Thoughts to ponder about Generator Replacement

Determining the right time to replace a generator can be a daunting task. A standby generator is one of those pieces of a business that feels useless. Kind of like a Contingency Plan. Until of course the power is out and it is the lifeline to keeping your business functioning or providing critical life safety functions. At CD & Power we are committed to helping you make the most informed decision for your particular requirements.

The first step is evaluating your current system. Trying to come to a consensus on the life of a generator/engine can be a real crap shoot. You can scour the internet and get a lot of different opinions. Here are a couple:

  • Engine life for liquid-cooled 1800rpm engines can approach 20,000 hours if properly serviced depending on the application and environment
  • Even 3600rpm diesel engines normally have a 10,000 to 12,000 hour life expectancy with proper maintenance and service.
  • Diesel engines have a distinct advantage in longevity over their gasoline counterparts. Mechanical parts wear out over time due to the friction caused by parts rubbing together. Diesel engines, however, are engineered and built to be more robust due to the higher compression ratio in the combustion chamber and the high torque output they produce. Diesel engines also operate at lower speeds (rpm) than gasoline engines, which means the bearings, piston rings, cylinder walls, valve train, etc., don’t rub together as often. Engine speeds are often half that of a gasoline engine.

From – The following rules of thumb will prove useful in evaluating the existing infrastructure:

  • UPS batteries should be replaced after six to seven years of service
  • Generator engine life expectancy is 20 to 25 years
  • Transfer switches life expectancy is 20 to 25 years

Here are some factors we suggest you use when evaluating/budgeting for equipment replacement.

What is the equipment usage? At CD & Power, there are over 100 generators in our rental fleet. Engines can go as high as 30,000 hours before experiencing significant difficulties. For most of us, we gauge usage in miles and not hours. Converting hours to miles is helpful in trying to determine replacement intervals for more heavily used equipment and to equate to a marker we more easily understand. This is a very subjective measurement. Estimates for the conversion can be as low as one hour equals 33 miles and as high as one hour equals 60 miles. So as an example, if you have 1250 hours on your generator that would equate to somewhere between 41,250 and 75,000 miles.

What is the impact of air quality regulations today and in the future? Many 30kw generators that were manufactured before 2000 have engines that are over 50hp. Most generators that are 30kw that are manufactured today have engines that are under 50hp and don’t fall under air quality requirements.

How does this generator impact your overall CARB (California Air Resources Board) and/or EPA footprint? What are the emissions now vs. the emissions of the new engine – This is especially relevant for portable generators and fleet averaging. Changing out one high emitting generator can be just enough to get your fleet compliant.

What is the length of time the manufacturer will be supporting parts? The time range for parts support varies from manufacturer to manufacturer. It can be as little as 5 years for smaller manufacturers to 30 years for larger manufacturers. Getting parts that have been sitting on a shelf for 5-10 years can be a real challenge for reliability. The older the generator/engine the greater the chance that the part has been resold or repackaged.

What is the condition of the: engine, generator and controls?

Have there been any major maintenance issues that would impact engine/generator life?

Is the generator oversized or undersized? Running a generator with a light load can lead to carbon build up in the engine and eventually cause damage to the engine. In addition, it can cause you to have emissions that are out of compliance and expose you to fines from air quality. Running a generator with too heavy of a load can have a number of implications. You can cause damage to equipment that the generator is powering due to the voltage/frequency drop. There can also be damage to windings from overloading wires. Most generators have a breaker in place to help lessen the chances of major component failures due to overloading.

Was the generator properly installed in the first place?

Will a new generator require a new cement pad, new conduits, fuel lines, etc.? Costs for removal and installation should be factored into the budget process.

At CD & Power we offer turnkey generator maintenance and installation services. We are the largest independent generator service provider in Northern California. Call us today (925) 229-2700 and let us show you how we are “Powering your Success” or visit us on the web at


Call 866-468-7697 (24/7)