ColKlink,

What are the details? Average elec bill KWH and the high bill's KWh. What else are big electrical users that you have operating? Do you run a standard controller or timer for the irrigation system? How many amps does your controller use? Brand and model of your controller? Aloha

You need to know the cost of your electricity per kilowatt hour. That's 1000 watts over 1 hours' time.

Single phase power usage is calculated by the motor Volts X Amps X power factor. Power factor differs from motor to motor and under various load conditions so use 0.93 as a good average.

As a rule of thumb you can expect to use 1000 watts per horsepower. If you have a 1 HP pump motor and run it 1 hour and you pay 10 cents (0.10) per kilowatt hour then it would cost you 10 cents per hour in electricity to run that pump.