets 250.52(A)(1), and after that you have satisfied the requirement of grounding to a water pipe. Everything after that would be bonding to prevent them from becoming energized.
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That does make sense. Similar to multiple sets of rebar which are not all tied together. Such as footing rebar not always tied to foundation rebar. Nobody's hitting every individual section of rebar in a foundation.

Thanks, Ryan
 
j_erickson said:
That does make sense. Similar to multiple sets of rebar which are not all tied together. Such as footing rebar not always tied to foundation rebar. Nobody's hitting every individual section of rebar in a foundation.

Thanks, Ryan
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John, CMP 5 has actually accepted a proposal (Proposal 5-137) to recognize that fact. :cool:

Panel Meeting Action: Accept in Principle
Add a new senternce to Section 250.52(A)(3) to read as follows:
Where multiple concrete-encased electrodes are present at a building or structure, it shall be permissible to bond only one into the grounding electrode system.
Panel Statement: The panel concludes that the requirements for the concrete encased electrode belong in 250.52(A)(3) and that 250.50 should only contain the requirements to establish a grounding electrode or grounding electrode system.

Number Eligible to Vote: 15
Ballot Results: Affirmative: 14 Negative: 1
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j_erickson said:
Does make me wonder who would vote no to that and why!
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I figured it would. I like to tease, which is why I left it off. :)

Explanation of Negative:
BRENDER, D.: The proposal would have the effect of permitting multiple, independent electrodes to be present without bonding in between. This would allow the earth to serve as a current-carrying conductor during lightning or similar transient conditions.
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While I partially see the merit in the first sentence, I think he didn't quite think it through when he wrote the second sentence. I believe the earth carrying current in the event of the lightning strike is sort of the goal of grounding, wouldn't you say? ;)
 
Yea, I'd say.

Did you really have the presence of mind to purposefully leave off the explanation of negative?

You must want to make sure I'm paying attention.;)
 
While I partially see the merit in the first sentence, I think he didn't quite think it through when he wrote the second sentence. I believe the earth carrying current in the event of the lightning strike is sort of the goal of grounding, wouldn't you say? ;)[/QUOTE]


George
What he may have been thinking of, the lightning traveling through earth from one electrode to another, creating a path that may not be desirable.
 
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