Services & DistributionQuestion 98 of 521
When a panelboard is used as service equipment, the main bonding jumper must be:
a.Installed to connect the grounded conductor to the panelboard enclosure
b.Omitted because the neutral is isolated
c.Installed only in a downstream sub-panel
d.Replaced by the equipment grounding conductor
Explanation
At service equipment, 250.24(B) and 250.28 require a main bonding jumper connecting the grounded (neutral) conductor to the enclosure. In a downstream sub-panel the neutral is instead isolated, so the main bonding jumper belongs only at the service, never omitted or moved downstream.
Law Reference: 2023 NEC §250.24Practice all 521 questions free — no signup required.
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