For a 500-ampere service supplied with 750-kcmil copper as the largest ungrounded service-entrance conductor, what is the minimum size aluminum bonding jumper for the water piping system?

To determine the minimum size aluminum bonding jumper required for the water piping system in a service of 500 amperes with a 750-kcmil copper service-entrance conductor, it is essential to reference the National Electrical Code (NEC) guidelines regarding bonding and grounding.

According to NEC Section 250.102(C), the size of the equipment bonding jumper is based on the largest ungrounded conductor size. In this scenario, since the largest ungrounded service-entrance conductor is 750-kcmil copper, the corresponding minimum size for the aluminum bonding jumper must be calculated.

In general, bonding jumper sizes are specified in Table 250.102(C) of the NEC. For a 750-kcmil copper conductor, the code requires that the aluminum bonding jumper be at least 4/0 AWG. This is due to the fact that aluminum conductors have a lower ampacity compared to copper conductors, and thus to properly bond and convey fault current effectively, a larger size is needed.

This requirement ensures that the bonding jumper can adequately participate in fault conditions, thereby providing a reliable path for fault current, minimizing potential hazards such as shock or fire. The choice of 4/0 AWG aluminum as