Motor 56c Keyed Full 1.5 Hp (b123)



Part # 5204X

By Century Motors

  4.34 Average  



Part # 5204X

Manufacturer Code B123

Alternate Part #'s 1096, 1104375401, 113686, 13592, 141930, 142459, 142775, 158127, 158961, 159985, 164124, 164128, 164300, 164430, 164440, 164444, 177471, 190000, 1D173, 1K043, 35-6403, 5KCR49UN2087X, 7-164300-23, 7-164300-24, 716430024, 8-164300-23, A600FH, A600FHL, B706, B795, B796, C1096, CD15FL1, CK115, EB123, MGT605094, P704, S88-174, SK1152, 35-126-1406

Product Description


Motor Dimensions Motor Dimensions
Motor Image Motor Image

Product Specifications

Motor Name:
1.5 HP B123 Replacement Pool Motor
1.5 HP
3450 RPM
230/115 V
9.2/18.4 amp
Service Factor:
Total HP:
1.95 HP
Stock #:
Overload Protector:
Dimension Letter:
13.19 in.
Commonly Used On:
Sta-Rite, Hayward, American Products, Hydra Bath, Pac Fab, Jacuzzi, Doughboy

?     Asked on 10/14/2021by Roger Q Tarrant

I have a failed Magnetek Century Centurion B123, Part B 164300-23, FR N56C, Type CX, pump. Is what you have the correct replacement? I have heard that brushless permanent magnet motors have higher efficiency and reliability than the old coil motors. Is there a possibility for me to get one of the newer design?

A  Answered on 10/15/2021 by InyoPools Product Specialist Craig C.

Hello Roger.  The correct replacement for your Magnetek Century Centurion Motor model B123 is the Century Motors model B123.  Motor 56c Keyed Full 1.5 Hp (b123)   Brushless permanent magnet motors (variable speed) are more energy-efficient than conventional copper-wound motors.  They are totally enclosed which helps prevent moisture from entering the motor, lending them to a longer life span.  According to Regal/Beloit (manufacturer of Century/A. O. Smith copper wound and variable speed motors), there is currently no brushless permanent magnet motor available as a direct replacement for the Century Motors B123 motor.

?     Asked on 5/8/2019by Inyo Visitor

My current motor is a magnetek N56c 1.5 hp motor. Part 8 164300-23 type cx. This is the correct replacement right? Thanks


A  Answered on 5/8/2019 by InyoPools Product Specialist Lennox H.

Hi. Yes, this B123 is the correct replacement for your motor. 

?     Asked on 5/7/2019by Omar

I have an advantage manufacturing motor for residential use 1.5 up, 3500 rpm 60 hz, 56 fr, 115/230 volt would this work

A  Answered on 5/10/2019 by InyoPools Product Specialist Lennox H.

Hi, Omar. Unfortunately, I unable to confirm using the info provided. Please provide the motor # or the SF #.

?     Asked on 3/26/2018by David D

I have a MagneTeK Century Electric Pool and Spa Duty; 1081 pool pump duty mount horizontal with vent holes down; Thermally protected KA; HP 1.5; SF 1.3; Volts 230/115 Amps; SFA 18.4/9.2; Frame N56C; Time CONT; RPM 3450; CAT B123; Part 8-461300-20; AMB 50 degree C; Insul class B; Form K JM; Hz 60; Encl DP; PH 1; Code H; Serial BG8-113 that works but I would like to replace with a variable speed motor to save electricity. Can you point me to a replacement? Thank you.

A  Answered on 3/27/2018 by InyoPools Product Specialist Lennox H.

Hi, David D. Unfortunately, there is not a replacement variable speed motor that will replace this B123 motor. 

?     Asked on 1/19/2018by keith

have pump motor out it is ao smith cat B123 part 7-164300-24

A  Answered on 1/22/2018 by InyoPools Product Specialist Lennox H.

Hi, Keith. This B123 motor is the correct replacement. 

?     Asked on 6/28/2017by Inyo Visitor

Looking to replace a do I know if keyed or not without disconnecting? I have a magnatek 1.5 hp. From Data label on motor: (part 10-164300-23) SF 1.3 / 3450 RPM/ Frame N56C/Serial B84-24/Type CX/CAT B123 Thanks

A  Answered on 6/28/2017 by InyoPools Product Specialist Stacey M.

Hello, The motor that replaces is a Motor 56c Keyed Full 1.5 Hp (b123)

?     Asked on 4/16/2017by Inyo Visitor

i have a 1993 centurion switchless motor HP1.2, SF1.60, fr K56C, rpm 3450, time continuouis motor that will not spin. i hear the the power getting to it but it will not spin. im looking form a pump to replace this one for a pond/fountain. any suggestions please i need asap

A  Answered on 4/19/2017 by InyoPools Product Specialist Scott W.

If you have the pump model and the motor part or model number I can help you with the motor and shaft seal replacement. If you are wanting the complete pump I just need the pump model. If you do not have this information please attach a picture so I can identify it for you.

?     Asked on 4/13/2017by DAVID T ENSIGN

I have a PAC FAB Hydropump with a 1hp Goulds motor part # 8-152540-21. I need an external capacitor but the number in unreadable. do you have one or could you provide me a part #? Also, will the 1.5 Hp (b123) replace my motor.

A  Answered on 4/13/2017 by InyoPools Product Specialist Scott W.

The capacitor for that motor is part number 5270-14, and yes, your B123 will replace your current motor but you would also have to upgrade your impeller as well, part number 5000-3049.

?     Asked on 8/14/2016by Craig

Will this work for replacing my MagneTek Centurion motor B750 8-164718-02 1.5 HP FR=N56C ? It is attached to Purex equipment.

A  Answered on 8/20/2016 by InyoPools Product Specialist Lennox H.

Hi Craig, Yes. This motor can be used as a replacement for p/n 8-164718-02.

?     Asked on 6/10/2016by John

Will this motor fit my older Anthony bronze pool pump. If yes, what is your return policy if it doesn't fit in the space available? Thanks

A  Answered on 6/19/2016 by InyoPools Product Specialist Lennox H.

Hi John, If you have the Anthony ASAC Pump then this motor can be used with that pump. However, if you can provide the motor's part, cat or mod # I can confirm which motor you need as a replacement.

?     Asked on 2/28/2016by Inyo Visitor

how do i get the inpeller off my 1.5 hp pentair pump

A  Answered on 2/28/2016 by InyoPools Product Specialist Patrick P.

We have a great Video on How to Replace a Pool Pump Impeller which goes into full detail on how to remove your impeller.

?     Asked on 1/11/2012by Guest

What is Service Factor?

A  Answered on 1/11/2012 by InyoPools Product Specialist Patrick P.

Service Factor(SF) is a multiplier that when multiplied by the horsepower of the motor indicates the total permissible horsepower loading that may be carried when the motor is operating at rated voltage and frequency. The most important thing to remember when replacing a motor is that the replacement motor's horsepower times its service factor must be equal to or greater than the original motor's horsepower times its service factor. The Service Factor rating can be found on the motor label. See Step 4 of our How to Read a Pool Motor Label guide.


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