Different services for a town-home type build-out?

Cartoon1

Senior Member
Location
Florida
Occupation
Electrical Engineer
I have a project that is going to be composed of huge luxury type town-homes about 4,500sqft a piece (total for the whole build out is 18,000 sqft). There will be 4 of them in the same structure that is separated by a 2-hour fire wall (so 4 town homes in same building). Based on initial load calculation I'm going to need 400Amp 240/120 single phase to each town-home. I usually provide meter-center-stack for condo/town home layouts but in this particular case the service requirement per town home is high, i have not seen any manufacturer that provides a stacked meter center with a seperate 400amp mains/meters to each town home, (maximum i seen is 200A a meter). I was planning on providing a separate 400Amp service to each town home for a total of 4 separate mains for the building. Similar to NEC figure exhibit 230.2.

My question is and this where the confusion for me comes, does the 4 separate 400A mains need to be next to each other or would it be okay to put them around the building closest to each town home? Also, does the 4 disconnects need to be all fed from the same utility transformer or is it okay to feed them from different utility transformers? I'm considering these town homes as separate structures and it is allowable to have separate service coming in to each one of them because of the firewall between them, is that a reasonable assumption for something like this?

Thank you
 

Rick 0920

Senior Member
Location
Jacksonville, FL
Occupation
Electrical Instructor
Art. 230.2 states that a building shall be supplied by only 1 service. Art. 230.71 states that you can use up to six disconnecting means in lieu of a main if they are grouped. If you want to use (4) 400A mains, they need to be grouped. If you want to have a 1600 amp fusible disconnect as your main, then the 400 amp disconnects can be placed on each unit apart from one another.
 

Canton

Senior Member
Location
Virginia
Occupation
Electrician
Depends, the devil is always in the details. If you have one large structure divided by “Fire Walls”, then you may have multiple buildings/occupancies, which it sounds like you do.

If this is like the town home rows we have here, then you can a have a service/service lateral running to each, and set a 400 amp at each.
 

kwired

Electron manager
Location
NE Nebraska
Art. 230.2 states that a building shall be supplied by only 1 service. Art. 230.71 states that you can use up to six disconnecting means in lieu of a main if they are grouped. If you want to use (4) 400A mains, they need to be grouped. If you want to have a 1600 amp fusible disconnect as your main, then the 400 amp disconnects can be placed on each unit apart from one another.
230.2 also continues on to say unless permitted in 230.2 A through D. (B)(1) would typically be permissible in situations like OP has. Run a 400 amp service to each occupancy. This of course might need to be agreeable with the serving POCO but certainly is ok with NEC.
 

texie

Senior Member
Location
Fort Collins, Colorado
Occupation
Electrician, Contractor, Inspector
A townhouse in the legal and code sense is a separate structure from its neighbor. The unit owner owns the land and structure all the way to the roof. Each gets it own service and other utilities to that unit. Nothing can pass over, under or in a neighboring unit. Just like a single family dwelling.
That said, there are sometimes buildings that are built townhouse style but are really condos and then you would likely have a central meter bank, etc. You need to know what these units are in the legal sense.
 

Cartoon1

Senior Member
Location
Florida
Occupation
Electrical Engineer
230.2 also continues on to say unless permitted in 230.2 A through D. (B)(1) would typically be permissible in situations like OP has. Run a 400 amp service to each occupancy. This of course might need to be agreeable with the serving POCO but certainly is ok with NEC.

100% Agreed. Where i get hung-up is if i decided to put a meter and a 400A enclosed breaker for each town-home separately. Does that 4 (400) services have to be next to each other or can two go on each side of the building since two of the town-homes are in the middle and have no space in front or back of them. Of course i'm assuming all will be fed separately with the same utility transformer. There isn't somewhere in the NEC where it makes that clear, the figure for 230.2 shows them separate by each other on the same wall.
 

cadpoint

Senior Member
Location
Durham, NC
This so smells like a Design Build where no EE is involved and the Architect is but not a landscaper or site plans,
They only brought in a Surveyor because they need one for, but the client will appreciate the low cost where the GC
pockets every spare dollar.
 

cadpoint

Senior Member
Location
Durham, NC
This so smells like a Design Build where no EE is involved and the Architect is but not a landscaper or site plans,
They only brought in a Surveyor because they need one for, but the client will appreciate the low cost where the GC
pockets every spare dollar.
Sorry I see you are the engineer!
 

Cartoon1

Senior Member
Location
Florida
Occupation
Electrical Engineer
This so smells like a Design Build where no EE is involved and the Architect is but not a landscaper or site plans,
They only brought in a Surveyor because they need one for, but the client will appreciate the low cost where the GC
pockets every spare dollar.
Originally the design I provided was a main circuit breaker 1000A that feeds separate 400A breakers with their separate metering to each town-home based on load calcs. The contractor thinks that they can save on cost if they directly feed separate 400A breaker/meter to each town home tenant from the same utility transformer.
 

augie47

Moderator
Staff member
Location
Tennessee
Occupation
State Electrical Inspector (Retired)
Unless you get easements, you are likely to have a service line to each unit not crossing the others property. POCO would decide on the number of transformers and location.
 

