service entrance ats?


Senior Member
If the building's main electrical panel (has main breaker) is fed out of an ATS. The ATS's normal power source is fed out of utility xfmr and emergency power source is fed from an outdoor emergency generator, i.e. the whole building is backup by a generator. Questions:

Will a fused disconnect switch or breaker is required between ATS and utility xfmr?

Will the building main's panel be still considered main service disconnect and we have to establish the grounding / bonding there? Or will the ATS be considered main service switch and we need to establish the grounding / bonding at the ATS? If so, Is there such equipment called service entrance ATS???


Senior Member
The ATS will be the service equipment and will require overcurrent protection in it or right next to it. The main bonding jumper will be located in the ATS. SUSE rated ATS's are available.