Generators

Article 445 covers generators of all kinds, from portable jobsite units to permanent standby sets. It sets the ampacity of the conductors from the generator terminals, the overcurrent protection of the output, required disconnecting means, and the nameplate and marking so anyone knows the unit's ratings.

A central safety idea is that a generator is a source — it can back-feed and energize conductors — so it must be able to be shut down and isolated, and where it connects to premises wiring it coordinates with the transfer-equipment and grounding rules of Articles 700 and 250. Field concerns include protecting a running generator's flexible connections and safe placement of portable units.

When it applies

Article 445 covers how generators get installed, from portable units to permanent standby sets. It sets the ampacity of the output conductors, the overcurrent protection, the disconnecting means, and the marking. The through-line is that a generator is a source of power, so it needs the same disciplined protection and isolation as any other source.

Common mistakes

• Sizing the output conductors below the generator's rated output.
• Leaving out a readily accessible disconnect for the machine.
• Neglecting the transfer equipment so the generator and utility could ever be connected at once.

In the field

On a standby install I confirm the disconnect and the transfer scheme first. A generator that can back-feed the utility line is a lethal hazard to a lineman, so isolation is the piece I never leave to chance.