2 buildings fed from 1 service/meter

[david]

Each building has a service-- what is there to get past. If the power company came from their transformer to each building it would not be different other than having to meter it. The meter does not make it a service. If it were not a service it would need 4 wires going to it.

Do you think those conductors going to the second building are not service conductors?

I would define them as service entrance conductors ,
230.40 subject is service entrance conductors
since we can define the service drop as presented by the op drawing and the service drop is supplying the service entrance conductors at the first building 230.40 states that that service drop can only supply one set of service entrance conductors.

if the second set of conductors running from building 1 meter to the second structure was not defined as service entrance conductors there would be no need for exception no 3.

when applying exception no 3 to (which is limited to a single family dwelling and an accessory building) you have an allowance in the code to still run three conductors (service entrance conductors) between the meter at the first building to the second building

when applying this exception the conductors entering both buildings have always been defined as service entrance conductors not a service lateral or service drop conductors

I cannot see how you would define them as service entrance conductors when the structures are a single family dwelling and an accessory building and define them as something else when the structures involve two dwellings.
To me they are clearly service entrance conductors and 230.40 is applicable

 

[kwired]

I would define them as service entrance conductors ,
230.40 subject is service entrance conductors
since we can define the service drop as presented by the op drawing and the service drop is supplying the service entrance conductors at the first building 230.40 states that that service drop can only supply one set of service entrance conductors.

if the second set of conductors running from building 1 meter to the second structure was not defined as service entrance conductors there would be no need for exception no 3.

when applying exception no 3 to (which is limited to a single family dwelling and an accessory building) you have an allowance in the code to still run three conductors (service entrance conductors) between the meter at the first building to the second building

when applying this exception the conductors entering both buildings have always been defined as service entrance conductors not a service lateral or service drop conductors

I cannot see how you would define them as service entrance conductors when the structure are a single family dwelling and an accessory building and define them as something else when the structures involve two dwellings.
To me they are clearly service entrance conductors and 230.40 is applicable

I agree. But put a second meter out there and supply both buildings from each meter and we suddenly have a different situatioun - especially if the meters are utility owned/controlled. It also comes down to where the "service point" is at.

I can go on about how it has been done for years on farms around here, but that doesn't necessarily mean they are code compliant I guess. Agricultural installations are currently exempt from State electrical inspection here, but the dwelling on the farm is not, so the inspectors are inspecting new homes but nothing else on these places. But it is common for POCO to place a disconnect on a pole with the meter (or a combination unit containing the meter and a disconnect), it may or may not contain overcurrent protection, and we usually run each building to this pole and run as service conductors.

 

[Dennis Alwon]

I don't disagree that they are service entrance conductors however IMO the meaning of grouping has been widely understood to be at each building not grouped on the same building. What purpose does it serve to have a disconnect on the main structure. If that were the case then that would be a feeder to the other building and would require an equipment grounding conductor.

If I enter a meter on one building I can pipe all the around the structure and install my disconnect on the opposite side of where the meter is placed. I see the second set of conductors as a tap of the service lateral even though the NEC may call them service conductors in their diagram but again I am not so sure.

If I feed a building with a 400 amp service set meter and then feed two 200 amp panels do I have 2 sets of service conductors? Are you saying that is not compliant?

230.40 states that that service drop can only supply one set of service entrance conductors.

 

[david]

I don't disagree that they are service entrance conductors however IMO the meaning of grouping has been widely understood to be at each building not grouped on the same building

I would think grouping would mean at the same location (together)

I agree it would be a feeder to the other building grouping of the disconnects would be in compliant with exception 2 (230.40)

I am not saying this would not be compliant
I am saying 230.40 applies

Again 230.40 exception no. 2 would allow for this I am unsure if separate loads in that exception are clearly enough defined.

I would think in the op question the two separate dwellings would be two separate loads and that may be the exception his inspector is using in asking that the disconnects be grouped at the first dwelling
I would think both disconnects would have to be grouped outside if these are two separate owners.

 

[Dennis Alwon]

David I am very confused with all this. I not sure why except. 2 is relevant but except 3 in art 230.40 seems to clearly allow one sets of service conductors to run to each building. Now if they are service conductors being allow between the house and the accessory building then there cannot be a disconnect at the house because then it would not be service conductors.

