I posted this on another forum under a debate on what pump to use. Most suggest the blue Harbor Fright pumps and many warn about them blowing or catching on fire…
Here is a little Vid I made that shows the voltage and the blown cap.
I thought I would share this with you guys. One of my blue harbor freight pumps went up in smoke last weekend. We use this one for water only to water the garden. The run cap popped and puked its guts out inside the plastic power box on top and made some smoke. Now that the run cap was out of the loop the windings on the inside are introduced to the straight line voltage and they started to burn/ melt. Good thing I was standing there when it popped and pulled the plug before the windings could melt and short the motor.
So here is WHY they blow. My dad’s house line voltage is 130 usually. We have even seen up to 136 at times. Well the run cap is only rated at 240 v. Now if you have 120 line volts then the voltage across the cap is 240 which is JUST hardly with in the caps limit.
I don’t know exactly why the windings and the cap measure double, but they do. I watched my dad measure them with the meter. He was explaining it to me but I can not remember right now as to why. My dad use to design motors and systems using motors (and also build electric motors) so he is some kind of genius at this stuff I guess.
Well my dad’s house is always 130+ volts and that puts the cap at 260 volts. Most caps can handle 5 to 10% over and be ok for a little time but not forever. If the cap pops and the windings melt, you will see lots of smoke (varnish on the windings melting along with the bamboo spacers in the middle of the windings) and you could see flames. Mostly smoke and stink.
So the fix? A cap rated at 370 or 480 VAC. Granger has them for 8.96 or allied has similar for 6 bucks. The cap that comes with the motor is a 16 uf (micro faried) 240vac. I bought a few 15 uf 370 volt caps and will be replacing them on all my pumps (2 Biod Pumps and 3 water pumps) Remember make sure that you get AC rated caps NOT DC. I did not express this the first time around (I knew it and assumed that everyone else would know...) but thanks to rydogg on another forum for pointing that out to everyone.
O the down side is that they need to be remote mounted since they will not fit in the box on the top of the motor. Ill try to get some pics soon for you guys.
I installed the grainger one last night and all was good. Waiting on the allied ones to show up and see if they are ok.
Motors > Motor Supplies > Capacitors > Run Capacitor,15 MFD,370 VAC : Grainger Industrial Supply
Cornell-Dubilier - 37FD3715-F - Allied Electronics
Here is the popped cap