Swimming Pool Blog

Swimming Pool Pump Motors Deconstructed

Swimming Pool Pump Motors
by Mark Garcia December 16, 2014

Pool Pump Motors Deconstructed

Pictured below is the capacitor start electric motor, made by AO Smith and others, and used to power centrifugal impellers on pool pumps. Capacitor-Start motors use stored powered to give the motor windings additional power, to start the rotor turning. When this power is applied to the coils of wound copper (N) that surrounds the rotor (B), it begins to rotate within the stator. The rotor is alternately repelled and attracted, and this quickly ramps up rotor revolutions to over 3200 RPM.

A. Motor Frame F. Capacitor K. Ground Terminal
B. Rotor and Shaft G. Terminal Board L. End Cap
C. Motor Bearings H. Thermal Overload M. Stator
D. Motor Fan I. Centrifugal Start Switch N. Stator
E. Support Frame J. Governor  

All of the items at the rear of the motor are replaceable, with the capacitor being the most often replaced motor part. Inside the motor, the motor bearings can be replaced if they begin to squeal, although if the motor is over 5 years old, it may be better to replace the motor, in my opinion. Electrical motors are recyclable, and there is some scrap value to the copper windings, if you want to strip them out.


Reading a Pool Motor Label

A. This line gives you the model number of the motor, in this case the UST1102. The backwards RU is a UL mark.

B. This line shows that the motor is thermally protected, and then lists the Thermal Overload part number CET51ABM. The CSA logo is the Canadian Standards

C. MOTOR MODel number is used when replacing a motor, to get one with the same electrical construction. Serial Number? Not that useful; it just tells when it was made.

D. Line D shows the Volts 115/230, meaning this motor has reversible power, or can accept either. HP stands for Horsepower, in this case 1.0 hp.

E. AMPS is listed further down. Also on line E is PH for Phase, single phase in this case. CODE refers to the NEMA classification for motors.

F. RPM - revolutions per minute, 3450 for pool motor types. FR - Frame type, in this case a 56J. HZ stands for Hertz, 60 hz in the US and 50 Hz in other parts of the world.

G. Max Load Amps lists two numbers 15.0 / 7.5. The first number is max amps used when wired 115V, and the second number is amp draw for a 230V hookup. SF stands for Service Factor, and this tells if the motor is uprated, or max-rated. The SF number is multiplied by the HP number to find out total horsepower.

H. Insulation Class B is used for most spa and pool motors, AMB lists the maximum ambient temperature this motor should operate in, 50° Celsius, or 122° Fahrenheit. Time Rating of CONT means that this motor is made for Continuous Duty, or built to run all the time, if needed.

I: Motor TYPE is used to tell the type of motor used - CS for Capacitor Start, or UAK for Capacitor Start/Capacitor Run. The manufacturer Regal Beloit is listed and the country of construction, in this case China, is listed.


How to Select a New Pump Motor

If you are replacing a motor on your pool pump, it is critical to match it up exactly. Horsepower, Frame type, and Service Factor in particular. You can also use the model number to locate a replacement pool pump motor. If you have questions or need help with our pool motors and motor parts, take a picture of the motor nameplate and give our tech support line a call at 877-766-5287.


Thanks for Reading!
Mark Garcia