This article was posted 08/30/2006 and is most likely outdated.

Protecting Submergible Pump from Lightning

Topic - Lightning and Surge Protection
Subject - Protecting Submergible Pump from Lightning

August 31, 2006  

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Protecting Submergible Pump from Lightning


Question from newsletter member:




I have a 150’ ground water well with a steel encasement, the well has a submergible pump located at the bottom of the well with a ground wire going to the pump.


The steel pipe/encasement for the submergible pump is not grounded to the electrical system. The pump seems to burn out and trip the breaker for no apparent reason.


I am thinking of grounding the steel pipe/encasement to the submergible pump ground wire, due to lightning traveling down the ground wire 150’ to the pump housing. However, I am not sure if that will only make the problem worse, due to more surface contact with the earth. This site is located in the Florida Everglades with lots of lightning, any recommendations?


Chuck Maxfield

Apex Electric


Mike asked his friend John West with Power & Systems Innovations, Inc. to respond:


Most wells are installed without consideration of the impact the earthing effect of the casing and what can happen with nearby lightning events. The energy of lightning is not predictable, but most often it follows any and all paths that present a lower potential. Lightning traveling in the ground will see the well casing the same as lightning in the air would see a 150’ tower. It will couple with the casing and follow the conductors of the pump back to the “lower” potential. That most often will burn the pump out. There are two things you can do; bond the casing to the service ground and install a good performance TVSS (surge protector).


If I understand the installation (if I don’t please correct me) the well casing is not bonded or connected in any manner to your electrical service ground bond. There is no doubt the well casing is the best ground you have available. As you have stated it is probable the pump damage has resulted from lightning.


Part 1: I recommend you bond the well casing to your service entrance grounding. The distance between the well and your electrical service would determine the size of the conductor. Our firm uses 4/0 bare stranded conductor in most cases. In corrosive or salt soil areas we use tinned wire. The larger the size of the bonding conductor the better. The well casing may be “pickled” steel and if so you will need to use a bi-metal clamp to transition from the steel to copper. The key is surface area…. if necessary use some Penitrox, but make 100% sure you have a very solid connection as it can be under severe stress during a lightning event. Most of the energy during a lightning event will follow the “bond” you have created and not end up burning up your pump motor. I recommend you verify the service ground is 25 Ohms or less and the X/O bond is well made. The well casing will act as a shield (such as conduit can for the wire inside) and keep the energy away from the pump motor.


Part 2: Install a substantial (50-100kA per mode) TVSS at the well (my preference) or on the panel feeding the well. If the circuit is less than 40-amps (any single phase voltage) there are series installed TVSS rated at 72kA available.  You cannot have too much surge protection when lightning is involved. My own home has a well for irrigation I have a robust panel surge protector installed on the main panel and series connected on both my well and AC unit.


Our firm has worked with US Sugar, numerous growers and Bonita Springs Utilities to solve similar issues. If I can assist further please contact me.


One major grower we have worked with has over 200 wells. Most are three phase and over 100hp. Bonding the service entrance to the well casing along with surge protection stopped all but a very few of their pump motor damage issues.  US Sugar told me the combination all but stopped their damage and also significantly lowered their unexplained failures.


Nothing is “lightning proof” but I am sure you will see a significant lowering of the damage…….


John N. West, Sr.

Power & Systems Innovations, Inc.

P.O. Box 590223

Orlando, FL 32859-0223

Phone: (407) 380-9200

Fax: (407) 380-3911



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  • If the well casing is non-metallic,surge protector only is reuqired.

    T.M.Haja sahib
    Reply to this comment

  • Great advice on reducing well pump burn outs from lightning damage. I have used this method many times over the past 20+ years. As far as I know there have not been any failures due to lightning following the implementation of the above described grounding and TVSS installation.

