Grounding multiple service enclosures

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eddycurrents

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Hello all. I had some questions to ask about a service I installed on a 12 unit apartment complex. I installed 2 - 6 gang meter bases, with built in disconnects, to feed power to each apt. I have two service risers that the poco will connect 1 service drop to. When it came time to ground the 2 meter bases I followed 250.64(D). Each service riser had a 350 kcmil ungrounded conductor so I ran a 2/0 copper wire to the cold water ground. (350 + 350 = 700 kcmil, table 250.66). I landed the 2/0 to 1 meter base and dropped out of the 2nd with a #2 which I used a split bolt to connect to the cold water grounding electrode. There is a picture on page 201 of the NEC handbook that shows exactlly what I did. Plus the Soares Book on Grounding says I can use a split bolt for my connection on page 103. I then drove 1 ground rod which I ran a #6 from this and used a split bolt to connect it to the 2/0 cold water ground. Was this the correct way to ground these two meter bases? The inspector turned it down. He said that (1)you can NEVER use a split bolt on any grounding electrode conductor, tap or not. (2) I needed to treat each meter pak as its own service (3) I need to run a seperate cold water ground for each service, and (4) I need to drive a seperate ground rod for each meter pak. Does any of this sound correct? Thanks for any replies.
 
Re: Grounding multiple service enclosures

Sounds to me like the inspector is wrong on this one. Did you show him your reference material?
 
Re: Grounding multiple service enclosures

Hello Pierre, there are not any disconnects ahead of the meter paks. The sevice wires enter the meter paks where they land on 3 busses. The 3 busses are connected to 6 meter sockets. From the load side of each meter socket a 100 amp breaker is installed to protect the feeder wires going into each apartment. I installed the grounding system the way the inspector wanted it done allthough I think he was wrong. It cost me 2 labor hours and $40 in material so I guess I cant complain to much. I mainly asked the question for my own peice of mind. I dont argue with inspectors anymore as I have never had 1 say to me " you know, your right and I was wrong, please do it your way." :D
 
Re: Grounding multiple service enclosures

With a seperate gnd rod for each meter pack, that created 2 available rod electrodes "on site" and the code would require them to be tied together (along with the water) to form the GES.

I'd agree the inspector was wrong here. Water, rod(s) and GES taps should have been OK.
 
Re: Grounding multiple service enclosures

Eddycurrents
I have a couple of more questions:
Are the meter banks outside the building?
Are there fire rated walls between each apartment?
How close is each meterbank to each other?

Pierre
 
Re: Grounding multiple service enclosures

You have two separate service enclosures being tied to the power company. Two risers, two services. Each meter pak has to be set up separately. You must run a separate grounding system to each meter pak. The split bolt cannot be used seeing that article 250.62(c) states that the grounding electrode shall be installed in one continuous length without a splice unless done so by a unreversible method like compression or welding. A number six is to small for a ground conductor. The bonding conductor is to be sized according to 250.66 and the grounding conductor is sized according to the same table. The ground wire and bond wire would be required to be #2.
 
Re: Grounding multiple service enclosures

dpoland
You realy need to read 250.58 Common Grounding Electrode. As it clearly states:
Where separate services supply a building and are required to be connected to a grounding electrode, the same grounding electrode shall be used.
Click to expand...
And as far as the #6 GEC Look at 250.53(E)
And as for the taps look at 250.53(D)(2) Then look at 250.54
And you should see where his installation was code compliant
 
Re: Grounding multiple service enclosures

Hurk27
Sorry I did not comment on the two ground rods. The articles you refer to are for suplemental grounding and bonding. The wire going to the water pipe is a bond not a ground wire. The wire going to the ground rod is your ground. The reason for this is that on new buildings most areas of the country no longer have 10' of metal water pipe being brought into the building. Most all water pipe in new buildings are plastic now. Building steel would be supplemental and can be run with a #6 and be tapped. Primary ground and bond must be continuous.

