HI,
I have a small shop space with single phase run to a 100amp breaker main, and I bought a few items such as a welder, plasma cutter and a compressor. In order to ensure I select the correct breaker for these devices and any other ones in the future, I was wonder if there is a formula or table/chart that one can use to determine the correct breaker size to use for each said item? For instance the comprossor states 240v/ 60 Hz/15amp. IT has a 3.7 HP motor. What formula or process does one use to determine the the correct breaker/wire/outlet size needed? I've read that for each 1 HP = 745.7w, and in the case of the compressor specs, I multiplied 745.7 x 3.7 = 2759.09 and then divide that by the 240v mentioned on the compressor in order to determine the amps. But that only gives me 11.49 amps. Which to me makes no sense on why one would need a 30 amp dual pole breaker. Basically I want to know what the a rule of thumb is which allows one to determine the breaker size, outlet size, and wire size for a device based on the specs printed on the device.
I have a small shop space with single phase run to a 100amp breaker main, and I bought a few items such as a welder, plasma cutter and a compressor. In order to ensure I select the correct breaker for these devices and any other ones in the future, I was wonder if there is a formula or table/chart that one can use to determine the correct breaker size to use for each said item? For instance the comprossor states 240v/ 60 Hz/15amp. IT has a 3.7 HP motor. What formula or process does one use to determine the the correct breaker/wire/outlet size needed? I've read that for each 1 HP = 745.7w, and in the case of the compressor specs, I multiplied 745.7 x 3.7 = 2759.09 and then divide that by the 240v mentioned on the compressor in order to determine the amps. But that only gives me 11.49 amps. Which to me makes no sense on why one would need a 30 amp dual pole breaker. Basically I want to know what the a rule of thumb is which allows one to determine the breaker size, outlet size, and wire size for a device based on the specs printed on the device.