Part VII of Article 230 provides the requirements for overcurrent protection of service equipment. Here are some highlights from this part of the NEC that are worth reviewing.
You must provide an overcurrent protection device (OCPD) in series with each ungrounded service conductor. Its rating or setting can’t exceed the ampacity of the protected conductor [230.90]. Of the five exceptions, perhaps the most critical is that for fire pumps. The fire pump OCPD must comply with 695.4; continuity of power is paramount.
- You can’t insert an OCPD in a grounded conductor, unless it simultaneously opens all conductors of the circuit [290.90(B)].
- Each service OCPD must be an integral part of the service disconnecting means (e.g., part of a constructed panel) or be located right next to it [230.91].
- Service OCPDs that lock must comply with 230.92.
- You must provide ground fault protection for solidly grounded wye services that are between 150V (to ground) and 1,000V (phase-to-phase). You must provide this at each service disconnect rated 1,000A or more [230.95].
- The ground fault system must cause the service disconnect to open all ungrounded conductors of the faulted circuit [290.95(A)].
- The NEC requires performance testing of the ground fault system when first installed [230.95(C)]. The owner should ensure such testing is regularly scheduled thereafter.
