Credit: Multiquip Inc.

For long-term jobs, containerized generators can deliver up to 2 mW of power.

Credit: Multiquip Inc.

Gas-powered generators are portable, versatile, and suitable for powering everything from light towers to drills and saws. heaters and air conditioners. Most can easily be transported to, from, and around any jobsite.

If anyone questioned the importance of having back-up power handy, the abnormal flurry of hurricanes in 2005 provided the answer. Communities throughout the Southeast and Gulf states went days, weeks, even months without power. To complicate matters, generator manufacturers often couldn't make their product fast enough, let alone deliver it, to the hardest-hit areas. Stocking generators should be right up there with water, food, and medical supplies in any first-aid action plan.

With that in mind, how do you go about choosing the correct power source for the job, whether for disaster recovery, fueling a construction site, or driving a water treatment facility?

The primary consideration when selecting a generator is whether it will meet all the operating requirements of the application. This sounds elementary, but all too often the user is offered—and settles for—a product simply because it is on special or it's all that the dealer has in stock.

When determining if a generator is needed to complete the job, there are many variables to consider. The equipment should be flexible enough to allow for multiple voltage taps and output currents. Site requirements vary and the capability of the equipment to handle these demands is crucial.

To maximize the durability and the duty needed from a generator, note the maximum horsepower of the generator's engine and the horsepower at rated load to accurately compare units. For alternators, compare the kilowatt size and heat rise temperature rating to realize the amount of copper and iron in the alternator end of the generator. Copper is the most cost-effective electricity conductor, so generators using 100% copper windings will supply superior voltage regulation and cleaner power. Thus, both the generator and any tools it powers will run more efficiently and last longer than those with units relying on alternators combining copper with other metals.


Professionals using a generator for the first time might be unsure what unit is best suited for their application. Inductive loads require more power to start than to keep running. This typically includes electric motor loads such as power tools, pumps, and air conditioners. Know ahead of time whether the generator will be used to power electric motors—-it simplifies the sizing process.

The amount of power needed to run the load should be a maximum of 80% of the generator's output. Some units are rugged enough to endure years in the field; others are designed price-consciously for occasional use. It is important to decide on the duty the operator will expect from the generator. Output capabilities such as multi-voltage capability, convenient voltage selector switches, and the number of receptacles also are important considerations. Most are standard features on any generator.

Most importantly, understand that you get what you pay for, so compare alternator and engine specifications, controls, and sound levels to ensure a quality product purchase.