Trying to figure out how much current my attic fan draws and the label is scratched off
how many amps it pulls will ultimately depend on whether it is shaded pole, permanent split capacitor or split phase...a 1/5 hp motor will be about 150 watts..if one horsepower is 745 watts..then divide 745 by 5 and that gives you the wattage of the motor...or about 149 watts...divide watts by volts 149 divided by 120 volts is 1.4 amps..a psc motor will be little less than a shaded pole and a split phase will be more than a shaded pole.. nsdiering this is an attic vent direct drive fan motor(not belt driven) it is probably a shaded pole motor..
Depends how efficient the motor is. At 120 V it could draw anywhere from 80MA to 8A depending on if the motor draws 1000 Watts or 10 Watts. Probably draws around 50 Watts which would put it at 410 MA or about a half an Amp. You can by the way make it way more efficient just like any AC motor by placing a capacitor over the Hot and Ground.
The horsepower rating is a measure of the motor's output power. That doesn't say exactly how much current the motor draws to generate that power. If you can find a wattage rating on the motor, you can take watts and divide by 120 to give you the amperage. Typical full-load current draw for a motor like this would be anywhere in the range from 1.0-2.5 Amps. Depends on efficiency of the motor, rpms, size of motor, how much load you're putting on it, etc. Probably you already know that typically the current draw is very high (peak) on startup and then comes down after the motor is at running speed. If you're just concerned about the peak (startup) load, you're pretty safe with figuring less than 6 Amps. If you are looking for a replacement motor, and if you can find a supplier name and part#, then a good motor supplier will be able to help you cross-reference to an equivalent new motor. You'll also want a motor with the same form, fit, and direction of rotation, etc so you can just swap it out. Good luck!
In my electronics class we were taught that 1 Hp. is equal to 745 watts or roughly 6.2 amps. A half Hp. would be half that. NOW LISTEN CAREFULLY: Any figures for motors that you derive through anything but actual testing are only rough guesses. There are different ways to make motors and any number derived through calculations is just an educated guess. It, the calculated number, ignores all environmental issues as well as friction and who knows what else. Does that help??
