A ? is a conductor installed on the supply side of a service or separately derived system to ensure the required electrical conductivity between metal parts required to be electrically connected.

Supply-side bonding jumper.

Explanation:

A supply-side bonding jumper is a conductor installed on the supply side of a service or separately derived system to ensure the required electrical conductivity between metal parts required to be electrically connected.

The supply side bonding jumper was referred to as the equipment bonding jumper prior to 2011 NEC when its name changed.

The wire runs from the source of the separately derived system to the first disconnecting means.