JohnE

Senior Member
Location
Milford, MA
Depends, the devil is always in the details. If you have one large structure divided by “Fire Walls”, then you may have multiple buildings/occupancies, which it sounds like you do.

If this is like the town home rows we have here, then you can a have a service/service lateral running to each, and set a 400 amp at each.

A 2 hr rated wall is a fire partition. A fire wall would be a masonry or concrete wall dividing the units and extending through the roof. Fire walls will create separate fire areas, but it is still considered one building. The separate fire areas will be treated almost like a separate building in the sense of fire protection and other building code applications.
 

JohnE

Senior Member
Location
Milford, MA
Unless you get easements, you are likely to have a service line to each unit not crossing the others property. POCO would decide on the number of transformers and location.
Around here, a townhouse like this is generally one property and easements are not required.
 

JohnE

Senior Member
Location
Milford, MA
A townhouse in the legal and code sense is a separate structure from its neighbor. The unit owner owns the land and structure all the way to the roof. Each gets it own service and other utilities to that unit. Nothing can pass over, under or in a neighboring unit. Just like a single family dwelling.
That said, there are sometimes buildings that are built townhouse style but are really condos and then you would likely have a central meter bank, etc. You need to know what these units are in the legal sense.
Townhouse is a building code term, not an ownership term. A townhouse can be owned by one entity or, if it is a condo, which is a form of ownership, each unit may be owned individually. Generally the owner of each unit owns just the interior, but may own the exterior. The condo docs will spell everything out. The condo docs should spell out all easements, such as electrical passing through the interior of one unit to another.
 

Engser18

Member
Location
US
Occupation
Engineering
100% Agreed. Where i get hung-up is if i decided to put a meter and a 400A enclosed breaker for each town-home separately. Does that 4 (400) services have to be next to each other or can two go on each side of the building since two of the town-homes are in the middle and have no space in front or back of them. Of course i'm assuming all will be fed separately with the same utility transformer. There isn't somewhere in the NEC where it makes that clear, the figure for 230.2 shows them separate by each other on the same wall.
you are confusing between number of services and number of SD mean.
1. if you run your 1000A service conductors from utility Xformer then these SD(s) shall be group. this is 1 service. (230.70)
2. if you run 400A service conductors from utility Xformer to each unit, they doesn't need to be group. This is 4 services (230.2)

Either case will be met the NEC. Local AHJ and POCO are different story.
 

kwired

Electron manager
Location
NE Nebraska
you are confusing between number of services and number of SD mean.
1. if you run your 1000A service conductors from utility Xformer then these SD(s) shall be group. this is 1 service. (230.70)
2. if you run 400A service conductors from utility Xformer to each unit, they doesn't need to be group. This is 4 services (230.2)

Either case will be met the NEC. Local AHJ and POCO are different story.
But can you put two of the disconnects on one side of the building and two on the opposite side and feed four occupancies?

I don't think NEC is all that clear about this but I do think they intend to either have them grouped all at one location or one service to each occupancy, no mix and matching.
 

Engser18

Member
Location
US
Occupation
Engineering
But can you put two of the disconnects on one side of the building and two on the opposite side and feed four occupancies?

I don't think NEC is all that clear about this but I do think they intend to either have them grouped all at one location or one service to each occupancy, no mix and matching.
there are several ways to do this. You can install 1 service, 2 services, or 4 services. As long as your service conductors are exceeded ampacity of load cal for each service including any conductors derate and each service can’t have more than 6 SD. However, it is hard to justify 2 services due to each unit is diff tenant.
 

kwired

Electron manager
Location
NE Nebraska
there are several ways to do this. You can install 1 service, 2 services, or 4 services. As long as your service conductors are exceeded ampacity of load cal for each service including any conductors derate and each service can’t have more than 6 SD. However, it is hard to justify 2 services due to each unit is diff tenant.
copied from 2017
1674407145148.png
This possibly could use some rewording to clarify exactly what it is they want here.

As written if the disconnects are on the outside then most cases they are accessible to all occupants, and probably should all be in same location to fulfill wording of other requirements. If disconnects are inside then this section allows them to be inside each individual occupancy.
 

Cartoon1

Senior Member
Location
Florida
Occupation
Electrical Engineer
copied from 2017
View attachment 2563702
This possibly could use some rewording to clarify exactly what it is they want here.

As written if the disconnects are on the outside then most cases they are accessible to all occupants, and probably should all be in same location to fulfill wording of other requirements. If disconnects are inside then this section allows them to be inside each individual occupancy.

Yes that is where my confusion is, it is definitely not clear based on their wording.
 

Cartoon1

Senior Member
Location
Florida
Occupation
Electrical Engineer
there are several ways to do this. You can install 1 service, 2 services, or 4 services. As long as your service conductors are exceeded ampacity of load cal for each service including any conductors derate and each service can’t have more than 6 SD. However, it is hard to justify 2 services due to each unit is diff tenant.
I believe having 1 service with 4 meters in the same location is the cleanest way to do this. Without getting into any special type of permission from anyone.
 
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