The website you are trying to access is not compatible with Internet Explorer. Please use Microsoft Edge to ensure an optimal browsing experience.

Does your generator run under loaded?

17 Aug, 2016

No one wants to invest in their equipment more often than they have to in order to keep it running optimally. That is why running backup generators efficiently is important. It helps prolong the life of the machinery and keeps them operating well. Running a generator under-loaded is like idling your car for six months and then one day pressing on the accelerator and expecting it to go from a standstill to 60mph smoothly. It may not happen!

When generators are not maintained and loaded properly, they can be the cause of unplanned downtime, increased operating costs from excessive fuel consumption, undue wear, and increased emission outputs.


All generator sets, whether diesel or liquefied petroleum gas such as propane (LPG), regardless of application, load settings, and operation, are designed to provide power in the most efficient manner possible. As such, every generator set will have an optimal workload-to-fuel-consumption sweet spot. Because different engines consume fuel at different rates, and higher workloads almost always burn fuel most efficiently, diesel generator efficiency is usually achieved at the higher end of the load setting the generator was designed to maintain. A 15kw residential generator, for instance, may have lower fuel consumption operating at 10kw rather than at 6kw.

One of the most prevalent problems with diesel engines running below their designed load capacity for extended periods of time is the phenomenon known as “wet stacking.” Wet stacking occurs when unburned fuel is exhausted due to low operating temperatures. When unburned fuel is exhausted from the combustion chamber, it starts to build up in the exhaust side of the engine, resulting in fouled injectors and a buildup of carbon on the exhaust valves, turbocharger, and exhaust.

To avoid wet stacking and other problems resulting from running your generator on a light load, it’s important to run your generator within its optimal range as often as possible. Here are some commonly accepted best practices for achieving diesel and LPG generator efficiency.


  • Standby diesel generators – These generators are usually optimized to run at 50-80 percent of the total load rating
  • LPG sets- Regardless of application and rating, LPG generator sets are almost always optimized to run between 70-100 percent of the total load rating.

Running your generator on a light load for extended periods of time will have an impact on the health of your equipment. It is likely to lead to unscheduled downtime, higher maintenance costs, increased fuel efficiency, and an overall shortened service life for the generator.

At Corporate Electric we recommend putting a load bank on your generator to bring it up to temperature and clean out any fuel deposits thus restoring it to a better state. Contact us for more information.