# Water well start capacitor burns s **URL:** \ **Category:** Factual Questions\ **Created:** [June 13, 2015, 3:59am UTC](https://boards.straightdope.com/t/water-well-start-capacitor-burns-s/722411 "2015-06-13T03:59:09Z")\ **Posts on this page:** 16\ **Page:** 1
**Author:** ![MPrice0311](https://avatars.discourse-cdn.com/v4/letter/m/ccd318/32.png) [@MPrice0311](https://boards.straightdope.com/u/MPrice0311)\ **Post date:** [June 13, 2015, 3:59am UTC](https://boards.straightdope.com/t/water-well-start-capacitor-burns-s/722411/1 "2015-06-13T03:59:09Z")
I have a water well but no idea how long it has been in. When I moved into the house, I looked at the control box. The capacitor looked as if it was melted from the inside. I replaced the entire box but as soon as I turned the power on, the capacitor began leaking fluid and smoke. I replace the control box with the same amps/volts as the one that was on it. Any idea what would cause this? Hoping to not have to remove the pump. ---
**Author:** ![Boogly](https://avatars.discourse-cdn.com/v4/letter/b/f4b2a3/32.png) [@Boogly](https://boards.straightdope.com/u/Boogly)\ **Post date:** [June 13, 2015, 4:09am UTC](https://boards.straightdope.com/t/water-well-start-capacitor-burns-s/722411/2 "2015-06-13T04:09:42Z")
Did you check the power lines to/from the pump for fraying? I had this happen last year and it was a frayed power line, but we didn’t find it until after pulling the pump. ---
**Author:** ![MPrice0311](https://avatars.discourse-cdn.com/v4/letter/m/ccd318/32.png) [@MPrice0311](https://boards.straightdope.com/u/MPrice0311)\ **Post date:** [June 13, 2015, 4:13am UTC](https://boards.straightdope.com/t/water-well-start-capacitor-burns-s/722411/3 "2015-06-13T04:13:07Z")
> [@Boogly](#): > > Did you check the power lines to/from the pump for fraying? > > I had this happen last year and it was a frayed power line, but we didn’t find it until after pulling the pump. I did not see any fraying, but am hoping not to pull the pump. ---
**Author:** ![beowulff](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/beowulff/32/542_2.png) [@beowulff](https://boards.straightdope.com/u/beowulff)\ **Post date:** [June 13, 2015, 4:56am UTC](https://boards.straightdope.com/t/water-well-start-capacitor-burns-s/722411/4 "2015-06-13T04:56:47Z")
Sounds like a shorted winding in the motor. Or, the centrifugal switch is broken and not turning off. ---
**Author:** ![boytyperanma](https://avatars.discourse-cdn.com/v4/letter/b/4491bb/32.png) [@boytyperanma](https://boards.straightdope.com/u/boytyperanma)\ **Post date:** [June 13, 2015, 5:08am UTC](https://boards.straightdope.com/t/water-well-start-capacitor-burns-s/722411/5 "2015-06-13T05:08:46Z")
> [@MPrice0311](#): > > I have a water well but no idea how long it has been in. When I moved into the house, I looked at the control box. The capacitor looked as if it was melted from the inside. I replaced the entire box but as soon as I turned the power on, the capacitor began leaking fluid and smoke. I replace the control box with the same amps/volts as the one that was on it. Any idea what would cause this? Hoping to not have to remove the pump. I’d be a bit concerned about the quality of the control box. Even if the pump is bad a new capacitor shouldn’t fry like that. You need to do an electrical check. The red yellow and black wires go to the pump. Test each of those to ground with an Ohm meter. I expect each will show a dead short. Take a picture of the old control box, and the area of the pressure tank. I can probably tell you a bit about the pump. ---
**Author:** ![Leaffan](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/leaffan/32/299_2.png) [@Leaffan](https://boards.straightdope.com/u/Leaffan)\ **Post date:** [June 13, 2015, 5:22am UTC](https://boards.straightdope.com/t/water-well-start-capacitor-burns-s/722411/6 "2015-06-13T05:22:48Z")
One thing’s for certain, the starting capacitor is pooched and will need to be replaced. It may be cheaper just to buy the whole box again. I replaced my control box years ago because of a dead capacitor with no issues. Something else is the cause of your concern and you probably need an expert to troubleshoot that. ---
**Author:** ![boytyperanma](https://avatars.discourse-cdn.com/v4/letter/b/4491bb/32.png) [@boytyperanma](https://boards.straightdope.com/u/boytyperanma)\ **Post date:** [June 13, 2015, 5:37am UTC](https://boards.straightdope.com/t/water-well-start-capacitor-burns-s/722411/7 "2015-06-13T05:37:32Z")
> [@Leaffan](#): > > One thing’s for certain, the starting capacitor is pooched and will need to be replaced. It may be cheaper just to buy the whole box again. It’s better to just to replace the control box, the issue could also be the relay is bad, which fries the capacitor. It also works vice versa. We used to carry the components, test, replace and rebuild control boxes as needed. Now with labor rates what they are it’s cheaper for the customer to swap out the box. It’s 2 minutes to swap a control box cover. It’s a half hour to rebuild them. ---
