transfer switch rating

[ceb58]

I have a installation coming up that has me wondering. 200amp service coming into building to a 200amp fusible disconnect, then they want me to go to the utility side of a auto transfer switch which is rated for 150 amp. The gen. side will be fed from a 30 kw gen. with a 125 amp fusible disco.
I am trying to tell them that the amp rating on the auto transfer switch will dictate the size of the service and the 200amp fuses will need to be dropped to 150 to match the rating of the ATS. Or have I missed something?

Service is 120/208 3 ph Voltage rating on ATS is 240v so that would not come into play

 

[augie47]

Unless the ATS has utility side overcurrent, I agree. The utility fuses would need tpo be 150 amp

 

[LarryFine]

I am trying to tell them that the amp rating on the auto transfer switch will dictate the size of the service and the 200amp fuses will need to be dropped to 150 to match the rating of the ATS.

I agree with you also, Achmed.