Train your construction crews to safely use portable power to avoid construction accidents 

Contractors working on commercial jobsites depend on the power delivered by generators to keep projects on schedule. Selecting the right generator, maintaining it and using it safely all result in a job well done. 

Following a simple routine maintenance schedule ensures the safest use and longest life from a generator. 

Preventive Maintenance 

Before a portable generator can be used safely, it should be in good working order. Preventive maintenance begins with monitoring oil and air—two crucial factors in efficient generator operation. 


The oil level for a generator, especially those used in commercial applications, should be checked daily and when adding gasoline because many generators have single-cylinder, air-cooled engines that tend to consume more oil than those in vehicles. 

These 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 combustion chamber. To keep the generator running smoothly and prevent breakdowns, the oil should be checked frequently. 

The condition of the generator’s air filter should be monitored for commercial generators that operate in dirty or dusty environments. With each use, the filter should be cleaned regularly (daily in very dusty environments) because a clogged air filter could quickly lead to overheating and a breakdown. 

For more detailed maintenance guidelines, refer to the generator’s shop manual, a useful reference guide that provides troubleshooting procedures for all common problems. 

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. 

Safety Guidelines


Besides knowing your own commercial model inside and out, keep these tips in mind:

For proper operation, the model should be placed in an open, well-ventilated space and at least 3 feet away from an occupied building. To avoid the risk of carbon monoxide poisoning, the generator should never be operated in an enclosed area. 

Portable jobsite generators must be transported safely. The fuel petcock and vent cap should be closed tightly before moving the unit to prevent fuel leaks.  

Before using a generator, it should be properly grounded. Every unit has a grounding lug, which should be connected to a ground rod. For specific grounding regulations, check your local requirements. 

Portable generators should never be operated near dry gas or other flammable materials because they can get hot enough during normal operation to create a fire hazard.


To minimize the risk of electric shock, the generator must stay dry and sit on a firm, level surface while running. 

A generator connected to a building’s electrical system must be connected through a transfer switch. This switch breaks the connection to the electric utility company 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.

A generator should never be refueled during operation. Also, spilled fuel may ignite, so spills must be cleaned immediately.

The generator’s maximum output capacity should not be used for more than 30 minutes at a time. Continuous operation should not exceed the rated load. Refer to your owner’s manual for additional specifics. 

A generator should not be overloaded repeatedly. Even though the breaker will trip, it has a time delay to allow starting electric motors. 


If the breaker keeps tripping, other tools should be unplugged (or you may need a generator with more power output). 

Construction Business Owner, May 2012


A Generator Maintenance Checklist

  1. Every three months or 50 hours: Clean the air filter.
  2. Every six months or 100 hours: Change the oil, check spark plugs and replace them when necessary, clean the spark arrestor screen and clean the fuel filter.
  3. Every 12 months or 300 hours: Replace spark plugs, adjust the valve clearance and adjust the idle speed.
  4. Every 500 hours: Clean the combustion chamber.