Yahoo Answers is shutting down on May 4th, 2021 (Eastern Time) and beginning April 20th, 2021 (Eastern Time) the Yahoo Answers website will be in read-only mode. There will be no changes to other Yahoo properties or services, or your Yahoo account. You can find more information about the Yahoo Answers shutdown and how to download your data on this help page.
1hp requires how many amps?
1hp at 120 volts requires how many amps
- .Jerry.Lv 72 months ago
"1hp requires how many amps?"
A lot of good answers here already. But just remember one thing. HP is an output power rating. So the measure of 1HP is 746 watts. But note that it will take more than 746 watts of power input in order to get 1HP output because of inefficiencies and power factor. After this you can use Watts Law & Ohms Law to work your way to a solution on how many amps will be drawn at full load.
- Anonymous2 months ago
At what voltage?
The scientific formula is 746 watts per horsepower.
746 ÷ 120 = 6.2 amps
Add some more current for electrical and mechanical and magnetic inefficiency.
Also, the starting current of a typical single phase induction motor of that size is 2 to 3 times the running current.
So make sure you use a 20 amp switch and a 20 amp branch circuit.
I would use no more than a ¾ horsepower motor on a standard 120 volt, 15 amp branch circuit; especially for an air compressor.
- JoeLv 42 months ago
Depends on the specs for the electric motor. A 115 volt, 60 Hz, 1 Phase electric motor needs 13.0 amps doing 1,075 rpms for 1hp.
- ?Lv 52 months ago
That depends on the winding! A 6-volt motor would require more amps to run it than a 12-volt motor and a 120 volt motor would require less still a 240 volt motor still less
- How do you think about the answers? You can sign in to vote the answer.
- MorningfoxLv 72 months ago
120 volts * 6.22 amps = 746 watts = 1 hp
... assuming that the voltage and amps are in phase, which is rarely the case for a motor.
- billrussell42Lv 72 months ago
depends on the voltage. and number of phases and efficiency.
1 HP = 746 watts
BUT, the 1 HP is output power, not input, you have to factor in engine efficiency. Say 80%, then input power is:
1 HP = 933 watts input power
at 120 volts, that is 7.8 amps
at 240 volts, that is 3.9 amps