Generator usage is often closely tied to the health of the specific local market as well as the overall state of the economy. As an example, if commercial/industrial construction in a given geographic area is up, while residential construction is down, there are likely many more demands for portable power in commercial/industrial construction than on residential sites. With that in mind, how does a contractor go about choosing the correct generator for the job?

Generator technology, when compared to many other types of construction equipment, hasn't changed much in recent years. Basic generator design has remained the same, while many features once offered as options are now standard, and all of which are designed to give the user more options. And the machines are easier to operate and maintain.

Brushless alternator designs, for instance, are now common since they make a generator essentially maintenance free. Once a costly option, manufacturers and users have demanded it as standard, lowering the cost, as these alternators are now mass produced.

Those improvements, however, don't necessarily translate to the selection process of the most appropriate unit being any simpler. A generator purchaser needs more than just a list of features and benefits to help pick the best unit for the job.

The primary consideration when selecting a generator is whether or not it will meet all the operating requirements of the specific application. It 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 the dealer has in stock.

For contractors, the most important feature on any generator is whether that respective feature is needed to complete the job. Here, there are many variables to consider. The primary need is for the equipment to be flexible in design where it will allow for multiple voltage taps and output currents. Site requirements can vary, and the capability of the power equipment to handle various demands also is crucial.

For operators looking to maximize the durability and the duty needed from a generator, they should note the maximum horsepower of the engine and the horsepower at rated-load to accurately compare generators.

For the alternator, they must compare the kilowatt size and the heat rise temperature rating, to better understand the amount of copper and iron in the alternator end of the generator under consideration. This will give the buyer an excellent idea of the equipment's durability.

Copper is the most cost-effective electricity conductor, so generators using 100 percent copper windings will offer superior voltage regulation and cleaner power. This means both the generator and any tools it powers will run more efficiently and last significantly longer than those with generators relying on alternators combining copper with other metals.

Of course, in a lot of cases, a contractor may be using a generator for the first time, and might be unsure what unit is best suited for their particular application. For them, the basics: operators must use a generator that can provide enough power for the load. Different jobs require different amounts of power defined as reactive or inductive loads. Reactive loads such as lights and computers take the same amount of power to start as they do to run.

In contrast, inductive loads require significantly more power to start than to keep running. This typically includes electric motor loads such as power tools, pumps and air conditioners. Operators should know ahead of time whether the generator will be used to power electric motors—it simplifies the generator sizing process.

The amount of power needed to run the load should be a maximum of 80 percent of the generator's output. Some units are rugged enough to endure years in the field while others are designed price consciously for occasional use. Thus, it is important to decide on the duty the operator will expect from the generator.

Output features such as multi-voltage capability, convenient voltage selector switches, and the number of receptacles also are important to consider for your application. Most are standard on any generator today.

Understand that in generators you get what you pay for, so compare alternator and engine specifications, controls and sound levels to ensure a quality product purchase.

Gasoline generators are typically in the smaller size spectrum of the generator market, that is, 15kW or less. They're best for construction and homeowner jobs to power everything from saws, drills and other power tools to heaters and air conditioners. Most are portable and can be easily transported to, from and around any job site.

Diesel generators are larger, with many manufacturers supplying units in excess of 2 megawatts. In general, diesel-powered generators offer greater durability for longer life, in spite of the lofty price tag. They're good for work on most construction sites, at sporting events and entertainment applications as well as providing back-up power for offices, hospitals and other large structures.

The physical size of a diesel generator usually necessitates it be trailer-mounted for simpler transportation to and from the job site. If a trailer is necessary, ensure that the frame and housing are sturdy enough to withstand extended hours of on- and off-road transportation.

Be aware that not all trailer-mounted generator packages are the same. Note the overall dimensions of the generator before ordering a trailer that just appears to look right. Remember, many job sites have limited access while others have narrow gates, so a failure to specify the correct trailer and generator can be much more than a minor inconvenience.

While at times appearing cumbersome or perhaps too large for the job, diesel-powered units do boast numerous advantages in addition to great power generation. Consolidating the loads of smaller generators into one unit will usually trim maintenance costs, and fuel consumption and noise levels.

Contractors and others considering a generator acquisition would be remiss not to evaluate the environmental regulations in their area. There are government restrictions in all regions for both air and noise pollution, regardless of whether the area is residential, commercial or industrial.

Restrictions vary by state, sometimes dramatically, and can depend on whether the machine is used on a temporary basis or in a permanent application. Operators should be familiar with both local noise and emissions standards, and whether a particular generator has the specifications necessary to comply with those often-stringent government regulations. Failure to do so can result in a resident complaint forcing the user to shut down the generator, adding downtime and cost to any job.

Be sure to check that the generator is adequately equipped for sound silencing. As noted, a generator's sound level is important, so consider how quiet a generator should be in the application and choose the unit accordingly.

Selecting the correct generator for the application isn't an easy process, but by compiling a checklist of what the individual user needs from a unit, the operator will certainly simplify the process.