One service for two buildings

[dcushing]

Hello All,

I have a question regarding serving one building through another.
The project consists of one large building and one (comparatively) smaller building. We're being made to put in a utility transformer vault for both buildings and I'd like to avoid having to put in one of these vaults due to the small footprint of the building. These buildings are fire separated and have two different addresses, fire alarm system etc. They do connect on the upper levels with fire shutters separating the buildings.

The picture attached is essentially what I'd like to do. I'm confused about whether the entire service needs to be "outside" building #1 or if it's considered a feeder until it reaches building #2. I'd also like to vet any obvious issues that I might have overlooked before I go forward with making this proposal since this isn't something that I've done before.


I've stripped the oneline down to what's needed for this question for illustrative purposes.



Thank you I appreciate the help.

 

[Dennis Alwon]

If you are under the concrete then you are not inside the building so this should not be an issue

230.6 Conductors Considered Outside the Building. Conductors
shall be considered outside of a building or other structure
under any of the following conditions:
(1) Where installed under not less than 50 mm (2 in.) of
concrete beneath a building or other structure
(2) Where installed within a building or other structure in a
raceway that is encased in concrete or brick not less than
50 mm (2 in.) thick
(3) Where installed in any vault that meets the construction
requirements of Article 450, Part III
(4) Where installed in conduit and under not less than
450 mm (18 in.) of earth beneath a building or other
structure
(5) Where installed within rigid metal conduit (Type RMC)
or intermediate metal conduit (Type IMC) used to
accommodate the clearance requirements in 230.24 and
routed directly through an eave but not a wall of a building

 

[zbang]

Just curious, are they on different parcels of land? (one parcel can have multiple postal addresses)

If it's the same land, same owner, same tenant, etc, that might fly but going to building #2 would be a feeder, not a service. OTOH if they're ever separated, there will be big problems.

If the PoCo wants to make them separate services (and meters), it's gonna be a hard uphill battle, I think.

 

[tom baker]

In the electric room #1 the 1200A breaker to electric room #2, that is a feeder, not a service and being encased in concrete it is outside of electric room #1.
Nice drawing by the way

 

[Dennis Alwon]

In the electric room #1 the 1200A breaker to electric room #2, that is a feeder, not a service and being encased in concrete it is outside of electric room #1.
Nice drawing by the way

That correct that part is a feeder so it isn't an issue anyway. I missed that

 

[augie47]

As drawn, if switchboard 1 is INSIDE, I can be a potential problem with 240.24(B).
I would think it would be better to feed Switchboard 2 directly off the collector buss with the conduits concrete underground or under slab.

 

[dcushing]

As drawn, if switchboard 1 is INSIDE, I can be a potential problem with 240.24(B).
I would think it would be better to feed Switchboard 2 directly off the collector buss with the conduits concrete underground or under slab.

I thought about that too, the issue I saw was that I'd need a cable tap box and I don't know if we could get it in the vault. There's a few other taps off the collector bus already that I'm not showing so we'd have to work out if it would fit.

So the consensus I'm getting is that as shown this is a feeder and not considered a service. Its more of a question of how they'd split it in the future if needed.
Zbang - These are on different parcels of land the buildings just happen to be side by side.

 

[texie]

Why are there 2 POCO transformers in parallel?

 

[Russs57]

I agree with Augie47. Or at least that is how it is done in my area now. That said, in the past we did do it the way your drawing is shown.