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Grounding/Bonding side by side services #45592
12/02/04 11:15 PM
12/02/04 11:15 PM
B
BigB  Offline OP
Member
Joined: Mar 2004
Posts: 721
Tucson, AZ USA
Due to the high cost of dual meter packs I would like to use two side by side 100 amp meter combos for a two family complex. The dwellings are separate buildings, the service is overhead, and it is not feasable to put a service on each building. Both services will be on one dwelling, with an underground feed to a subpanel at the second dwelling.
To anyone who has done this, how did you set up the grounding electrode system. Will I need 2 rods for each service? I am thinking I can leave panel 1 with my GEC, hit the water and gas, hit the two rods then back up into panel 2.

Work Gear for Electricians and the Trades
Re: Grounding/Bonding side by side services #45593
12/03/04 10:10 PM
12/03/04 10:10 PM
S
shortcircuit  Offline
Member
Joined: Jun 2004
Posts: 608
massachusetts
Your method of grounding will be code compliant.If you decide to use the metal underground water pipe for your electrode,250.52(A)(1)says there must be 10 feet or more of metal water pipe in direct contact with the earth. You must supplement the metal water pipe with an additional electrode specified in 250.52(A)(2) thru (A)(7), according to 250.53(D)(2)

If you select a rod,pipe,or plate eletrode then you must comply with 250.56 which states that you need 25 ohms or less or add a 2nd electrode.

You do not need 4 electrodes for one service drop to a building.See exsample exhibit 250.28 on page 201 of the 2002 NEC handbook.Although the exhibit is misleading in the picture as it shows the #2 GEC just ending without terminating at the service equipments grounded conductor as required by 250.24(A)(1)

shortcircuit

Re: Grounding/Bonding side by side services #45594
12/04/04 04:52 AM
12/04/04 04:52 AM
E
e57  Offline
Member
Joined: May 2003
Posts: 2,876
S.F.,CA USA
Yuo should probhably give the inspector a call on this one....... It is after all his/her call on this one. They might require one on each for the possible lot split. I however would use a 2-pack, or a main disconnect to gutter and 2 panels, and ground from the main, and a single riser. (Were you going to run 2 risers, one for each? The "high cost" of dual meter packs would be negated by not having to install two panels.)

shortcircuit, many local areas the AHJ may require more electrodes and bonding than the NEC requires. I too am required to hit two rods (or a ufa)and water and gas to the main, bond the water (Hot / cold). Its not NEC minimums, but it is a way of life. [Linked Image]


Mark Heller
"Well - I oughta....." -Jackie Gleason
Re: Grounding/Bonding side by side services #45595
12/04/04 07:12 AM
12/04/04 07:12 AM
E
earlydean  Offline
Member
Joined: Dec 2003
Posts: 751
Griswold, CT, USA
You still need ground rods at the second building. See 250.32


Earl
Re: Grounding/Bonding side by side services #45596
12/04/04 08:12 AM
12/04/04 08:12 AM
S
shortcircuit  Offline
Member
Joined: Jun 2004
Posts: 608
massachusetts
Opps...my error...missed the seperate building part.I was thinking adjoined 2-family.

shortcircuit

Re: Grounding/Bonding side by side services #45597
12/04/04 08:33 AM
12/04/04 08:33 AM
S
shortcircuit  Offline
Member
Joined: Jun 2004
Posts: 608
massachusetts
So then, BigB will also need a disconnect at the seperate building and it must be suitable as service equipment.And also a grounding electrode at the 2nd building as earlydean pointed out.

How about the water pipe though...is there a water line between the dwellings?

shortcircuit

Re: Grounding/Bonding side by side services #45598
12/04/04 03:18 PM
12/04/04 03:18 PM
S
sandsnow  Offline
Member
Joined: Sep 2004
Posts: 167
Irvine, CA, USA
There are access issues first. Each occupant needs access to his or her service disconnecting means. On some ones elses property will not cut it. Occupant one could fence out ocupant two.
My first response would be no, and then carefully read all the code.
Maybe an easement could be drawn up....Up to the AHJ


Larry LeVoir
Inspector
City of Irvine, CA
Re: Grounding/Bonding side by side services #45599
12/04/04 03:28 PM
12/04/04 03:28 PM
I
iwire  Offline
Moderator
Joined: Jan 2003
Posts: 4,391
North Attleboro, MA USA
Sandsnow I can not find a requirement that Each occupant needs access to his or her service disconnecting means for this installation.

230.72(C) does not apply as this is not a multi occupancy building.

This is two separate structures, I think the disconnect required by 225.31 at the second structure should meet the NEC requirements.


Bob Badger
Construction & Maintenance Electrician
Massachusetts
Re: Grounding/Bonding side by side services #45600
12/04/04 09:54 PM
12/04/04 09:54 PM
S
sandsnow  Offline
Member
Joined: Sep 2004
Posts: 167
Irvine, CA, USA
iwire
If we are talking about a duplex (two family dwelling), then there has to be a common area for the disconnecting means to be located in. It can't be in someones side yard where it can be behind a fence. The exception only applies when there is building mangement in place. I only have the '99 at home.

Being in different parts of the country, we may each have a different underatanding or picture in our minds of what this will look like. The way I picture this is like having my service equipment located on my neighbors house, maybe I have the wrong picture here.


This being described as a "two family complex" and being seperate buildings sent up the red flag for me.

Once 230-72(c) is satisfied, then I agree the 2nd building disconnect will be required, plus the grounding req's for 2nd buildings.


Larry LeVoir
Inspector
City of Irvine, CA
Re: Grounding/Bonding side by side services #45601
12/04/04 10:23 PM
12/04/04 10:23 PM
B
BigB  Offline OP
Member
Joined: Mar 2004
Posts: 721
Tucson, AZ USA
This is an existing 2 family complex, the main house built almost 100 years ago with a rental house added in the sixties. The utility is overhead in the alley. Currently the main house is fed overhead with quite a long overhead drop to a recent 100A service with a GES in place. The rental house is fed underground from the main house with 60Amps.
The new buyer wants to relocate the service to the rental house to eliminate the unsightly overhead drop stretching across the property. This will put the service very close to the utility for a mid span hookup.
The new buyer also wants to go to seperate meters. The service equipment on the main house could be used with a meter blank off and fed underground from the rental. This would provide the disco, the GES and the tenant access.
The reason it would not be feasable to run a service lateral to the main house underground is because the property lies between poles and has a mid span tap. To go underground from the utility would require trenching the easement to the next pole. The owner wants to utilize a trench already being dug between the two units for sewage.
The utility will connect the drop to one rigid riser, then run a tap to a second riser which can be emt since it won't have to support the drop. They want the risers within 24 inches of each other.
If I use one riser into a gutter, the gutter will have to have provisions for a utility seal.

[This message has been edited by BigB (edited 12-04-2004).]

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