Safety First: If you are adding a generator for Y2K or other emergency power needs to your present power supply, you must follow all local, state, and national electrical code requirements. One of the most commonly overlooked safety devices is a TRANSFER SWITCH. A transfer switch is required by the National Electrical Code (NEC) and is used to isolate the utility electrical supply from your generator. If this is not done, your generator can backfeed into the utility lines causing serious injury or death to you, your neighbors, or utility work crews.

In addition, always read and understand the manufacturer's instructions. Properly ground your generator per manufacturer's instructions and local electrical codes. Also remember, generators use fuel to operate. Proper ventilation is required for exhaust fumes, and never re-fuel the generator while running.

Proper Sizing: This is probably one of the most confusing topics of the year. Franklin has recently been in contact with some of the most popular generator manufacturers to ask them the necessary specifications for proper generator sizing. According to the information we received, the most important requirements for proper sizing are 1) Identify what items you want to run. 2) Check the start/run watts required for each item. 3) Total the start/run watts for all items and select a generator that exceeds your total start/run watt requirement. Sounds pretty simple. So where does the confusion come in?

Confusion: The first point of confusion results from the generators being rated in watts while the motor nameplates list “max amps”. The generator watt rating is actually a volt-amp rating. Therefore, we can simply multiply the motor max amps times the rated voltage from the motor nameplate to determine the load of the motor. Household size motors have been calculated for you in the table on the next page.

A second point of confusion is the starting amps of the motor are much higher than the running amps. In a submersible motor, the duration of the starting amps is only ½ second, but the generator must be able to supply these amps to properly start the motor. Generally, the motor starting amps determine the size of the generator. We list the starting amps, under locked rotor amps, in Franklin's Application Installation Maintenance (AIM) manual, and tabulate the volt-amps of the most popular ratings in the table on the next page.

Generator Sizing: The first step is easy: identify what items you want to run. These are typically lights, heat or air conditioning, refrigerators, freezers and water pumps. Some of these items will only run once in a while but you need to account for these intermittent loads per the generator manufacturer's recommendations.

The second step: check the starting watts and running watts for each item.

The third step: total the starting watts and total the running watts, then select a generator according to the manufacturer's recommendations. Generator manufacturers typically list two (2) watt values in their literature. The first is the running load, while the second is the starting or “surge” load. The running load is the continuous watt demand necessary to keep your electrical device running. The starting load is the temporary high power demand needed for initial start-up.