How to Compute Amps on the Low Side of a Utility Power Transformer
- 1). Estimate the input voltage to your home or business to be 230 volts. Most homes have 220 to 240, but a few older homes still have 110 to 120. If your home or business can't have an outlet for an electric stove or dryer, you probably have between 110 and 120. Or check it with a voltmeter at any wall socket--if a voltmeter is available and you know how to use it. But the 230 figure should be close enough.
- 2). Add up the power in watts of all the items in your home or business that use electricity. Every electrical appliance should have a tag showing how many watts it draws.
- 3). Divide the number in step 2 by the number in step 1. For example, you have 230 volts house wiring, and you added up 7,500 watts of equipment in your home, so 7,500 divided by 230 equals roughly 32.6 amps.