Well Pump Controller & Lightning

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Old 07-22-10, 02:31 PM
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Well Pump Controller & Lightning

My first post, so bear with me.
We have a well with a Franklin-Electric Subdrive 150 controller on the pump which is 3 phase. My problem is that it has been knocked out by lightning twice and at $2K a pop, is not insignificant. After the first hit, the original installer replaced the unit and installed a lightning assestor between the local circuit breaker and the pump controller box. It should be noted that with a main breaker box full of GFI and Arc-fault breakers, none of them tripped - only the one for the pump.

Lightning struck again! This time we had two TVs and two computers running at the time and again, the only casuality was the pump controller box - no breakers tripped other than the pump and the lightning arrestor installed after the first strike remained intact. The original installer replaced the unit and installed two more lightning arrestors all on the electrical input to the controller. I asked him if there shouldn't be an arrestor on the pump side of the controller because it seemed to me that that was the logical path for the surge to enter the controller since nothing else in the house was affected. He said no, that an arrestor couldn't be installed on a three phase pump.

Additional background - the house is grounded through the steel in the footer plus two 8' grounding rods at the house and 6 more 8' grounding rods between the house and where the supply comes off the pole (about 1400 feet away). The house appears to be well grounded. The well is 423 feet deep with 120 feet of steel casing at the top and is located about 50 feet from the house.

Anyone have any knowledge about this type of problem? It seems to me that I am getting a considerable charge from the line to the pump into the controller without damaging the pump!!?? How can I prevent another $2K hit? I seriously wonder about the effectiveness of the location of the current lightning arrestors.

Sorry to be so wordy - this thing is driving me nuts.
 
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Old 07-22-10, 03:12 PM
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I think you need to bring the well casing into your grounding electrode system by running a #4 solid copper wire from the metal well casing to the ground/neutral bus at the panel where the other electrodes connect (Ufer footings, ground rods).

I suspect your lightning problems are the result of an elevated ground potential at the house relative to the well. Essentially a 10' deep damp rod in the foundation vs. a 120' deep wet rod at the well produces a much different level of "ground". Lightning arrestors are worthless in this type of problem because the power conductors inside the home are not even involved. If the well ground and the house ground are not solidly bonded to each other, there is the chance for high currents to flow on the pump conductors between the house and well during a lighting strike.

BTW, this is only for incidental lightning strikes. A direct or nearly-direct lightning strike is almost impossible to mitigate without an engineered grounding system.

edit: Also, I assume the controller is mounted in the house and only the conductors for the pump go out to the well? Is there a subpanel or any other electric to the well? Or a structure like a wellhouse?
 

Last edited by ibpooks; 07-22-10 at 03:38 PM.
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Old 07-22-10, 11:00 PM
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I will follow with Ibpooks advise here and you say 3 phase well pump motor ?

This is not too common found in resdentail area but I know in Farm or super deepwell pump yeah I can see that point of view however some pump are called 3 wire single phase pump which it will have remote start and run capaitors and relay on the control box.

Some well pump controller do have single phase input and three phase output as well.

But if you have legit three phase supply to your place what voltage you are on ?? { on three phase side it will be 208 or 240 or 480 line to line but the 480 is pretty much restricted to commercal side }

Second thing the bonding to the well I have see too many peoples use undersized bonding or grounding conductors you will need either 16mm˛ or 25mm˛ { #6 or #4 AWG } from load centre to the pump well casing.

That will really reduce amout of damage to lighting strike.

Merci.
Marc
 
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Old 07-23-10, 07:05 AM
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I could easily see lightning surges coming in from the well. My home gets hit (not directly) every year but the surge always comes in on the phone line. after about 5 DSL modems, 4 routers, some NIC cards and a few phone systems I pretty much have it taken care of with surge protectors. Seams odd to me that you can't protect the load side of the controller but at $2k a pop, it must be more than just a standard pressure switch. Do some looking on Google. I did a search for "three phase surge protection" and got quite a few hits. Surly somebody makes something for this as I would think it would be a common problem on farms.

IMO - Having redundant protection on the line side is, well, redundant. seams to me that you are correct that the surge is from the well side, not the service side.
 
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Old 07-23-10, 10:22 AM
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Toyln.,

Yeah there are few three phase surge protection devices on market I know Intermatic do make them as well

Here one product I do sell from time to time

AG Indicator Series | Intermatic, Inc.

that one type and there are couple other verson on market as well.

Merci.
Marc
 
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Old 07-24-10, 04:07 PM
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Hey folks!
Thanks tor the great input!

To answer some questions:
It is single phase 220V power into the control box which converts it to 3 phase for the pump. The installer said that out of nearly 300 of these systems he has installed over the years, he has seen only 3 fail this way (one of the three is mine!). The control box is mounted in the basement and the conductors go out to the well from there - no other structures or panels. The system is fed by 40A double breaker from the main panel to a 30A breaker in a sub panel before feeding the control box. The lightning arrestors are installed (1) in the main panel on the 40A breaker, (2) on the input side of the 30A breaker and (3) on the output side of the 30A breaker.

I can understand the difference in ground potential. Installing ~150 feet of #4 copper to connect the two sounds like cheap insurance compared to a $2K controller. Local code does not allow a "spliced" ground - would this be a problem?

I had contacted Franklin Electric, the manufacturer of the controller and the pump and got ZERO response. You folks are terrific!
 
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