Portable Generator Basics

An XP10000E at an outdoor event.

The Generac XP10000E ready to power an outdoor community event.

Portable generators supply electrical power wherever it is needed. Construction sites use them to power electric tools and temporary lighting. Quiet generators in campsites power small appliances and festive lights. Homeowners use them for outdoor equipment or backup power during an outage. RV owners power their home away from home.

Small portable generators capable of 1200 to 3500 watts are popular for camping and outdoor fun. At the other end of the spectrum are models like the Generac GP17500E, rated for 17.5 kilowatts of continuous power and up to a 26.25 kilowatt surge—suitable for large job sites or keeping the lights on during a power outage.


IQ2000 Inverter Generator lifts easily into the back of a pickup truck.

Small, easy-to-carry inverter generators go from tailgating and camping to supplying emergency power at home.

Small, quiet inverter generators allow single-handed carrying from location to another. They weigh as little as 30 pounds and run for up to 10 hours on a single tank of gasoline. They are built mainly for consumer use with the largest producing up to 3400 watts of continuous power.

Some even have USB ports for charging your electronics.

Larger gas portable generators are mounted on two-wheeled carts and are moved in fashion similar to a wheelbarrow. They can weigh hundreds of pounds, but are balanced on the wheels to allow one person to easily move them. Rated continuous watts begin at around 1800 and include both consumer and commercial models.

Power Outlets

Receptacles and circuit breakers on the GP17500E

Outlets on the GP17500E (50-Amp 240-volt Receptacle and Circuit Breaker Not Shown)

Portable generators can supply power as 12 volts DC, 120 volts AC, or 240 volts AC, but not all models are capable of supplying all three, and some only provide 120 volts AC.

Duplex (double) outlets are common on portable generators and each one supplies 120 volts. Ground fault protected outlets (GFCI) are a feature on some models and protect the user from electric shocks.

120/240 volt outlets provide a way to connect the generator to a circuit breaker panel with a connection to two, 120-volt terminals, a neutral terminal, and a ground wire. To obtain the full 240 volts, both 120 volt terminals are used. This is exactly how the main service panel in a home works, making it possible to power the house during an outage through a generator manual transfer switch.

Some models have a 12-volt outlet suitable for charging a battery or operating a 12-volt appliance.

Circuit Breakers

All electrical outlets are required to have circuit breaker protection rated at or below the maximum current-carrying capacity of the outlet and outlet wiring. Each outlet or duplex outlet on a generator will have a circuit breaker associated with it.

Main circuit breakers are designed to protect the generator against overload. They will handle a momentary surge that exceeds the breaker rating, but if the high current continues, the breaker trips and all the outlets stop working. On generators with only one or two outlets, the main circuit breaker sometimes acts as the outlet breaker. Since the outlet is rated at 1800 watts, the main breaker protects the outlet and the generator at the same time.

Electrical Ground

An important safety feature is the portable generator’s electrical ground. It provides a path for electrical current to follow back to the source in the event of a short circuit. A grounded appliance routes power through the easiest path for electricity to follow. If a short circuit occurs, electricity follows the ground instead of passing through a person.

Often, the neutral on a portable generator is bonded (connected) to the frame and to the outlet ground terminals. Current can then flow back to the generator in case of a short. Read your owner’s manual to understand how your ground is connected and if your generator requires removal of the bond to connect it to your home.

Portable generators offer a great source of power for many uses. Advances in technology have increased efficiency, portability, and power output, and made them available at a cost affordable to many consumers in sizes to fit a myriad of needs.

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