Commercial Generator Maintenance: How Much Does It Cost?

Tucked away in a basement or outbuilding, it can be tempting to forget all about your generator until the power goes out—but like any other piece of large equipment, commercial generators need to be properly maintained to ensure they will work when you need them to.

If you own or oversee a commercial generator system, it’s important to understand what kind of maintenance you’ll have to do to keep it ready for use and prolong its life.

It’s also important to understand maintenance costs, which will depend on a variety of factors such as engine size, fuel type, and the kind of maintenance that needs to be performed.

Here’s what you need to know about commercial generator repair and maintenance.

How Long Do Commercial Generators Last?

In general, a commercial generator with a diesel engine will last between 10,000 and 30,000 hours of run time. To put that into perspective, car engines typically last around 5,000 hours. This means you can get 30 or 40 years of use out of your commercial generator provided you properly maintain it.

How long a generator will last depends partly on what type of engine it has, which also affects maintenance costs. In general, commercial generator engines are categorized by size and fuel type.

Engine size

Like car engines, a generator’s power is measured in horsepower. More horsepower means higher power generation potential. It also means a bigger physical size and higher fuel consumption.

When purchasing a commercial generator, it’s important to choose the right size. Too much power can be almost as bad as too little, so bigger isn’t always better. An oversized generator never runs at full capacity, creating a variety of problems like wet stacking and carbon buildup that reduce the engine’s lifespan.

If you’re looking for a commercial generator, find a generator service provider like Electromotion with experts who can help you select the right engine for your business.

The other way that commercial generators are classified is by fuel type, and this also has implications for maintenance costs.

Diesel generators

The most popular type of commercial generator, diesel engines are known for their power, durability, and efficiency. In general, they are reliable and easy to maintain and repair. Some disadvantages of diesel generators are that they tend to be large, noisy, and produce a lot of emissions. Despite these drawbacks, they are still the most widely used type of commercial generator.

Natural gas generators

Natural gas generators use propane or liquified petroleum gas for fuel. Natural gas is less expensive than diesel, and burns more quietly and cleanly than diesel. However, natural gas commercial generators tend to be higher maintenance than their diesel counterparts, although their life expectancy is about the same. Natural gas is also highly explosive, so the fuel stored on site can present more of a fire hazard.

Gasoline generators

Gasoline-powered generators are usually cheaper than other options up front, but typically require more maintenance on an ongoing basis. The gasoline deteriorates rubber components, causing the engine to wear faster. Storing the large amounts of fuel needed for a standby generator is also more difficult due to its flammability and the fact that gas deteriorates over time.

In general, gasoline generators are not the best choice for larger industrial applications.

Maintenance Checklist for Commercial Generators

No matter what size and type of commercial generator you have, the most important factor that will determine its lifespan cost is how well you maintain it.

Proper maintenance keeps your generator ready to function well during an emergency or outage. If you don’t properly maintain your generator, you’re risking an expensive and disruptive system failure.

Regular maintenance also helps you keep costs down. It helps catch problems while they are still small and relatively inexpensive to fix, rather than waiting until the problem gets bigger and requires more costly repairs.

Proper commercial generator maintenance involves a lot more than just changing the oil or cycling it on every six months. There are a lot of components that require regular upkeep to ensure the system works—and often, many of them get overlooked.

Here’s a basic yearly maintenance checklist for your generator that’s compliant with the industry standards provided by the National Fire Protection Association (NFPA 110):

    • Maintenance inspection (3-12x per year)
    • 2-4 hour load bank test (1x per year)
    • Automatic transfer switch maintenance (1x per year)
    • Fuel testing and tank inspection (1x per year)
    • Insulation resistance testing (1x per year)
    • Annual maintenance (1x per year)

Monthly or quarterly maintenance inspection

At least once every three months, you need to have a specialized service provider perform maintenance on all of your commercial generators.

During this inspection, they should test the unit, inspect the automatic transfer switch (ATS), and go through a detailed maintenance checklist. Learn more about monthly maintenance inspections here.

Load bank test

Once per year, a generator needs to be placed under a full load for an extended period of time, typically two to four hours. This is called a load bank test, and it helps to verify that the generator can operate at full power, as well as to burn off the hazardous excess fuel that accumulates in the exhaust over time.

In many jurisdictions, annual load bank tests are required to maintain a valid generator permit. Learn more about load bank tests here.

Automatic transfer switch maintenance

The automatic transfer switch (ATS) is the critical part of your system that switches your building’s power supply from the grid to your generator in an emergency. You can have the best generator in the world, but if your ATS malfunctions, you can’t access all that power.

Once a year, your ATS should be taken apart, inspected, and tested. Learn more about ATS maintenance here.

Fuel testing and tank inspection

Diesel fuel deteriorates over time—clogging your commercial generator engine, causing poor performance, and damaging components. To prevent this, the fuel tank needs to be inspected once per year, and fuel needs to be filtered or replaced once every two years. Learn more about fuel maintenance here.

Insulation resistance testing

Insulation resistance testing is a specialized procedure used to identify weaknesses in the electrical components of your system that would be undetectable under normal conditions. During the test, your service provider will apply voltage to the alternator windings to determine if the insulation is damaged and may cause a short circuit under normal operation.

It helps prevent total system failure, and needs to be performed once per year. Learn more about insulation resistance testing here.

Annual maintenance

Once a year, commercial generator engines need maintenance that goes beyond the quick tests and inspection list of the monthly visits. You should have the fuel and air filters changed, inspect the automated transfer switch, and send some oil samples to an independent lab for analysis. Learn more about annual maintenance here.

Other maintenance

This isn’t a complete list of everything you need to do to properly maintain your commercial generator. There are other services that only need to be done every two or three years—for example, replacing your battery or servicing your cooling system.

Here’s a full list of the services you need to keep your generator in great shape.

How Much Does Generator Maintenance Cost?

How much generator maintenance costs varies depending on the engine size, fuel type, age, and how well it’s been maintained in the past. Other factors like brand and geographic location affect costs as well.

One thing is for sure—no matter what kind of generator you have, keeping it well maintained is much cheaper than neglecting it. Not only are you risking a dangerous and disruptive unit failure when you need your generator most, but over time, you’ll spend more on maintenance as routine repairs deteriorate into expensive problems.

To get a quote for your business, find a generator service company in your area you trust. If you’re in the Bay Area, we’d love to help!

At Electromotion, we have 50 years of experience designing custom maintenance plans for any backup power system, on just about any budgets. We’ve worked with some of the biggest companies in Silicon Valley, the US government, and even NATO, as well as hundreds of smaller businesses.

All our maintenance is performed by EGSA-certified technicians with a minimum of 100 hours of safety and skills training per year, and we are available 24/7, with a maximum two-hour response time for emergencies.

Schedule a consultation with us today.

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