445.18 Disconnecting Means Required for Generators.

Example of a generator with provisions for locking the starting mechanism in the off position.
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Example of a generator with provisions for locking the starting mechanism in the off position.

Code Change Summary: Revisions were made to clarify when a disconnecting means is required for a generator.

As a general rule, generators must be equipped with a disconnecting means that can be locked in the open position.

As well, the disconnecting means must be able to disconnect the generator, all protective devices and control apparatus entirely from the circuits supplied by the generator.

New changes in this section make it clear that the disconnection requirements do NOT apply to cord- and plug-connected portable generators. For other than cord- and plug-connected portable generators, in order to omit the required disconnecting means, the following must apply:

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).

2011 Code Language:

445.18 Disconnecting Means Required for Generators.

Generators shall be equipped with disconnect(s), lockable in the open position, by means of which the generator and all protective devices and control apparatus are able to be disconnected entirely from the circuits supplied by the generator except where both of the following conditions apply:

(1) The driving means for the generator can be readily shut down.

(2) The generator is not arranged to operate in parallel with another generator or other source of voltage.

2014 Code Language:

445.18 Disconnecting Means Required for Generators.

Generators shall be equipped with a disconnect(s), lockable in the open position by means of which the generator and all protective devices and control apparatus are able to be disconnected entirely from the circuits supplied by the generator except where the following conditions apply:

(1) Portable generators are cord- and plug-connected, or

(2) Both of the following conditions apply:

a. The driving means for the generator can be readily shut down, is rendered incapable of restarting, and is lockable in the OFF position in accordance with 110.25.

b. The generator is not arranged to operate in parallel with another generator or other source of voltage.

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445.18 Disconnecting Means Required for Generators.

Below is a Real Question from our Electrical Continuing Education Courses for Electrical License Renewal:

Which of the following is a condition required in order to be able to omit the disconnecting means for a generator?

A: The generator cannot be portable.
B: The driving means for the generator can be readily shut down, and is rendered incapable of restarting.
C: The generator must operate in parallel with another source of voltage.
D: The generator start switch must be able to be locked in the closed position.
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