230.40

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Little Bill

Little Bill

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In article 230.40 ex. #3, it says this:
A one-family dwelling unit and its accessory structures
shall be permitted to have one set of service-entrance conductors
run to each from a single service drop, set of overhead service conductors,
set of underground service conductors, or service lateral.
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Meaning on a single family dwelling you could have a 400A (320A) meter base with dual lugs and feed a 200A panel at the house and feed another building/structure with 200A. Each location would be service entrance conductors and neither would be a feeder. That's allowing one service drop to supply two sets of SE conductors.

The problem I'm having is the inspector is saying he's ok with the two sets of SE conductors but not ok with not grouping the disconnects. On the house the meter is back to back with the inside panel, no disconnect. At the other structure there is a main breaker panel/disconnect mounted on the outside of the structure. I'm pretty sure we have had this discussion before and I looked for the allowance. What I found, and think is the section that allows this is 230.71, which says:
230.71 Maximum Number of Disconnects.
(A) General. The service disconnecting means for each service
permitted by 230.2, or for each set of service-entrance
conductors permitted by 230.40, Exception No. 1, 3, 4, or 5,
shall consist of not more than six switches or sets of circuit
breakers, or a combination of not more than six switches and
sets of circuit breakers, mounted in a single enclosure, in a
group of separate enclosures, or in or on a switchboard or in
switchgear. There shall be not more than six sets of disconnects
per service grouped in any one location.
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The part in bold is what I think would allow the disconnecting means not to be grouped.
What are your thoughts on this?
 
Yeah, how do you group service disconnects for seperate structures and have them still remain services by the code you reference. If you wound up grouping both disconnects at one of the structures you would then have feeders not services.
 
oldsparky52 said:
Are you overhead or underground or a combination?
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Shouldn't matter. One service drop or lateral can supply both buildings. You are not likely to have both a drop and a lateral supplying same voltage and number of phases, most POCO will want it one way or the other. If you go overhead or underground beyond the service point shouldn't matter.
 
You are correct.
There is no difference, other than a common meter socket, than your running one set of UG service conductors from the transformer to the house and one from the transformer to the outside structure.
 
augie47 said:
You are correct.
There is no difference, other than a common meter socket, than your running one set of UG service conductors from the transformer to the house and one from the transformer to the outside structure.
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Actually it's POCO feed from transformer to house, landed on a dual lug meterbase, one set of SE conductors to inside house panel, (back to back) and one set to separate outside structure.
 
Little Bill said:
Actually it's POCO feed from transformer to house, landed on a dual lug meterbase, one set of SE conductors to inside house panel, (back to back) and one set to separate outside structure.
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Meter base means little here, it is just a place to make the connections in. Could be no meter at all and some other junction/splice box to split both ways and still NEC compliant.
 
The grouping applies to individual buildings. if I'm not mistaken.

If the separate building had a disconnect at the meter, the two disconnects there would need to be grouped.
 
LarryFine said:
The grouping applies to individual buildings. if I'm not mistaken.

If the separate building had a disconnect at the meter, the two disconnects there would need to be grouped.
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If the separate building had a disconnect at the meter you are no longer supplying the separate building with service conductors. In that case you can't have any additional service disconnect in/on the house unless it is grouped with all other(s).
 
This is absolutely a NEC compliant installation. However, I know of many POCOs that won't allow it as they want to be able to disconnect all load right at the meter base. There are even some that require a single main. Square D even makes a meter/main with a single 400 amp main with 2 200 subfeed breakers just for these areas.
 
oldsparky52 said:
If overhead I thought just hit the 1st building then the 2nd never bringing the 2nd building conductors down the wall, but then I figured you needed to meter the 2nd building from the 1st building.

How would PoCo install the conductors to the 2nd building? They would hit the 1st building and then the 2nd? I didn't think they would do that. So I guess you would install the underground to the 2nd building from the 1st building as service conductors?
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Run back up (possibly in separate raceway - really more up to POCO than anything on that) and if you have never hit a service disconnecting means they are still service conductors aren't they? Once you pass through service disconnecting means they are feeders regardless if overhead or underground.

Topic of this thread is about the allowance for one service drop or lateral to supply a one family dwelling and an accessory building - as service conductors to each. Otherwise the general rule is that each drop or lateral shall only supply one set of service entrance conductors.
 
Agree it's fine. They key is the wording in 230.71 "for each set". The disconnects for each set must be grouped, not the disconnects for the entire service. You could also ask him what the point of 230.40 ex #3 would be then in his mind, since if all the disconnects had to be grouped, #3 would be pointless as the install would already be covered by 230.40 ex #2.
 
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