Transformer Feeder Tap

[elecshop]

I have an existing transformer servicing an industrial building. The service conductors run underground from the transformer to the main switchgear outside.
I want to tap a new feeder from that transformer to service an addition to the building. Can I run the feeder taps along the exterior wall instead of underground trenching? I could not find any restriction in NEC regarding running taps on lengths >25ft, except for mentioning that feeders have to be "protected against physical damage". Is that open to AHJ interpretation, or if I use a RMC conduit / RGC conduit that should be sufficient protection?

 

[don_resqcapt19]

First, are you dealing with service conductors or feeder conductors? You are using both terms.
Is the transformer utility owned or customer owned? Where is the service point?

 

[elecshop]

Transformer is utility owned, and I am adding a new tap to service the new addition. These qualify as service conductors - they terminate in a new meter / CT cabinet.

 

[electrofelon]

Transformer is utility owned, and I am adding a new tap to service the new addition. These qualify as service conductors - they terminate in a new meter / CT cabinet.

This is a bit sticky. You have to think about whether this will be a second service, or a second to set of service conductors. If the former, you will need to meet one of the requirements in 230.2 for a second service. If it's the latter, you will need to meet one of the exceptions in 230.40.

 

[augie47]

agree with Post #4.. before you address routing you need to confirm the "addition" qualifies as a separate building (fire walls , etc.) or you meed the requirements of 230.2.
IF you satisfy the second service rules IMO running the RMC on the outside of the 1st building would be allowed but I would definitely run it by you AHJ as it is, as electrofelon noted, sticky.

 

[elecshop]

This addition services a new fire pump room exterior to the building i.e. an addition. There will be a new meter and CT cabinet and a new service disconnect (optional since fire pump does not necessarily require service entrance disconnect / direct connection allowed per NEC 695).
The AHJ would require additional permitting if trenching is required. That's why a suggestion of exterior conduit was brought up.

You have to think about whether this will be a second service, or a second to set of service conductors.

Don't both scenarios necessitate a new meter i.e. a new electric 'service' from a utility standpoint?

 

[don_resqcapt19]

Since this is a fire pump there voltage drop requirements in 695.7 that can be come an issue with long runs of conductor, and even with the rating of the service transformer.