Well Pump Struck by Lightning

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bcm

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Atlanta, Georgia
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Engineer
Greetings!

My boss asked me a question I am not exactly qualified to answer as I have nearly 0 pump experience.

He has a well pump pulling water from a 200' deep well that he uses for irrigation purposes at his home. The pump has a disconnect switch and surge protection at the house panel and also is grounded to a rod; however, the pump has been destroyed now by lightning striking somewhere nearby. He is thinking that the current is coming through the ground and hitting the pump and following the piping down to the water. The pump is in an area with trees nearby but it is over 100' from the home.

The disconnect and surge suppression show no signs that there has been a lightning strike, but he's had to replaced the pump twice in 6 months now.

Does anybody have an idea how to stop the lightning from destroying the pump? A friend suggested placing a length of pvc in the pipeline to break the "grounding system" the copper tubing creates by going down so far. Would this work? Any other ideas?

Thanks so much!

Bobbi
 
Why are you so certain that lighting is the culprit?
Do the pump motors show signs of lightning damage, or do they just stop working?

steve
 
Well Pump Struck by Lightning

Steve,

I'm not "so certain". I can only go on what my boss has told me about the situation.

I have not seen the ruined pumps or the property. Since both pumps stopped functioning after storms, he has concluded that it's lightning that caused the damage.

Bobbi
 
bcm said:
.
Does anybody have an idea how to stop the lightning from destroying the pump? A friend suggested placing a length of pvc in the pipeline to break the "grounding system" the copper tubing creates by going down so far. Would this work? Any other ideas?
Click to expand...

The copper tubing probably only goes to the well head, and then the casing which is usually sunk down to bedrock. I doubt the copper tubing is the issue.

And I doubt that the lightning is getting to the motor through the grounding system. I would be more inclined to suspect the the surge suppressor has failed, or maybe installed improperly, or might be the wrong kind, if indeed you are getting lighting problems. But, one might be inclined to think other things would have failed at the same time if lightning was the culprit. Motors tend to be fairly robust.
 
In my somewhat limited understanding of TVSS's, I have come to the conclusion that most are improperly installed, based upon the manufactures literature, which electricians NEVER READ.

Keep the conductor length short as possible.
Bind the conductors from point of connection to the TVSS.
Keep the conductors as straight as possible.
Read the instruction manual.
 
You might also look into whether this particular pump is rated for the duty cycle it's being put to, whether or not the bladder is shot in the bladder tank (short cycling the pump to death), and calculate what the voltage drop is by the time the cable gets to the pump. These three factors are the main killers of well pumps in my experience. I have already pulled pumps that were perfectly fine, but the cable had failed at some point between hither and tither and the pump got the blame in the mean time.
 
bcm,

I can see why the lightning would be atracted to this Grounding Electrode,

my guess as why the motors are getting sizzeled is the EGC to the motor

is not connected or does not exist with the branch circuit conductors.

I see that these motors are sold with either 2 wire or 3 wire cords for the

same voltage, if the original was a 2 wire and the replacement is a 3 wire

then the lightning has a chance to jump to it. JMO.
 
benaround said:
bcm,



I see that these motors are sold with either 2 wire or 3 wire cords for the

same voltage, if the original was a 2 wire and the replacement is a 3 wire

then the lightning has a chance to jump to it. JMO.
Click to expand...

A two wire pump or a three wire pump still has a ground.... or were you saying the extra conductor could be a problem? And most pumps have lightning arrestors built into them, but that is no guarantee either...
 
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mdshunk said:
You might also look into whether this particular pump is rated for the duty cycle it's being put to, whether or not the bladder is shot in the bladder tank (short cycling the pump to death), and calculate what the voltage drop is by the time the cable gets to the pump. These three factors are the main killers of well pumps in my experience. I have already pulled pumps that were perfectly fine, but the cable had failed at some point between hither and tither and the pump got the blame in the mean time.
Click to expand...

I agree with Marc.

As far as the lightning goes, it is very destructive and will usually leave more obvious damage than just a bad pump. The last few lightning strike jobs I went to, the items affected tripped or disintegrated the OCPD and had visual signs of mother natures wrath
 
in your original explanation you mentioned "the pump is connected to a ground rod" it is very important that the ground rod that grounds the pump is the same ground rod that grounds the power source that feeds the pump??

i agree with the other posts that a surge protector be properly installed on this circuit--the circuit that feeds the pump.

also consider the amount of time the pump is operating increases it's chances to be affected by a surge or flash. there is a mechanical "gizmo" that has been on the market for about four years--it looks like a check valve--but isn't!!! electrician's veiwpoint!!! it installs on the well head before anything.. it costs about $18.00 and will save it's costs in less than two years. most major pump manufacturers will double their original warantee on the pump if this item is installed. the "gizmo" prevents short cycling of the pump from pressure drops when the start pressure is close to starting the pump oooorrrrrrr ---- it reduces the number of pump starts and therefore reduces the amount of run time. i have one for my water system -- haven't installed it yet ---- waiting for a stike --- i guess!!! you know how that goes!!!!
 
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