Of course, you could have a disconnect at the house I just don't see why it is necessary

 

[david]

David I am very confused with all this. I not sure why except. 2 is relevant but except 3 in art 230.40 seems to clearly allow one sets of service conductors to run to each building. Now if they are service conductors being allow between the house and the accessory building then there cannot be a disconnect at the house because then it would not be service conductors.

Of course, you could have a disconnect at the house I just don't see why it is necessary

Sorry that I am confusing you.

It is my contention that the service drop in the op question can only supply one set of service entrance conductors.

There are 5 exceptions to this.

The closes exception that meets what the op has drawn would be 230.40 exception 3, it is however excluded because this is not a single family dwelling and an accessory building to that dwelling

since the service drop supplies the service entrance at the first structure (house # 1) and also feeds the service entrance ( not a feeder ) to house # 2 it does not meet any of the exceptions given under 230.40 1 through 5

exception # 2 would allow a service drop at the first structure to supply more than one service entrance to separate loads as long as the service disconnects are grouped together at one location.

We most commonly see this at trailer park pedestals? one service drop with six service disconnects feeding separate structures (six trailers) with the disconnects grouped at one location.

As you pointed out if you apply exception two for the allowance to supply both service entrance in the OP post the second service entrance must have it's service disconnect grouped with the first service entrance disconnect. That would be at the first (structure)house in the OP question.

As you correctly pointed out the feed than between the service disconnect and the second house would then be a feeder. And require four conductors from the service disconnect to the second house.

230.40. is applicable to the OP question.
A service drop is only allowed to supply one set of service entrance conductors.
To supply any additional service entrance conductors you must be able to meet one of the conditions in exceptions 1 through 5

 

[augie47]

Lets look at a couple of scenarios:
Take two structures..
If we had an overhead drop or underground lateral from a pole to each structure we would have no problem.
If we ran service conductors to a common point, such an underground box and split to each structure, we would have no problem
If we ran to common point such as a pedestal mounted metering point between the two structures most would find that acceptable.
This is not much different than the last scenario. We have service conductors coming to a point outside of structure and splitting to feed two structures.
To me is fits exception #2 as long as the service disconnects at each termination point are grouped.

 

[david]

Lets look at a couple of scenarios:
Take two structures..
If we had an overhead drop or underground lateral from a pole to each structure we would have no problem.
If we ran service conductors to a common point, such an underground box and split to each structure, we would have no problem
If we ran to common point such as a pedestal mounted metering point between the two structures most would find that acceptable.
This is not much different than the last scenario. We have service conductors coming to a point outside of structure and splitting to feed two structures.
To me is fits exception #2 as long as the service disconnects at each termination point are grouped.

Exception two states the service disconnects supplied by the common service drop or lateral have to be grouped at one location.
I do not see how that can be at their individual termination points and still be grouped at one location for the disconnects supplied by the one service drop or lateral.

 

[Dennis Alwon]

I did not catch that the other building was also a home. My bad however I would still consider it the same as it is on the same meter. It is a secondary building /accessory building ???? --- the NEC does not define accessory building. I don't see why the occupancy makes a difference

 

[GoldDigger]

230.40. is applicable to the OP question.
A service drop is only allowed to supply one set of service entrance conductors.
To supply any additional service entrance conductors you must be able to meet one of the conditions in exceptions 1 through 5

Let's look at the actual text of 230.40 in the 2011 Code:

230.40 Number of Service-Entrance Conductor Sets.
Each service drop, set of overhead service conductors, set of underground service conductors,
or service lateral shall supply only one set of service-entrance conductors.

If you meet that, you do not need to rely on one of the exceptions.
So it seems to me that the only question that has to be answered is where the service conductors (drop, lateral, overhead, or underground) end. If they end at the meter enclosure, then both sets of wires from there are service-entrance conductors rather than service conductors and the OP is in trouble.
If the service conductors themselves are considered to run past the meter housing to dwelling #2, then two groups of disconnects would seem to be OK. (The wiring to dwelling #2 would be a separate set of service conductors, although fed from the same drop. ) Somehow I do not think that is going to fly.

