The electrical code is very specific regarding where the grounded (neutral) conductor may be used for bonding or grounding of equipment. That permission generally ends at the service disconnect. This information is found in article 250 and more specifically 250.24 which requires the connections at the service disconnecting means. The definitions of service and the related items is found in article 100, definitions. Section 250.24 (A)(5) goes further to specifically state a “grounded conductor shall not be connected to normally non–current-carrying metal parts of equipment, to equipment grounding conductor(s), or be reconnected to ground on the load side of the service disconnecting means” to provide further clarification. The fact the transfer switch contains the first disconnecting means and overcurrent, the service ends at that enclosure. Beyond that point, the grounded and grounding conductors are separated.
