Code Change Summary: Revisions clarify when an additional disconnecting means is required for outdoor emergency generator sets.

New code language really changes the game for those installing outdoor emergency backup generators. In order to omit installing an additional disconnect where generator conductors serve or pass through a building, the old code language required the generator to be equipped with a readily accessible disconnecting means that was suitable for use as service equipment in accordance with 225.36.

The new code language still allows no additional disconnecting means where generator conductors serve or pass through a building as long as:

• The generator disconnect is readily accessible
• The generator itself has its own lockable disconnecting means in compliance with 445.18
• The disconnecting means is located within sight of the building or structure supplied

If the generator conductors do however terminate at a disconnecting means in or on a building or structure, the disconnecting means must meet the requirements of 225.36 which requires the disconnecting means to be a circuit breaker, molded case switch, general-use switch, snap switch, or other approved means.

Where applied in accordance with 250.32(B), Exception, the disconnecting means shall be suitable for use as service equipment.

The same code change occurred in 701.12(B)(5) for legally required standby systems and 702.12(A) for optional standby systems.

Below is a preview of the NEC^®.  See the actual NEC^® text at NFPA.ORG for the complete code section. Once there, click on the “free access” tab and select the applicable year of NFPA 70 (National Electrical code).