Choosing the Right Generator for the Job

Portable generators provide electricity to even the most remote projects. But just as not all jobsites are alike, not all generators suit all jobsites.

To choose the best generator for your needs, there are three factors you’ll want to consider: wattage, decibel rating and fuel source.

Wattage (starting and operating)

The wattage required depends on what tasks or pieces of equipment need to be powered.  Tools and other items construction crews are mostly likely to use display the wattage they take to operate right on their bases or bodies. For example, a table saw would need a generator that can put out at least 1,800 watts. Add to that a few power drills that use 600 watts each, and that ups the required wattage to 3,000.

There are some pieces of equipment, however, that need more wattage to power up — aka starting wattage — than they do to run. A 0.5 horsepower sump pump, for instance, might be able to operate on 1,050 watts but could need anywhere from 2,150 watts to 4,100 watts to start. Generators will typically display their starting wattage capabilities alongside their maximum running wattage.

Decibel rating

In addition to wattage, most generators come with a decibel rating. The National Institute for Occupational Safety and Health (NIOSH) recommends workers be exposed to no more than 85 decibels per 8-hour period (as a time-weighted average), so that should weigh heavily in the choice of a generator if it will be used in close proximity to workers or in enclosed spaces with them.

If workers will be exposed to generator noise for a significant period of time, consider a silenced generator. These are enclosed in an acoustic cabinet. Quieter still is an inverter generator. These run power through an inverter board using advanced electronics and magnets.   

Fuel source

Diesel and gas are the two fuel options. If you’re already using more of one fuel on the job than the other, choosing a generator that uses that same one might be more convenient.

Gas-powered machines are quieter, cheaper and require less maintenance than their diesel counterparts.

Diesel is more expensive right now, but keep in mind that machines can run longer on diesel than on gas. Diesel-powered generators also can work under heavier loads for longer periods of time — they actually perform best under these conditions. Diesel is also less flammable.

To browse available fleet at United Rentals visit our online catalog.

Kim Slowey is a writer who has been active in the construction industry for 25 years and is licensed as a certified general contractor in Florida. She received her BA in Mass Communications/Journalism from the University of South Florida and has experience in both commercial and residential construction.