Overcurrent Protection

Certain overcurrent protection requirements apply to circuits rated 600 volts nominal or less, and to feeders and branch circuits energized at more than 600 volts nominal.

The following requirements apply to circuits rated at 600 volts nominal or less:

• Conductors and equipment must be protected from overcurrent in accordance with their ability to safely conduct current.
• Unless all conductors of the circuit are opened simultaneously, overcurrent devices cannot interrupt the continuity of the grounded conductor.

The following requirements apply to feeders and branch circuits rated at more than 600 volts nominal:

• Feeder and branch-circuit conductors must have overcurrent protection in each ungrounded conductor.
• Each protective device must be capable of detecting and interrupting all values of current that can occur at its location in excess of its trip setting or melting point.

The full listing of the overcurrent protection requirements can be found in 29 CFR 1910.304.

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