110.31 When is a 3 Hour wall necessary

[ed downey]

I have a project that the Main incoming service is 15kV conductors (12,470V) feeding to a Unit Substation. The Main service is located in a Main Electrical Room in a Parking Garage below the Office Building.

Since we have a Unit Sub-Station Transformer do we have to meet the requirement of a Vault as shown in 110.31(A)?

Thanks,
Ed

 

[charlie b]

It doesn't fit the description in 450.21(C). If it also doesn't fit the description in 450.26, then you don't need a "vault."

 

[cowboyjwc]

If the transformer is POCO owned I would say that it doesn't fall under the NEC and so 110.31(A) would not apply.