Inquiring about the cable selection for areas outside the service entrance, specifically for the underground conduit.

[Rory Choicllroy]

A 300KW pad-mounted transformer and a manual transfer switch will be installed outside the building.

From the external transformer to the external manual transfer switch on the primary side, it falls within the service entrance section.

For this segment, USE-2 cable is planned for the underground conduit.

From the secondary side of the manual transfer switch to the main electrical panel inside the building, THW or THHN/THWN cable is intended for use in the underground conduit.

I would like to inquire whether this setup violates the NEC (National Electrical Code) regulations.

 

[electrofelon]

A 300KW pad-mounted transformer and a manual transfer switch will be installed outside the building.

From the external transformer to the external manual transfer switch on the primary side, it falls within the service entrance section.

For this segment, USE-2 cable is planned for the underground conduit.

From the secondary side of the manual transfer switch to the main electrical panel inside the building, THW or THHN/THWN cable is intended for use in the underground conduit.

I would like to inquire whether this setup violates the NEC (National Electrical Code) regulations.

Your cable selection is fine, but you could also use the THHN from the transformer to the xfer switch - it doesn't have to be USE

Is there a service disconnect built Into or immediately adjacent to the transfer switch? There needs to be .

 

[augie47]

Is there a service disconnect built Into or immediately adjacent to the transfer switch? There needs to be .

Is that required on a manual transfer switch ???

 

[Strathead]

Is there a service disconnect built Into or immediately adjacent to the transfer switch? There needs to be .

Is that required on a manual transfer switch ???

My opinion is yes. The transfer switch isn't merely a utility side isolation means for power company. It is on the secondary side of the meter. That makes it the first means of disconnect. We actually just had a very similar installation where the Electrical Engineer specified a non fused disconnect on the line side of the MTS. Square D and us insisted on this being fused even though he shot down the original submittal. I assume either AHCA or the AHJ "corrected" him.

 

[electrofelon]

Is there a service disconnect built Into or immediately adjacent to the transfer switch? There needs to be .

Is that required on a manual transfer switch ???

I don't see anything in 230.82 that would allow the transfer switch to be considered anything other than the service disconnect, and the service OCPD must be integral or immediately adjacent there to ....

Perhaps if this were a dwelling (which I assume it is not based on the 300kva transformer) , perhaps the xfer switch could be considered the emergency disconnect not service equipment?

 

[Rory Choicllroy]

The MTS is located outside the electrical room, and is connected by an underground conduit from the secondary side of the MTS to the electrical room main panel.

Are there any problems with NEC CODE if I use thw conductor. (thw, not thwn)

 

[LarryFine]

The N is a nylon jacket. The W is still for wet.