**Author:** ![Leaffan](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/leaffan/32/299_2.png) [@Leaffan](https://boards.straightdope.com/u/Leaffan)\ **Post date:** [June 13, 2015, 5:52am UTC](https://boards.straightdope.com/t/water-well-start-capacitor-burns-s/722411/8 "2015-06-13T05:52:11Z")
> [@boytyperanma](#): > > …It’s 2 minutes to swap a control box cover… Ha. That’s exactly what I replaced, come to think of it. The electronics are in the cover and all I did was plug the new cover in and tighten the screw. ---
**Author:** ![MPrice0311](https://avatars.discourse-cdn.com/v4/letter/m/ccd318/32.png) [@MPrice0311](https://boards.straightdope.com/u/MPrice0311)\ **Post date:** [June 13, 2015, 6:31am UTC](https://boards.straightdope.com/t/water-well-start-capacitor-burns-s/722411/9 "2015-06-13T06:31:14Z")
> [@boytyperanma](#): > > I’d be a bit concerned about the quality of the control box. Even if the pump is bad a new capacitor shouldn’t fry like that. > > You need to do an electrical check. The red yellow and black wires go to the pump. Test each of those to ground with an Ohm meter. I expect each will show a dead short. > > Take a picture of the old control box, and the area of the pressure tank. I can probably tell you a bit about the pump. I have a multimeter but not really sure how to use it. I set it on 2000 k ohms and it reads “I” for the yellow wire when placed on the ground wire. But reads “230” for the red and blk. ---
**Author:** ![boytyperanma](https://avatars.discourse-cdn.com/v4/letter/b/4491bb/32.png) [@boytyperanma](https://boards.straightdope.com/u/boytyperanma)\ **Post date:** [June 13, 2015, 9:49am UTC](https://boards.straightdope.com/t/water-well-start-capacitor-burns-s/722411/10 "2015-06-13T09:49:00Z")
> [@MPrice0311](#): > > I have a multimeter but not really sure how to use it. I set it on 2000 k ohms and it reads “I” for the yellow wire when placed on the ground wire. But reads “230” for the red and blk. ‘1’ means infinite. You’d need to make sure you are testing the wires that go to the pump. The incoming power can also be red and black. most common with incoming is black and white. I need pictures. Ohm readings red to black, red to yellow, yellow to black? ---
**Author:** ![Leaffan](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/leaffan/32/299_2.png) [@Leaffan](https://boards.straightdope.com/u/Leaffan)\ **Post date:** [June 13, 2015, 10:47am UTC](https://boards.straightdope.com/t/water-well-start-capacitor-burns-s/722411/11 "2015-06-13T10:47:37Z")
> [@MPrice0311](#): > > I have a multimeter but not really sure how to use it. … You need to call someone. You can’t fix this yourself. ---
**Author:** ![md2000](https://avatars.discourse-cdn.com/v4/letter/m/73ab20/32.png) [@md2000](https://boards.straightdope.com/u/md2000)\ **Post date:** [June 13, 2015, 1:02pm UTC](https://boards.straightdope.com/t/water-well-start-capacitor-burns-s/722411/12 "2015-06-13T13:02:51Z")
Back about a decade ago, a large number of computers were made with faulty capacitors - after a few years of use the capacitors started bulging, then failing. The fluid inside was incorrectly formulated, causing the capacitor to fail. I have not heard of this being a problem with large electrolytic capacitors for power uses; generally the problem I’ve seen relates to pencil-tip-eraser-sized capacitors on computer motherboards. But it’s possible this is why the capacitor failed, and it’s the source, not the result, of the problems. > **[Capacitor plague](https://en.wikipedia.org/wiki/Capacitor_plague)** > > The capacitor plague was a problem related to a higher-than-expected failure rate of non-solid aluminium electrolytic capacitors between 1999 and 2007, especially those from some Taiwanese manufacturers, due to faulty electrolyte composition that caused corrosion accompanied by gas generation; this often resulted in rupturing of the case of the capacitor from the build-up of pressure. > High failure rates occurred in many well-known brands of electronics, and were particularly evident in motherb... > [@](#): > > Industrial espionage implicated[edit] > > A major cause of the plague of faulty capacitors was industrial espionage in connection with the theft of an electrolyte formula. A materials scientist working for Rubycon in Japan left the company with the secret electrolyte formula for the ZA and ZL series of Rubycon and began working for a Chinese company. The scientist then developed a copy of this water-based electrolyte. After that some staff members who defected from the company copied an incomplete version of the formula, and began to undersell the pricing of the Japanese manufacturers with this electrolyte to many of the aluminum electrolytic manufacturers in Taiwan.[1][42] The subsequent electrolyte produced lacked important proprietary ingredients which were essential to the long-term stability of the capacitors,[4][6] and was unstable when packaged in a finished aluminum capacitor. The bad formulation of electrolyte allowed the unimpeded formation of hydroxide and produced hydrogen gas.[33] > > There are no known public court proceedings related to alleged theft of electrolyte formulas. However, one independent laboratory analysis of defective capacitors has shown that many of the premature failures do appear to be associated with high water content and missing inhibitors in the electrolyte, as described below ---
