Service disconnect for a detached dwelling building

[Alexis]

Hey Everyone!

We installed a new service for 8 units spreaded between 2 separate buildings. Local utility now requires only one drop per lot.
We ran 4 new conduits in between the buildings to subfeed the 4 units in the second building. Each of the sub panels has a main breaker wirh hold down kit to serve as a service disconnect.
Local inspector gave us correction to install another service disconnect to the feeders as close to the wire entering the building as possible.

The inspector has not provided me with a code refference, but I believe they reffer to 230.70 (A) which refers to services and not feeders. We have a main service panel with 60A breakers installed, so it is not a service anymore, but a feeder.

Am I missing something? We always did detached structures like ADUs and garages with sub panels with a main breaker and never with a service disconnect on the outside.

Thank you!!

 

[suemarkp]

The equivalent feeder rules to a detached structure are in 225.30 and for the disconnect(s) 225.31, 225.33, 225.34 ... and just keep going for al the rules about disconnects to a detached structure.

The primary limitation is one feeder to a detached structure, not 4. You are now allowed to have multiple feeder like you've done as long as all 4 originate from the same panelboard and terminate in a disconnect or main breaker panelboard (225.30(B)). But you need to watch the other rules about grouping the building disconnect and where it need to be on that building.

 

[Alexis]

The equivalent feeder rules to a detached structure are in 225.30 and for the disconnect(s) 225.31, 225.33, 225.34 ... and just keep going for al the rules about disconnects to a detached structure.

The primary limitation is one feeder to a detached structure, not 4. You are now allowed to have multiple feeder like you've done as long as all 4 originate from the same panelboard and terminate in a disconnect or main breaker panelboard (225.30(B)). But you need to watch the other rules about grouping the building disconnect and where it need to be on that building.

Thank you so much! So looks like even if we could terminate into the main breaker of the sub panels of each unit, the 225.30 (B) would call to have disconnects grouped in one location anyway, so make sense to install it by the entrance of the conductors.

What would happen if we would have 7 or more units? This would make it illegal to install at all, right? We had a utility company which tried to make us do the same thing for 9 units (merge 2x400A services on separate buildings into one 800A on one) but we were able to get an exception for that job..

 

[suemarkp]

I think the desire by the code making panel has been to run one feeder to a building. Multiple feeders or services are grandfathered but not desired. So if you had 7 units, you'd run say a single 400A feeder to the building and have a single 400A disconnect on the outside or nearest the point of entry to the building. You can then distribute from there to 7 or more units. You could also run say two or three 200A feeders and split out from those at 60A to 100A each as needed to multiple units.

This newer rule allowing multiple feeders to a detached structure (as long as they are fed from a common enclosure) helps reduce costs when you are splitting things out so you have the option now of multiple smaller feeders or one large one. But the magic number for max disconnects has always been 6. Not sure why, but it is.

If a utility wanted metering on building A for units in building B, that would be a problem as once you hit a meter stack the outputs need to be kept separate. So as long as they only want a single feeder or service to a structure (or even up to 6), there is no problem as long as the metering is done on the building where things split out after the main disconnect.