Generators on the Job

When it comes right down to it, grounds care is all about maintaining beautiful environments. Whether you supervise the grounds for a golf course, are a contractor for a landscape company or are in charge of the grounds for a fixed site such as a bank or an office building, the common denominator for achieving a luscious, green expanse is having the right lawn and landscape tools in your arsenal.

The obvious power equipment products that come to mind are commercial lawnmowers, tillers, trimmers and even pumps. But don't forget about the important role a generator can play in grounds maintenance. From pond aeration to nighttime construction at an office park to cooling golf greens with fans — all of these activities require dependable, portable power. Enter the portable generator.

The first step for every grounds maintenance professional is to choose the right generator for the job. Equally important is conducting the preventative maintenance that ensures these portable powerhouses start every time and run dependably without costly, time-consuming breakdowns.

The selection of the right commercial generator for the job starts with answering a few basic questions: How will you use the generator? How quiet do you need it to be? Do you require electric start? How easy does the transport of the model need to be? How much power do you need to do the job?

“The answers to these basic questions should be guidelines in selecting any generator,” says Clay Yeatman, senior engineer at Honda Power Equipment, a division of American Honda Motor Co, Inc. For instance, in looking at portability, many models include standard wheel kits for easy movement of the generator from storage to the work site. Consider the options when selecting the right model for your application.

“Once you have the power you need, preventive maintenance is the real key to a smart start on the jobsite or for a commercial rental application,” Yeatman notes. “Routine preventive maintenance not only provides the most reliable start, but it also helps ensure maximum service life of any generator.”


Always remember that simple power management will allow a smaller generator to do a big job — very seldom do all tools or appliances operate simultaneously. When calculating power requirements, consider the starting requirements are only for the initial start and then additional tools may be operated.

Remember Ohm's Law from High School Physics?

Watts = Volts × Amps
Amps = Watts/Volts

If you have two of the numbers (e.g. volts, amps), then you can calculate the other (e.g. watts). A number of different resources online can help you to determine the rated power that you'll need from your generator. Look for a site that also provides a wattage calculator, a guide to the power requirements of many appliances and tools (see the following chart for commercial wattage specifications) and other information on generator safety.


“A little common sense goes a long way when using any type of generator,” advises Yeatman. In addition to knowing your own commercial model inside and out, keep in mind these cautionary dos and don'ts:

  • For proper operation, make sure your model is placed in an open, well-ventilated space. In other words, never operate the generator in any type of enclosure to avoid any risk of carbon monoxide poisoning. Right now, this issue is a key focus area for The Consumer Product Safety Commission because of the widespread use of generators following last year's natural disasters.

  • All generator alternator windings and engines need a good flow of cooling air, so remember not to operate the generator within 3 feet of any wall. What are the worst possible resulting scenarios? It might result in your need to rebuild the engine or replace the rotor/stator (in this case, it is less expensive to just buy a new generator).

  • To minimize the risk of electric shock, keep the generator dry and on a firm, level surface while running.

  • Don't forget to run (exercise) your generator at least once a month. This accomplishes a couple of things. It lubricates the engine by circulating oil, it runs fresh gas through the carburetor and it works to recharge the battery. All of these things help to ensure that the generator will start when you really need it.

  • If you will not use the generator for a month, drain the fuel tank and carburetor float bowl. Otherwise, the fuel may evaporate and cause gumming of the small passageways, which will require you to take the generator to a dealer for carburetor cleaning or replacement.

  • If you are connecting your generator to a building's electrical system, you must connect through a transfer switch. This switch breaks the connection to the electric utility company first and then makes the connection to the generator. Without this switch, when the utility power comes back on, it will feed back into the generator and overheat the windings — necessitating a costly repair. Or even worse, a worker repairing the electric lines would be exposed to high voltage from the generator as its output is stepped up if it is fed back through a transformer.

  • Never refuel a generator while it is running. Spilled fuel may ignite, so wipe up any spills.