**Author:** ![boytyperanma](https://avatars.discourse-cdn.com/v4/letter/b/4491bb/32.png) [@boytyperanma](https://boards.straightdope.com/u/boytyperanma)\ **Post date:** [June 13, 2015, 1:51pm UTC](https://boards.straightdope.com/t/water-well-start-capacitor-burns-s/722411/13 "2015-06-13T13:51:03Z")
> [@Leaffan](#): > > You need to call someone. You can’t fix this yourself. I do have to admit defeat and agree with you. Problem is most likely the pump. There is a chance if he/she rewired the control box wrong it created the issue, in which case they should have called a professional to begin with. ---
**Author:** ![Isilder](https://avatars.discourse-cdn.com/v4/letter/i/cc9497/32.png) [@Isilder](https://boards.straightdope.com/u/Isilder)\ **Post date:** [June 13, 2015, 2:00pm UTC](https://boards.straightdope.com/t/water-well-start-capacitor-burns-s/722411/14 "2015-06-13T14:00:08Z")
Could be as cleaning and lubing a centrifugally operated switch… See [Another motor start capacitor craps the bed](http://forum.woodenboat.com/showthread.php?149003-Another-motor-start-capacitor-craps-the-bed) ---
**Author:** ![Crafter\_Man](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/crafter_man/32/458_2.png) [@Crafter\_Man](https://boards.straightdope.com/u/Crafter_Man)\ **Post date:** [June 13, 2015, 5:20pm UTC](https://boards.straightdope.com/t/water-well-start-capacitor-burns-s/722411/15 "2015-06-13T17:20:55Z")
It’s not difficult to check a three-wire submersible pump using a ohmmeter. The motor in the pump has two windings: a start winding (red & yellow) and a run winding (black & yellow). The metal case of the pump is connected to the green wire, and we call this “ground.” After cutting power to the control box, disconnect the four wires (red, black, yellow, and green) from the control box. Measure the insulation resistance (IR) between the windings and ground using a ohmmeter (or better yet, an IR meter such as the ones made by Megger): - Measure the resistance between the red and green wires. It should ideally be infinite. A reading above 2 MΩ is generally considered to be “good.” - Measure the resistance between the black and green wires. It should ideally be infinite. A reading above 2 MΩ is generally considered to be “good.” - Measure the resistance between the yellow and green wires. It should ideally be infinite. A reading above 2 MΩ is generally considered to be “good.” (Note that if there are no discontinuities in any of the windings, then only one of the three above measurements needs to be taken. But it’s simple to do all three, so you may as well do all three.) Next measure the resistance of the start and run windings using an ohmmeter. The nominal values for each are found in the installation manual. For most 3-wire pumps, the resistance of the start winding is somewhere between 10 Ω and 20 Ω, and the resistance of the run winding is somewhere between 3 Ω and 6 Ω. The resistance values will also include the resistance of the wiring, so don’t be too hung up on the precise value: - Measure the resistance between the red and yellow wires. For most pumps it’s between 10 Ω and 20 Ω. A very low value (e.g. 1 Ω) is indicative of a shorted start winding. A very high value (\>1 MΩ) is indicative of an open start winding. - Measure the resistance between the black and yellow wires. For most pumps it’s between 3 Ω and 6 Ω. A very low value (e.g. 1 Ω) is indicative of a shorted run winding. A very high value (\>1 MΩ) is indicative of an open run winding. - Measure the resistance between the red and black wires. (You are measuring both windings in series here.) For most pumps it’s between 13 Ω and 26 Ω. ---
**Author:** ![user\_hostile](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/user_hostile/32/474_2.png) [@user\_hostile](https://boards.straightdope.com/u/user_hostile)\ **Post date:** [June 13, 2015, 6:06pm UTC](https://boards.straightdope.com/t/water-well-start-capacitor-burns-s/722411/16 "2015-06-13T18:06:46Z")
> [@md2000](#): > > Back about a decade ago, a large number of computers were made with faulty capacitors - after a few years of use the capacitors started bulging, then failing. The fluid inside was incorrectly formulated, causing the capacitor to fail. > > I have not heard of this being a problem with large electrolytic capacitors for power uses; generally the problem I’ve seen relates to pencil-tip-eraser-sized capacitors on computer motherboards. But it’s possible this is why the capacitor failed, and it’s the source, not the result, of the problems. > > [Capacitor plague - Wikipedia](https://en.wikipedia.org/wiki/Capacitor_plague) Hah! That explains the graphics card failure from eight years ago–when it died, most of the electrolytic caps looked liked they vomited foam.