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Had a unusual one today....

KBeitz

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I came in from the shop to the house to wash my hands and the bathroom light refused to turn on. The light has two bulbs so I was thinking I had a different problem. Went to the basement and I found a tripped breaker. It's the same breaker that runs the water pump. I turned it back on and flames and sparks flew across the room. At first I had no idea where the sparks came from. I looked everything over and decided to try to reset the breaker again. More sparks... Still could not find where they came from... Spent 10 min. looking... Flipped the breaker for the third time and seen sparks coming from a switch I installed many years ago to shut off the water pump easy without crawling back in the water pump corner. Close inspection I found a little hole in the switch cover so I removed it. The hole continued into the switch. I've done electrical work all my life and never seen anything like this. The funny thing about it the motor to the water pump was not even running. The pressure was up and the pump pressure switch was off. Something happened inside the switch and burned the hole all the way through two pieces of metal. I had a box of old new papers right under the switch that I used in the winter to start my wood fires. Guess the man up stairs was looking out for me today... After I show this switch to a few people I think I will take it apart to see what happen.
 

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Latinrascalrg1

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Now that's a new one! It looks like someone drilled a hole intentionally! Im interested in what you find when you open it up!
 

kb58

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Probably a bunch of burnt and melted evidence.
 

brino

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Wow!
Is the switch rated for the current requirements of the pump motor?
-brino
 

Flyinfool

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I have never seen an install where the pump circuit powered anything but the pump.

I to will be curious as to what the failure mode is.
 

Superburban

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Is there a name on the switch? I would be interested in seeing what they have to say. Also, would this be something that should be reported to UL, or CPSC.

The few switches I have taken apart, I do not recall amything inside. The screw for the wire is in that area, but I cannot picture it arcing through both metals. In my mind, it would make a funnel or ball shaped hole, arcing to the nearest ground.
 

FOMOGO

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I have never seen an install where the pump circuit powered anything but the pump.





Pump should be on a dedicated circuit. At least here in CO, well pump power comes off the meter (before the main panel) to a separate weather proof, fused switch box on the exterior of the house generally next to your meter. Might want to look into some changes in your setup. Glad nothing bad happened. Mike
 

KBeitz

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I will post more pictures when I open the switch. I did the wiring and I was also surprised that the bath light was on the same line. I did the wiring about 40 years ago. I also thought the switch might have been a little light for the pump motor. but the funny thing was that it shorted out when the pump was off with the pressure switch but maybe the bath light was turned on.
 

ConValSam

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Sounds to me like a spontaneous EDM machine grew inside that switch. All you need to do is figure out how to harness it!
 

RJSakowski

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The hole appears to be directly over one of the switch contacts. If, for some reason there was an electrical arc inside the switch that burned through the Balelite and pierced the metal on the switch, it shouldn't have gone any further. The switch should have been grounded to the box by virtue of its mounting screws and the arc would have gone to ground. I can't see how it would continue to make a hole in the cover plate.

A more likely scenario is that a hole was drilled in the cover plate and the switch providing a path to ground and possibly damaging the electrical circuit within the switch. I have seen something similar with a lightning strike where lightning came down a television antenna lead and blew a half dollar sized hole in a breaker box. There was an associated fire that totaled the business though.

You didn't say what type of pump you had. If it is a deep well submersible, they are an excellent earth ground and attractive path for a lightning strike. I would agree with Flyinfool. A pump should have a dedicated circuit.
 

hman

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Sounds to me like a spontaneous EDM machine grew inside that switch. All you need to do is figure out how to harness it!
... either that, or you've invented a new kind of plasma cutter :)
 

Ulma Doctor

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one beautiful constant in electrical work, electricity is always seeking the easiest path to ground.

as i see it....
your switch failed through heat as seen by the ball like anomaly on the end of the contact bar as seen in the last photo.
carbon was created as the bakelite decomposed, making a normally insulated switch a conductor
the carbon created an easier path to ground through the metal front cover of the switch as well as the metal switch cover, which were undoubtedly in close proximity.
since there was some resistance, there was no direct short to ground.
it may have been rather slow decay not unlike electrolysis
but the end result was undeniable
 

RJSakowski

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one beautiful constant in electrical work, electricity is always seeking the easiest path to ground.

as i see it....
your switch failed through heat as seen by the ball like anomaly on the end of the contact bar as seen in the last photo.
carbon was created as the bakelite decomposed, making a normally insulated switch a conductor
the carbon created an easier path to ground through the metal front cover of the switch as well as the metal switch cover, which were undoubtedly in close proximity.
since there was some resistance, there was no direct short to ground.
it may have been rather slow decay not unlike electrolysis
but the end result was undeniable
What I don't understand is the hole in the cover plate. The cover plate is grounded through the switch body which should be connected to a ground wire. #Even if the ground wire were connected to the box, the path would be through the switch body. Why would a hole blow in the cover plate?
 

Superburban

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Thats interesting, I never knew bakelite degraded into carbon. You Google it, and there has been several studies on converting old bakelite into carbon.


Sounds to me like a spontaneous EDM machine grew inside that switch. All you need to do is figure out how to harness it!
Sounds like you are darn close.
 

RJSakowski

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Thats interesting, I never knew bakelite degraded into carbon. You Google it, and there has been several studies on converting old bakelite into carbon.
Actually it's quite common. Back when we still had distributors in cars, a little moisture or dirt would create a leakage path between terminals and the arc would create a permanent carbon path. Older printed circuit boards used phenolic board instead of the glass or polyester boards used now. A bad electrical connection would generate heat which would cause the phenolic resin to decompose creating a carbon short.
 

KBeitz

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The ground wire was grounded to the box. When I flipped the breaker it looked like a small torch shooting flames and sparks out of the little hole. Looking at the insides I cant see anywhere where anything touched to make a short. So I guess it had to be a carbon trail.
 
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