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#208256 - 01/05/13 08:51 PM 400 amp four gang meter question..  
njelectrician  Offline
New Member
Joined: Jan 2013
Posts: 3
New Jersey
Hello all. I have to price out a 400 amp service for a condominium. The Buildings have a 4 gang meter bank with four seperate 150 amp mains. Each main feeds a 30 circuit main lug panel in each apartment. (4 apartments, no house meters) Each apartment has its own water meter inside each dwelling. My thought is that I have to run a seperate egc sized for 400 amp to each water meter in each unit. Is this correct?


2017 / 2014 NEC & Related Books and Study Guides

#208257 - 01/05/13 09:21 PM Re: 400 amp four gang meter question.. [Re: njelectrician]  
HotLine1  Offline


Member
Joined: Apr 2002
Posts: 6,872
Brick, NJ USA
Welcome to ECN forums from one of the 'Jersey Guys'!!

Your GEC is at the service neutral buss. Each apt has 150 amp feeder (4 wire) with the EGC sized to 150 amp OCP.

Now, is the water service to the structure metalic, or plastic? Is the water piping within each unit metalic or plastic?

You would be bonding the metalic water piping in each unit, with a EGC (bond) from the panel to the piping based on the OCP of the panel (150 amp), and a jumper at the water heater H&C, if metalic.

Are you north jersey or south jersey??


John

#208262 - 01/06/13 08:20 AM Re: 400 amp four gang meter question.. [Re: njelectrician]  
Tesla  Offline
Member
Joined: Jun 2004
Posts: 1,273
Sacramento, CA
Your OP has me confused.

Is this a (2) leg 1-phase 400A/240 VAC Service that is split out just in front of the (4) OCPD?

Is this a 3-phase Service that feeds 5-jaw meters in a stack?

BTW, bonding to the water system... Is it an old metallic system?

Is it new construction?

Is Grandfathering at issue?

Are the apartments using Insta-Hots? ( Tax breaks exist in some areas for these -- in California we're seeing a lot more of them. )

Do you have to provide a Low Voltage/ Data junction bar for each abode?

Is this really just a fourplex? A rewire?

Flood damaged property?

Federally reimbursed/ assisted?

Does it consequentially have waivers/ stippulations?

------------

^^^^^ Would be much more important in composing a realistic bid than concern about running, say #4 THHN a dozen feet to a Water Service Entrance Pipe.



Tesla

#208266 - 01/06/13 02:53 PM Re: 400 amp four gang meter question.. [Re: njelectrician]  
njelectrician  Offline
New Member
Joined: Jan 2013
Posts: 3
New Jersey
Its a condo that was built a few years ago and abandoned. I am still gathering info, but from what I can see the finished units have 400 amp single phase services to a 4 gang meter bank on one side of the building. The units are laid out horizontal and each SER run goes through each unit to the unit its feeding. So far it appears each unit has copper water feeds from the street. I dont know if the rebar was bonded. not flooded and not a rewire. These units are in frame. I have others to pick up that are in different phases of construction. I am not yet sure about data junction bar yet, i am waiting to talk to someone in the know. The contractor has not given me any plans or specs yet. Right now i am trying to price out what i can see.


#208268 - 01/06/13 03:55 PM Re: 400 amp four gang meter question.. [Re: njelectrician]  
Scott35  Offline

Broom Pusher and
Member
Joined: Oct 2000
Posts: 2,708
Anaheim, CA. USA
Hola njelectrician!

The basic Quick and Dirty descriptions are:

For the 150 Amp Panelboard Feeders (Tenant Feeders):

(1) #6 CU. EGC (Copper, Equipment Grounding Conductor) from the Service Section, to the 30 Space Panelboards at the Tenant Spaces.
Each of the (4) Panelboard Feeders would comprise of:
(2) 1/0 THHN Cu. Ungrounded Conductors,
(1) 1/0 THHN Cu. Grounded Conductor,
(1) #6 Cu. Equipment Grounding Conductor.

For the 400 Amp Service (Main Service Equipment):

1-A: If the Service Feeder's Largest _UNGROUNDED CONDUCTOR_ size equals:
a1. 4/0 Cu. to 350 MCM Cu.
or;
a2. 300 MCM Al. to 500 MCM Al.,

Minimum/Maximum size Grounding Electrode Conductor would be #2 Cu.

1-B: If the Service Feeder's Largest _UNGROUNDED CONDUCTOR_ size equals:
b1. 400 MCM Cu. to 600 MCM Cu.
or;
b2. 600 MCM Al. to 900 MCM Al.,

Minimum/Maximum size Grounding Electrode Conductor would be #1/0 Cu.