    I would like to add three additional recommendations to the above and invite comment on both. 1. The 4/0 grounding/bonding conductor run from the service ground bar to the well casing should not be run in the same ditch or imediately parallel to the existing power cable or conductors feeding the pump motor. (Maintain a minimum three foot separation if possible) 2. The conductor should however be run generaly in a straight line between the two points taking care to avoid any sharp bends. (Lightning does not like to turn sharp corners.) 3. The connection to the well casing should be exothermic welded if possible. This will provide a lower resistance connection and should be maintenance free for many years. A lower cost option is to drill a hole in the side of the casing and tap thread it for a 3/8-16 bolt. Use a Grade 5, 3/8-16 by 3/4" bolt, flat washer and a lock washer to secure the 4/0 copper ground conductor to the casing using either a compression lug or mechanical lug rated for Copper. Clean thye connection site with a wire brush to remove any rust, apply on oxide inhibiting grease rated for use on copper connections to all parts during connection. Avoid the grey anti oxide grease that is primarily used on Aluminum which tends to harden and dry out over time.

    Comments/experiences Anyone?

    Thank you,

    Larry LeSueur CPQ, CBCP Barrett Woodyard and Associates Inc. Norcross, Georgia 30092 770-810-8800

    Larry LeSueur CPQ, CBCP
    Reply to this comment

  • I have hooked up heavy industrial machinery using 4 wire aluminum SER cable and every installation had ABSOLUTELY NO PROBLEMS with the aluminum wire.

    The first machine was a 60 KW plastics machine for squishing the tops and bottoms of PVC cooling tower cells. When is production, this machine ran 100% duty on half of the heaters and 90% duty on the other half of the heaters. There was enough cycling during lunch and bathroom breaks to prove that the terminals will not loosen up. This machine ran 24/7 for 6 months except tor Thanksgiving, Christmas, and the 2 times that the COPPER wiring in this machine broke down during the first 2 months of this machine's life.

    Since Ilsco Deox passed the 3 year salt spray test on the starter motor on the car, I inherited a stack of #220 silicon carbide abrasive paper from grandfather, and I had read Dr. Jesse Aronstein's early work on aluminum wire, I figured that I could do this in aluminum. I used Dr. Aronstein's recommendation of using the silicon carbide paper, elbow grease, electrical grease method on all of the wire strands. There are other issues such as overstripping the insulation so that I could use a screwdriver to establish a strand bending area, cutting off the sharp tips of the strands before scrubbing them, recompressing with a hose clamp, and using a file to chamfer the outer wire strands so that they will go into the lug better. You also need plenty of paper towels and something to degrease your hands and tools.

    Some other issues was that this project took place right after the stock market crash and copper inflation in October of 1997 and I was bringing 200 amps 240 volts corner grounded off of a busway that was in an attic. To make things more fun I had to use a 75 KVA transformer to step up to 480 volts ungrounded and ran #2 aluminum SER cable from there to this machine.

    For more details go over to my website at home dot eathlink dot net slash tilde mc5w . Dr. Aronstein's website is . Dr. Aronstein has also scientifically proven that a wire brush is 100% INEFFECTIVE at removing aluminum oxide from aluminum wire.

    You can also get lalluminum alloy weldment ugs from Sefcor that you tungsten inert gas weld weld to aluminum wire. You can also get copper lugs from Burndy that you exothermically weld to copper wire. Both kind of lugs are not tin plated because welding heat would destroy the plating. After the lugs cool you will need to use silicon carbide paper, elbow gease, and electrical grease to establish a connection that is free of copper oxide or aluminum oxide.

    Also, copper wiring that is out of doors will oxidize just as fast aluminum thanks to catalytic converters from cars. Not as bad as the amounts of ammonia as the air in a foundry has but still enough to mess up the wiring.

    I have seen more in the way of copper wiring burn up than aluminum. As far as I am concerned, if the lugs are big enough to accept aluminum wire I can do the work better than the way that most people do copper.

    Mike Cole mc5w at earthlink dot net Tel: 216-524-2185

    Michael R. Cole
    Reply to this comment

  • I have been installing and protecting submersible pumps for over 20 years. I am the person that Franklin Motor (the pump motor company) will refer you to for such problems. I have a system that has yet to be broken, yet as stated, nothing is perfect. My system is in my book Wiring A House. Basically it is as the previous comment has stated except that #2 is not an OR it is an AND. However, my grounding system is a bit more complicated as you see in the book. You can e mail me at or call me at 540-482-0109.

