Article 100 Prime Mover.
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The prime mover is the machine that supplies the mechanical horsepower to a generator.
Code Change Summary: New code definition of a “prime mover”.
The NEC® has used the term “prime mover” for many code cycles without defining what it is.
- Article 445 (generators) requires a disconnecting means for a prime mover in Section 445.18.
- Article 700 (emergency systems) and Article 701 (legally required standby systems) has rules for prime mover-driven generator sets in Section 700.12(B) and 701.12(B).
- Article 708 (critical operations power systems) has rules for prime mover-driven generator sets in Section 708.20(F).
A prime mover is the machine that supplies the mechanical horsepower to a generator (typically the engine).
Below is a preview of the NEC®. See the actual NEC® text at NFPA.ORG for the complete code section. Once there, click on their link to free access to the 2020 NEC® edition of NFPA 70.
2017 Code Language:
This code definition did not exist.
2020 Code Language:
Article 100.
N Prime Mover. The machine that supplies the mechanical horsepower to a generator.