[ January 15, 2004, 08:27 AM: Message edited by: dpoland ]
 
Re: Grounding multiple service enclosures

Eddycurrent clearly states he is using the cold water as one of his grounding electrodes.
He has two service risers connected to one service drop - this makes it one service to the building.
250.64 applies as the taps to more than one enclosure of the same service.This section does not require an irreversible connection, making a split bolt permissible.

My question is how many disconnects does he have?
One disconnect to each meterbank? Making that a total of two, or... two meterbanks with six disconnects making a total of twelve?

Do the load side risers run inside the building or outside the building?

Pierre

[ January 15, 2004, 01:21 PM: Message edited by: pierre ]
 
Re: Grounding multiple service enclosures

Originally posted by dpoland:
The wire going to the ground rod is your ground. ......... Building steel would be supplemental and can be run with a #6 and be tapped. Primary ground and bond must be continuous.
Click to expand...
dpoland no matter what you want to call it the GEC to a any ground rod is not required to be larger than 6 AWG by the NEC.

IF you do a temp 400 amp service and there are no electrodes available 6 AWG to a driven rod(s) is all that is required. :)

Take a look at 250.66(A)
 
Re: Grounding multiple service enclosures

Originally posted by dpoland:
Building steel would be supplemental and can be run with a #6 and be tapped. Primary ground and bond must be continuous. [/QB]
Click to expand...
Two things: Number one, the term "primary" refers to transformers, not grounding electrode systems. Number two: The building steel can indeed be used as a supplement, howver it still must be sized off of 250.66. Supplement electrodes are discussed in 250.53(D)(2) and nowhere does it say that the grounding electrode conductor for the supplement need not be larger tahn number six. That is addressed in 250.66(A) and does not apply.
 
Re: Grounding multiple service enclosures

Pierre, I have 12 disconnects. The inspector said I didnt need a disconnect ahead of each meter pack. The load side risers are run along the outside of the building, into the attic, and down to the apartments panel.

[ January 15, 2004, 10:58 PM: Message edited by: eddycurrents ]
 
Re: Grounding multiple service enclosures

First off do we agree that with the two risers and the two meter paks not being connected together there are two separate services according to 250.24? This means that 250.64(D) does not apply to this installation I am sorry if you did not understand what I was trying to say.
 
Re: Grounding multiple service enclosures

Eddy:
?I have two service risers that the poco will connect 1 service drop to?

As soon as you say One service drop you have one utility supply you have one service. The wording of 230.2 Number of Services. Is the only time that I know of that you can have more than one utility supply and still be considered to have one service

?For the purpose of 230.40, Exception No. 2 only, (only, underground sets of conductors, 1/0 AWG and larger, running to the same location and connected together at their supply end but not connected together at their load end shall be considered to be supplying one service.)?

?230.40 Number of Service-Entrance Conductor Sets. Each service drop or lateral shall supply only one set of service-entrance conductors. Exception No. 2: Where two to six service disconnecting means in separate enclosures are grouped at one location and supply separate loads from one service drop or lateral, one set of service-entrance conductors shall be permitted to supply each or several such service equipment enclosures.?

So you have to have more than one supply to a structure before it can be defined as more than one service You can still consider a structure served by more than one service lateral sized 1/0 or larger grouped at one location and no more than six service disconnect one service.

Eddy I do not se any thing in your post that could be used to define what you have as two services. What you have is one service and two sets of service entrances. The problem is from what you posted you have 12 disconnects grouped at one location feed from one utility supply. You can never group more six service disconnects at one location.

When you look at the handbook Exhibit 230.4 you can see it an inspectors call to decide how far a group of service disconnects have to be apart to determine that they are at two separate locations

[ January 17, 2004, 03:18 PM: Message edited by: david ]
 
Re: Grounding multiple service enclosures

Originally posted by david:

The problem is from what you posted you have 12 disconnects grouped at one location feed from one utility supply. You can never group more six service disconnects at one location.
Click to expand...
Well dont say never. As we speak I have 12 disconnects fed from 1 service, that passed inspection, and have allready been connected to the the utilitys XFMR. :eek:
 
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