Many modern apparatus have large, built-in generators to provide electrical power for lights, equipment and tools at incident scenes. This is an effective way to put a generator in operation quickly with a minimum of personnel. Despite this trend, there still are many situations where smaller, portable generators can be of great value.

Portable generators can be handy in situations where power is needed beyond the reach of most cord reels, for example, at remote rescue sites such as over-the-side vehicle extrications or back-country rope rescues. Portable generators also can provide emergency power to evacuation centers, gas stations, city buildings, or other key facilities during storms to keep apparatus free to respond to other incidents.

Here are some practical points that departments should consider when specifying portable generators:

Power ratings. Generators have two power ratings. The maximum rating is the power in watts that the generator can produce for a short period — usually about an hour or less. The continuous rating is somewhat lower than the maximum, but the generator can operate for extended periods at this output. Use the continuous rating when selecting a generator to meet your power needs.

Weight. The lighter the generator, the more places you can take it. Some models can be lifted by a single person. Others require two or more persons. Wheels can help move heavier generators on hard surfaces, but they are of limited value on soft or muddy ground. If you carry the generator on an apparatus, place it in a lower compartment and install a slide-out tray to facilitate its removal.

Run time. Generators with small fuel tanks can run out of gas in the middle of an incident. Most generators should have large enough tanks to provide two to three hours of run time at continuous loads. Some are designed to provide five to eight hours of operation. Departments that use generators during long-term incidents should consider selecting models with larger tanks and extended run times.

Transfer switches. Using a generator to provide power to a building usually requires a professionally installed transfer switch to safely disconnect the building from the power grid and connect it to the generator. Failure to do this can inadvertently sent power back through the outside power lines and potentially cause fires or electrocute someone.

Power cords. Distributing power from a generator requires heavy-duty power cords designed for outdoor use. Cord reels provide an easy way to store and unreel the cords. Junction boxes allow a single power cord to run several electrical devices. Always match the power cords and junction boxes to the generator output.

Noise. The constant roar of a generator can hinder communications at a busy incident scene and can add to the stress level of injured persons. Some generators are designed to produce very low noise levels. If possible, ask for a demonstration and judge the noise before you buy.

ISO Rating. The Insurance Services Office will give credit for a generator as part of a service or truck company's loose equipment. To gain full credit, the generator must be rated at a minimum of 2,500 watts and must be brought to every structure fire. Additional credit is available for a minimum of three 500-watt floodlights.

Maintenance. Generators need maintenance just like any other piece of equipment. When you purchase a generator, get the operation and maintenance manuals as well. Also determine the location of the closest parts and service center. Add the generator to your preventive maintenance schedule and keep a record of all inspections and work performed. Ensure the persons performing the maintenance are properly trained.