  • Be sure not to use the maximum output capacity of the generator for more than 30 minutes at a time. Continuous operation should not exceed the rated load (generally 90 percent of maximum load, depending on the cooling system). Again, refer to your owner's manual for additional specifics.

  • Do not repeatedly overload a generator. Even though the breaker will trip, it has a time delay to allow starting electric motors. Repeated overloads may degrade the insulation on the windings over time, and it can be expensive to replace the rotor and stator.

  • If the breaker keeps tripping, unplug some tools or get a bigger generator.


Preventive maintenance begins with monitoring oil and air — two crucial factors in efficient generator operation. On any generator, and especially those used in commercial applications, it's most important to check the oil level daily, as well as every time you add gasoline. This is because many engines on generators have single-cylinder air-cooled engines that tend to consume more oil than those in other vehicles, such as cars and trucks.

These kinds of engines may see more dimensional changes as the load on the generator fluctuates and thermal expansion occurs. Oil is consumed because the crankcase volume changes as the piston moves up and down, enabling oil mist to travel through the breather into the intake port and ultimately the combustion chamber. To keep the generator running smoothly and to prevent breakdowns, check the oil frequently. Another good rule of thumb for commercial generators that operate in dirty or dusty environments is to monitor the condition of the generator's air filter.

“A clogged air filter is a shortcut to overheating and a breakdown, so with each use, be sure the filter is clean and clear,” advises Yeatman. “It may even need to be cleaned every day in dusty conditions.”

For more detailed maintenance guidelines, refer to the generator's shop manual that came with your model. The manual is a handy reference guide that provides troubleshooting procedures for all common problems. Generally, a normal maintenance schedule includes the following routine best practices:

  • Every three months or 50 hours: clean the air filter.

  • Every six months or 100 hours: change the oil, check the spark plug and replace it if fouled, clean the spark arrestor screen and clean the fuel filter.

  • Every 12 months or 300 hours: replace the spark plug, adjust the valve clearance and adjust the idle speed.

  • Every 500 hours: clean the combustion chamber.

For anything beyond routine maintenance, play it safe and take the generator to a dealer. A person conducting a running test of a generator could be exposed to 120 or 240 volts of electricity, which could be fatal in certain conditions.

“Even if the generator is shut off, a generator with a condenser [capacitor] can give you a nasty shock,” says Yeatman.


Along with routine maintenance checks, it is important to keep an eye on your generator's major wear items. Many commercial generators come equipped with automatic voltage regulators (AVRs), which have brushes to vary the excitation of the rotor. The AVR controls voltage very accurately at different loads, but the brushes can wear prematurely if dust gets on the slip rings on the rotor. The result is likely to be erratic output or no output whatsoever.

“The best way to stay ahead of real problems is to consult your generator's shop manual which cites wear-limit dimensions for the brushes,” says Yeatman. “There usually is no standard schedule for checking the brushes, but most rental shops will check them periodically. Replacement brushes are fairly inexpensive and they are easily replaced by removing the end cover of the alternator.”

In addition, it's a good idea to routinely check the generator's valve clearance. Left unmonitored, the clearance can become too large and the recoil starter may become hard to pull. This is because the automatic compression release on the camshaft is no longer able to operate. The fix is to adjust the valve clearance.


“Having a thorough understanding of your power requirements is the most important factor in selecting the right generator for your job requirements,” explains Yeatman. “Following a simple routine maintenance schedule will help you get the smartest starts and the longest life from your generator.”

Kristen Delaney is manager of marketing and product planning for Honda Power Equipment, a division of American Honda Motor Co., Inc. (Alpharetta, Ga.).

Contractor Running Wattage Requirements Additional Wattage Required for Starting
Air Compressor, 1 hp 1,500 4,500
Bench Grinder, 8 inches 1,400 2,500
Hand Drill, ½ inch 600 0
High-Pressure Washer, 1 hp 1,200 3,600
Circular Saw, Heavy Duty, 7.25 inches 1,400 2,300
Electric Chain Saw 14 inches, 2 hp 1,100 0
Table Saw, 10 inches 1,800 4,500
⅜ inch, 4 amps 440 600

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