Generator disconnect and emergency shutdown
Generators other than plug-in portables need a lockable disconnect that opens all ungrounded conductors (445.18). Under 445.19 they also need an emergency shutdown; at one- and two-family homes it must be outside the house and readily accessible.
What the code requires
Section 445.18(A) requires generators, other than cord-and-plug-connected portables, to have one or more disconnecting means. Each must open all ungrounded conductors at the same time and be lockable in the open position per 110.25. The disconnect may be inside the generator behind a hinged cover or door, but then a field-applied label (110.21(B)) must show where it is.
For paralleled generators, 445.18(B) requires a disconnect able to isolate the generator from the paralleling system bus. It does not have to be at the generator.
Emergency shutdown is now in 445.19. Under 445.19(A), the generator needs a shutdown means that disables all prime-mover start circuits and requires a mechanical reset. If it is lockable, it may also serve as the 445.18(A) disconnect.
Under 445.19(B), generators over 15 kW at other than one- and two-family dwellings need a remote emergency stop switch outside the equipment room or generator enclosure, at a readily accessible location. Under 445.19(C), generators at one- and two-family dwellings, other than plug-in portables, need an emergency shutdown device outside the dwelling at a readily accessible location. Both must disable the start circuits and need a mechanical reset as in 445.19(A). Either may be mounted on the outside of the generator enclosure, and either must be labeled Generator Emergency Shutdown per 110.21(B).
On the job
- A missing Generator Emergency Shutdown label is a common correction.
- If the disconnect is inside the generator enclosure, a missing label showing its location is a correction.
- Older documents cite 445.18 for emergency shutdown. Under the 2023 NEC, that rule is 445.19.
Exceptions that matter
- Cord-and-plug-connected portable generators are excluded from the 445.18(A) disconnect rule and the 445.19(C) dwelling shutdown rule.
What changed in 2023
The 2023 edition split the old 445.18 so emergency shutdown moved to new 445.19 and allowed the disconnect inside the generator with a location label. The remote stop now applies to other than one- and two-family dwellings and must be readily accessible. Shutdown devices may mount on the generator enclosure and must be labeled, and paralleling equipment became paralleling system bus.
Related sections
- NEC 445.19
- NEC 110.25
- NEC 110.21(B): Requirements for field-applied warning labels
- NEC 230.85: Outdoor emergency disconnect for homes
- NEC 702
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