Now if there were two meters at dwelling #1, it would argue strongly that there are two separate sets of service conductors, one of which terminates at #1 and one which terminates either at #2 or at the load side of meter #2. Either way 230.40 is satisfied without any exception. YOMV.

(How did this situation come about, anyway?)

 

[ggunn]

Is any of this in any way related to personal injury protection or fire safety, or does it all hinge on what is being called what? I am all for rules and procedures that protect life and property, but when it all boils down to semantic fine points it gets a little ridiculous.

IMO, of course.

 

[Dennis Alwon]

Is any of this in any way related to personal injury protection or fire safety, or does it all hinge on what is being called what? I am all for rules and procedures that protect life and property, but when it all boils down to semantic fine points it gets a little ridiculous.

IMO, of course.

That was my point that what difference would installing a disconnect at the house be then any other service underground that is not protected. I guess it is always safer to install a disconnect without unfused wire running long distance however the NEC allows it without question on the same structure.

 

[GoldDigger]

That was my point that what difference would installing a disconnect at the house be then any other service underground that is not protected. I guess it is always safer to install a disconnect without unfused wire running long distance however the NEC allows it without question on the same structure.

To which I would also add that I would like to know what safety hazard results from connecting two sets of service-entrance conductors to one service in the first place?

 

[ggunn]

So, if the OP were to spray paint "ACCESSORY STRUCTURE" in big letters on the side of the second building, everything would be hunky, right?

 

[RB1]

David,

The NEC does not differntiate between principal uses and an accessory uses, that is a zoning issue. I think for the purpose of the NEC the accessory structure is the structure located remote from the drop. Don't let your code enforcement experience cloud your judgement. The NEC does not deal with zoning isuues.

 

[GoldDigger]

So, if the OP were to spray paint "ACCESSORY STRUCTURE" in big letters on the side of the second building, everything would be hunky, right?

Or even "GUEST HOUSE". Not a full time residence.
And it could be on the side of either the first or the second building.

 

[kwired]

Is any of this in any way related to personal injury protection or fire safety, or does it all hinge on what is being called what? I am all for rules and procedures that protect life and property, but when it all boils down to semantic fine points it gets a little ridiculous.

IMO, of course.

That was my point that what difference would installing a disconnect at the house be then any other service underground that is not protected. I guess it is always safer to install a disconnect without unfused wire running long distance however the NEC allows it without question on the same structure.

I am also in the "what difference would it make club". But you all know how well that sometimes goes when it is still a conflict with what the code says. I think the strictest interpretation does not allow the OP install to pass. But at same time it has been mentioned how little change is needed to make it compliant, like throwing in a second meter and leaving everything else pretty much same as it already is.

 

[david]

Is any of this in any way related to personal injury protection or fire safety, or does it all hinge on what is being called what? I am all for rules and procedures that protect life and property, but when it all boils down to semantic fine points it gets a little ridiculous.

IMO, of course.

That?s been a shifting bench mark for me over my career trying to judge weather any particular rule that I may not have agreed with as any measure of importance as you have stated. The problem is I can only judge that on the limits of my own expertise and my own personal experiences.

That?s my we rely on a room full of experienced individuals to act on our behalf and develope this standard as a min. standard do just as you stated.

 

[david]

To which I would also add that I would like to know what safety hazard results from connecting two sets of service-entrance conductors to one service in the first place?

With out hard data one could only protect hypothetical?s

The more service entrances connected to a single drop the more paths for a fault to travel. The more equipment to be damage .
If these service entrances are connected to more than one building the more buildings effected by one particular service supply (drop or lateral) if they fail.

Maybe the intent was to limit each building to one supply since you see this theme in regards to manufacture housing, feeders to secondary buildings through- out the NEC.

How many times have you look at wiring in a basement and said what a rats nest. I would guess limiting the no. of service entrance tied to one supply would limit the amount of rats nest that would develope if there where no limit sestablished.

 

[david]

David,

The NEC does not differntiate between principal uses and an accessory uses, that is a zoning issue. I think for the purpose of the NEC the accessory structure is the structure located remote from the drop. Don't let your code enforcement experience cloud your judgement. The NEC does not deal with zoning isuues.

The NEC was never met to be a building code.

However the building codes do define dwellings ,single family dwellings, and accessory structures. I would think the individuals had believed these structures where defined when they wrote this section of the code.