Wire Size

[Alwayslearningelec]

If you have a 200A disconnect fed from bus tap could you have #1’s XHHW feeding the disconnect? I ask because #1’s are rated for 130A. That is the line side.

The load side of disconnect is feeding a 100A ATS which then feeds a 75kva xfmr,

From the 200A disconnect switch to the ATS and ATS to 75kva xfrmr is also feed with #1’s. Does that make sense? Thanks.

 

[don_resqcapt19]

No

If you have a 200A disconnect fed from bus tap could you have #1’s XHHW feeding the disconnect?

Tap conductors must have an ampacity at least equal to the rating of the load end OCPD. The "round-up" rule in 240.4(B) does not apply to tap conductors. If this is a fusible disconnect, it would be fine with 125 amp fuses and 1 AWG copper.

 

[infinity]

The load side of disconnect is feeding a 100A ATS which then feeds a 75kva xfmr

As Don said this is fine as long as the disconnect has an OCPD not exceeding the ampacity of the condcutors. As you stated the conductors are rated for 130 amp so a 100 amp, 110 amp, or 125 amp OCPD would be code compliant. Since you have a 200 amp disconnect if fuses are being used then I would go with 110 amps due to the fuse gap size of the 200 amp disco.