Onan ATS grounding

thought #1 is it service rated?

you probobly need a service disconnect before the ATS from the utility, in which case the neutral and earth ground need to be seperate at the ATS

#2 no, on the two wires under one lug, unless it's rated for more than one

#3 the cabinet will need to be grounded as a serparate item, (ie; as a panel would be)with the neutral and grounding isolated from each other, that is assuming that in your state you DO need the service disconnect ahead of the ATS

#4 if you lived in this state, the gen set and the service disconnect each require their own ground rod, this state strictly adheres to the NEC.

hope that helps

Thanks for your thoughts. The transfer switch is fed from a breaker in the main panel -- it is not the Service Entry. Therefore, it does have an isolated neutral bar (with the three lugs, for the three wires). The main service entrance ground serves (per the Cummins manual and our inspector) as the ground for the genset and transfer switch -- hence the necessity I see for ensuring the ground wires are well connected in the transfer switch. I have simply added an additional ground lug, bonded to the steel cabinet of the transfer switch. And everything seems to work as it should. I'm just interested that there weren't three lugs provided.