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bzitser · Mar 5, 2007, 02:09 PM

Can 20 Amp. Ciruit Breaker Support 1 Hp 115 Volt Single Phase Motor?

Robair · Mar 5, 2007, 02:26 PM

Yes It can... However, The breaker is overrated for the application.
So look at the specs on the motor carefully... But by and large you should have a 15Amp breaker.
It's suppose to trip when under heavy load to protect you. If you use a 20 A unit... the motor and wires can overheat and created unspeakable damage.
Get a 15Amp breaker.
Good luck;)

bzitser · Mar 5, 2007, 09:42 PM

Originally Posted by bzitser

Can 20 Amp. Ciruit Breaker Support 1 Hp 115 Volt Single Phase Motor?

Thank's Robair for your respond, but to my knowledge I have to size single phaze breaker minimum 20% above that total amperage draw by motor and 1HP whisperflo swimming pool pump(what I want to install) has full load 14,8 amps.
If I am right, my qwestion still stay .Please respond.
Sinserely yours
bzitser.

tkrussell · Mar 6, 2007, 02:57 PM

Almost correct, a 1 HP motor 1 Phase motor branch circuit and short circuit protection needs to be rated 125% of the value listed in NEC Table 430.148, which for 115 volts is 16 amps, so minimum size rating of a breaker is 20 amps.

An inverse time circuit breaker can be sized up to 250 % of the rating in Table 430.148, depending on several other factors that may not apply, since this is only a water pump.

Overload protection, if needed, will only use the nameplate rating of 14.8 amps, and again may or may not be required depending on other factors.

ColGrayBeard · Mar 8, 2007, 08:21 AM

Yes.

A 1 HP motor draws about 13A at 120VAC. You should make sure that your wiring will support this load as well. Although # 14 would support 13A, the start-up current will be higher than 13A. You should wire to the motor with # 12 wire.

ColGrayBeard · Mar 8, 2007, 08:39 AM

Yes.

A 1 HP motor draws about 13A at 120VAC. A 20A branch circuit breaker would be appropriate. You should make sure that your wiring will support this load as well. Although # 14 would support 13A, the start-up current will be higher than 13A. You should wire to the motor with # 12 wire.

I just saw the information about the 14.7A nameplate rating. The same answer applies with the slightly higher rating.

Based on my experience, using a 15A circuit breaker will result in a significant number of nuisance trips. The motor should have internal thermal protection to protect from overloads.