I have an existing building with a double ended switchboard with each end fed from a different transformer. The owner would like to have a portable generator back up one end of the MSB. In order to do this the transfer switch's normal feed will be from the secondary of the transformer feeding that end. My design calls for a new 4000A transfer switch w/ a 4000A circuit breaker on the normal side of the transfer switch in order to protect the transfer switch and thus the neutral/ground bond existing in the MSB will need to be disconnected and bonded at the transfer switch since this is now the first OCPD/disconnect for the service into this building. The new GEC at the transfer switch will be extended into the building to the grounding bar in the MSB. The owner's engineer reviewing the plans does not want to move the bond and feels the 4000A circuit breaker is not required at the transfer switch. Any thoughts????
