ECN Electrical Forum - Discussion Forums for Electricians, Inspectors and Related Professionals
ECN Shout Chat
Shout Box
Recent Posts
Recall notice: Southwire wi-fi wall switches
by sparkyinak. 03/15/18 06:03 PM
Goodman Manufacturing Recalls Modular Blowers
by Admin. 03/13/18 10:40 PM
MAAX Spas Recalls Hot Tubs and Swim Spas
by Admin. 03/13/18 10:29 PM
New in the Gallery:
Housebilding DIY wiring
SE cable question
Who's Online Now
0 registered members (), 9 guests, and 8 spiders.
Key: Admin, Global Mod, Mod
Previous Thread
Next Thread
Print Thread
Rate Thread
Run Capacitor Value #69946
09/25/06 04:37 PM
09/25/06 04:37 PM
wendel  Offline OP
Joined: Aug 2004
Posts: 55
I was servicing a generic pool pump motor. It's a Century Electric (Magnetek) 1 hp, 3450 rpm, 230/115 volt, 56J frame, part #B828.

I noticed the capacitor was badly rusting. I couldn't clearly read the capacitor's label. It appears to be 20 mfd but I need to verify that value. Possiby some of you have serviced pool motors. Does 20 mfd seem to be a reasonable value for the above described motor? I've tried to locate data on it but without success. Any help greatly appreciated... I may need a new capacitor soon.

Work Gear for Electricians and the Trades
Re: Run Capacitor Value #69947
09/25/06 09:21 PM
09/25/06 09:21 PM
Crowbar  Offline
Joined: Jan 2003
Posts: 33
Pittsburgh, PA,USA
Century has been bought out by A.O. Smith, 20 mfd sounds reasonable to me, here is link that may provide more information.

Re: Run Capacitor Value #69948
09/26/06 04:53 AM
09/26/06 04:53 AM
RODALCO  Offline
Joined: Dec 2005
Posts: 856
Titirangi, Akld, New Zealand
20 µF is a reasonable value for a 1 HP motor.
These pump motors start usually under lightly loaded conditions.

Normally 55 µF per kW for medium loaded motors I go by so the 20 µF should work fine.

The product of rotation, excitation and flux produces electricty.
Re: Run Capacitor Value #69949
09/27/06 05:02 AM
09/27/06 05:02 AM
pauluk  Offline
Joined: Aug 2001
Posts: 7,520
Norfolk, England
From Alan Belson:

I'd go for about 20uF per horsepower, if you can't read the OE label, but I'm told by my friendly Scot neighbor "dinna gae any higher".

And I second the comments about frequent starts - Pic, "balloon capacitor", is what happened when I pushed a 3hp motor too hard.
BTW the motor still just about started, [after a struggle], which reason led to the discovery of the problem.

Rod, 55uF per kW?

[Linked Image]

[This message has been edited by pauluk (edited 09-27-2006).]


2017 Master Electrician Exam Preparation Combos
2017 NEC Electrician
Exam Prep Combos:
Master / Journeyman


Member Spotlight
L.I. New York
Posts: 95
Joined: August 2003
Show All Member Profiles 
Top Posters(30 Days)
Trumpy 5
Admin 5
Popular Topics(Views)
244,407 Are you busy
181,523 Re: Forum
171,572 Need opinion
Powered by UBB.threads™ PHP Forum Software 7.6.1
(Release build 20180101)
Page Time: 0.012s Queries: 14 (0.003s) Memory: 0.9593 MB (Peak: 1.0902 MB) Zlib enabled. Server Time: 2018-03-19 06:44:30 UTC