Code Q&A

Nov 27, 2007 3:58 PM, By Mike Holt

Q. A single main breaker is installed, then taps supply individual meters with disconnecting means for individual tenants. Should a main bonding jumper be installed at the single main breaker or at each separate disconnect?

A. An un-spliced main bonding jumper complying with 250.28 must be installed between the grounded neutral terminal and the metal parts of the service disconnecting means enclosure in accordance with 250.24(C) [250.24(B)]. Remember that the service equipment is the one to six disconnects connected to the load end of service conductors intended to control and cut off the supply to the building or structure [Art. 100, Service Equipment]. The service you described ends at the load side of the single main breaker. The answer to your question is to install the main bonding jumper at the main breaker, and nowhere else.