While portable electric generators can be a source of electricity when disruptions

occur to the normal supply of power, they shall be used with caution. An

improperly used generator can damage equipment belonging to the owner of the

generator or equipment belonging to others and may start a fire or cause death.

If a generator is operated in a garage or outside building, it should be properly

ventilated, since its exhaust contains carbon monoxide, which can cause serious

The easiest method for using a generator is to simply plug the desired appliance,

tool or motor directly into the proper electric outlet on the generator. (The

electrical circuits.) It is important to use only high quality, well insulated,

grounded cord sets rated at the same or higher voltage and current as the

generator outlet being used. If the generator outlet is protected by a circuit

breaker, the cord set should be rated at the same amperes (or higher amperes)

as the circuit breaker.

building electrical circuits. Electrocution of Power Company, rescue, fire or other

emergency personnel can result if the generator circuit is not properly isolated

from the electric utility power circuit. Also, if the generator and utility power are

not isolated from each other and utility power is restored while the generator is

supplying power, utility power can backfeed through the generator. This can

result in damage to the generator and an electrical fire can then occur.

A generator connected to the building’s circuits or wiring shall have the

installation made by a qualified, licensed electrician and meet all requirements of

the authorities having jurisdiction. The generator shall be connected through a

double-pole, double-throw transfer switch. The Customer shall supply a

disconnect method acceptable to the Company. The location shall be on the

outside of the facility accessible to Company personnel at all hours. The

following installation method is recommended:

Fourth Issue, September 2002 81

1. Size the generator to the load.

2. Size the cord to either 100% or 115% of the rated generator output.

(NEC 445-5)

3. Have overcurrent protection either in the house or in the generator.

(NEC 445-4)

4. Attach the cord to a receptacle body (Do not use a plug.) and wire the

house connection with a flanged inlet. (NEC 410-56(g))

5. In the house, connect the wire from the flanged inlet to the standby

side of a manual disconnect switch. (NEC 225-36)

6. Supply the transfer switch with a normal feeder from the house panel,

sized and protected per NEC 215-2(a) and NEC 215-3.