In either case (1-A or 1-B), only (1) GEC needs to be run from the Service Equipment to the Cold Water Grounding Electrode, Terminated </= 5 Feet from where the Cold Water enters the Building from the "Street".

The Cold Water Electrode will require a Supplementary Electrode, which may be any of the qualifying types listed in Article 250.
Common Supplement Electrodes are:
* Driven Ground Rod(s),
* Concrete-Encased Electrodes ("Ufer")

Min/Max GEC size for Driven Rods: (1) #6 Cu.
Min/Max GEC size for Concrete-Encased Electrodes: (1) #4 Cu.


*** NOTE ***
Aluminum Grounding Electrode Conductors not listed, due to nearly 100% of the DBS's have amended NEC Article 250 to read:
"Grounding Electrode System Conductors To Be Copper Only"
(I include the above text in the "City/County DBS Specific Notes" Database on all Plan Sets).

--Scott (EE)


Scott " 35 " Thompson
Just Say NO To Green Eggs And Ham!

#208273 - 01/07/13 03:09 AM Re: 400 amp four gang meter question.. [Re: njelectrician]  
njelectrician  Offline
New Member
Joined: Jan 2013
Posts: 3
New Jersey
Thanks everyone for the replies. Scott, So I only need to run one GEC even though each unit's water pipe is directly fed from the street? if so, there would be ungrounded water meters in 3 of the four units. Each unit has its own water meter and copper pipe feed from the street in its own basement.


#208301 - 01/09/13 11:45 PM Re: 400 amp four gang meter question.. [Re: njelectrician]  
harold endean  Offline
Member
Joined: Feb 2002
Posts: 2,233
Boonton, NJ
Is there a sub panel in each area? Can you run a ground wire from the sub panel to each water line in each area?


#208318 - 01/11/13 05:15 AM Re: 400 amp four gang meter question.. [Re: njelectrician]  
Scott35  Offline

Broom Pusher and
Member
Joined: Oct 2000
Posts: 2,708
Anaheim, CA. USA
NJ;

Quote

So I only need to run one GEC even though each unit's water pipe is directly fed from the street?


Yes, only One GEC is needed to Bond the Service Equipment to the Cold Water Grounding Electrode.
At least (1) additional Electrode will be required to supplement the Cold Water Electrode.

Quote

if so, there would be ungrounded water meters in 3 of the four units.


We are using the Cold Water line(s) as an Electrode, which in itself is a Grounded entity.
The City Cold Water piping _SHOULD_ be commonly connected on the "Street" side of the Water Meters.


Quote

Each unit has its own water meter and copper pipe feed from the street in its own basement.


Your AHJ might request that you to Bond all of the Cold Water lines together via a Copper Conductor, so as to create a Single Electrode.
This may be accomplished in several ways;
a. Bonding all Water Pipes together, using a Single Conductor,
b. Jumpers around all Water Meters,
c. Bond each Tenant's Cold Water line to the EGC from each Panelboard Feeder,
d. Reference Article 250 for other approved Bonding methods.

--Scott (EE)


Scott " 35 " Thompson
Just Say NO To Green Eggs And Ham!

#208319 - 01/11/13 02:19 PM Re: 400 amp four gang meter question.. [Re: njelectrician]  
gfretwell  Offline


Member
Joined: Jul 2004
Posts: 9,123
Estero,Fl,usa
Just don't forget what John said about bonding the water pipe in each unit. This is a bond, not a ground electrode. I know the electrons don't know the difference but you can use smaller wire per 250.104(A)(2). That will be #8 for a 150a feeder supplied unit instead of the 1/0 you probably end up with on the service side from 250.66.


Greg Fretwell

#208338 - 01/12/13 01:05 PM Re: 400 amp four gang meter question.. [Re: njelectrician]  
HotLine1  Offline


Member
Joined: Apr 2002
Posts: 6,872
Brick, NJ USA
Thanks Greg. Yes, the water piping bond within each unit should have a jumper over each water meter (bond). Most of the new construction here is some form of non-metalic water lines; PEX, hard PVC, etc. And yes, there are still a few of the guys that put a bond at the water meters effectively bonding the non-metalic! Old habits die hard.

I was/am curious as to what part of NJ the OP is in. IMHO, the majority of the water lines are PVC, with an occasional copper (soft) unrolled into a trench.

BTW, the same guys that still bond the water meter, still bond the water heater H-C in PEX houses!

Hey NJElectrician: Do these units have a natural gas supply with CSST?? If they do, the gas piping must be bonded to the GEC at the point of entry. Check your local AHJ!!


John

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