One building fed from another, with a twist

[scotteng]

We design grocery store anchored neighborhood retail shopping centers. These all have an inline retail building attached to one side of the grocery store. The grocery store has a dedicated electrical service fed by a dedicated transformer. The retail building has a separate transformer that feeds a typical retail service setup, generally a trough with multiple meter/main disconnects for each tenant suite. The grocery anchor is now locating their separate liquor stores in the first tenant bay of the adjacent inline retail. The grocery store wants to feed this first suite directly from their service because their store is on generator backup and this ensures the liquor store would also have generator backup. To date, what we have been feeding that tenant suite through a double-throw switch on the outside of the suite. The retail and the grocery store provide the two inputs of the double throw switch with the liquor panel being the output. We believe 225.30(A)(4) and/or (6) permits this scenario given that the grocery store is backed up by an optional standby generator and this provides "additional reliability". The grocery tenant is now asking if we can omit the retail service feed altogether because they will never use it as they intend for the liquor store to be powered from the grocery store service at all times (as opposed to someone throwing the switch if the retail service goes down). I believe providing a dedicated second feeder from a separate building without the retail feeder no longer meets one of the exceptions under 225.30(A). What are the opinions on having a multi-tenant building where four of the five tenant suites are fed from a the retail service but one tenant suite is fed from another building? Is this permitted? I am aware of the grounding concerns with this scenario, but this is strictly a question regarding what the second feeder is permissible.

 

[tortuga]

I believe providing a dedicated second feeder from a separate building without the retail feeder no longer meets one of the exceptions under 225.30(A).

It does not need to, the liquor store would be supplied by only one supply, 225.30 is satisfied.

What are the opinions on having a multi-tenant building where four of the five tenant suites are fed from a the retail service but one tenant suite is fed from another building? Is this permitted?

Yes

 

[hmspe]

I assume that the site has two services because the major tenant space and the shops are considered separate buildings under the building code. If so crossing over from the major tenant's service to one of the shops would an outside feeder to the shops building. You would need to comply with 225.30. We don't know about house panels and loads. The one allowed outside feeder to the shops might have already been used for exterior lighting or other loads.

You may need to discuss this with the AHJ.