Generator Specification Sheets – By the Numbers
Looking at a specification sheet and understanding the numbers is second nature. After all, we’ve been factory trained. But for the average consumer reading about generators, things can become confusing and the terminology can be like reading a different language. After awhile instead of becoming informed you just end up with more questions. Maybe if the terminology was explained, the specifications would make sense and become more understandable. Always remember you can email (sales@Norwall.com) or call us (1-855-453-4494) at Norwall PowerSystems with any questions.
Almost all of the automatic standby generator systems Norwall PowerSystems offers operate on either natural gas or propane. These two fuels are slightly different in their composition so for the units that can operate on both fuel types the output is also slightly different, you will see an output rating for natural gas and one for propane. Propane is the higher rating, natural gas slightly lower.
Generator Terminonogy
Btu’s = Natural Gas at 1,000 Btus per cubic foot or Propane at 2,520 Btus per cubic foot. Don’t forget to have your fuel supply and fuel line installed according to local codes and mandates.
NEMA 1 or NEMA 3R = The rating for an enclosure, such as the cabinet on a transfer switch. NEMA 1 is an indoor rating, NEMA 3R is an outdoor rating. There are other NEMA enclosure levels depending on the application. These two are the most common for generators. Automatic Transfer Switch Buyers Guide
Normal Operating Load = Approximately 50% the rated load capacity. For example, a 22kW generator reaches normal load around 11kW.
Rated Power = The maximum output for continuous duty operation. This rating does not include any surge capacity. What can my Standby Generator Run?
Sound Output = The industry standard for measuring sound output levels is 23 feet (7 meters). While specification sheets often list the db(A), the distance at which the measurement was taken is often overlooked. How Loud Are Generator Noise Levels
Surge Capacity = A rating not always published by the manufacture. An authorized dealer can help your installer determine if the unit has enough surge capacity. Surge capacity should only be considered for motor starting amp requirements and never for continuous duty operation. Often referred to as “Starting Watts or Surge Watts“.
Transfer Switch = Safely transfers electrical loads from one power source to another. All standby generators use automatic transfer switches. Portable generator use a manual transfer switch.