    Rex Cauldwell
    Reply to this comment

  • I have been a licensed master electrician in the state of Michigan and Wisconsin for over thirty years and I can not remember when it was not required by my AHJ that we bond all well casings that are within 100' of the service main. The distance being a factor in expense.

    Albert W. Ewaldt
    Reply to this comment

  • I agree with Mr. West in that "The energy in lightining is not predictable". My experience has been with submersible pumps not in casings, suspended from floating platforms. This type of application is common in the aggregate business (Quarries). Typically, these installations are in rural locations, at the "end" fo the power grid. I have witnessed catastrophic failure of motors, including rotor damage, not to mention motor control damage. Mr. West provides a strong argument for surge protection, and I thank him for it.

    Mark Prairie
    Reply to this comment

  • In the section Part 1, I don't understand how do you size the bonding conductor for the distance from the well casing to the main service ground if you are dealing with lightning and have no idea what type of amperage rating for bonding you are dealing with? I can understand how the larger the better but am lost as to how to get there.

    Pat Pappas
    Reply to this comment

  • I also encourage the use of the "free" grounding elecrtode a metal well casing provides. I am a firm believer in the use of exothermic welding in grounding applications. The illustration that the link take you to shows a metal plate arc welded to the casing (watch for the fumes from the zinc) with a #4 solid Cu welded to it. The exothermic weld gives the #4 tremendous current capacity though for larger services and greater distances I would also recommend a larger conducter. My experience is mainly with agricultural well with 10 or less HP pumps but this concept should scale up apply to large installations.

    The casing in the photo was about 65' deep and tested 2.7 ohms.

    Richard Currin
    Reply to this comment

  • John is correct, but if your well is some distance from your building's gounding electrode, a second method is the following. Drive a 10 foot ground rod, run a #6cu wire to the steel well casing ( attach as John described) and to the ( real important) equipment ground going to the pump. That way it becomes a secondary ground. We ground tall pole fixtures like this all the time. This should take care of any kind of transits running through the ground.

    Most wells in our area have concrete casing not steel. I wonder why in Florida they don't do the same.

    By the way we have over taken you guys this year in the number of lightning strikes. Not a record we are proud of. Good luck.

    Jim Yancey Code consulting Engineer NCDOI Raleigh, NC

    Jim Yancey
    Reply to this comment

  • Jim, you are welcome to the title of lightning capital. It is not as much fun as you may think. Cuts down on my afternoon fishing.

    The main reason the steel wells seem so popular down here is the depth they go to, often 400 feet or more. I know of two large wells that are just under 600 feet. Shallow wells are often nothing more than a 2 inch well point with 30-60 feet of PVC. They are most often for irrigation use only.

    In NC you have far better soil conditions for grounding. Florida in most areas is sand and every now an then a layer of limestone... in south Florida they have coral rock in some ares. That is a real stinker when you trying to ground a facility. I have done gounding work all over the USA and many projects out of the USA. Most of our work is high performance grounding and associated with the dissipation of lightning energy. Experience has shown me the lower the resistance and larger the wire at the service entrance the less energy you will see getting past the meter base and service disconnect. Given a low impedance and low resistance path much of the "lightning" energy will arc to ground. When you think about electrical panels, disconnects and switchgear every distance is a calibrated spark gap... give the energy you don't want in the facility a better path to earth and most of it will go there and the little left you can deal with very well by installing a proper system of TVSS devices. Our almost 15 years in business has seen this over and over with our customers. We have had meters come out of the meter base like birdshot... the disconnect melted and NO interior surge damage.

    My first well experience was with the well at my home in Longwood, FL many years ago (1976). It is a 170 foot deep well and steel cased. It was not bonded to the house and typical of many wells in Florida only the to phase wires were run to the well. I asked a fellow I knew then I fished with (retired master electrician from Chicago) what I needed to do after lightning took out the well. He told me to bond it with a "big wire" and he would install some MOV's. He had some large GE MOV's he purchased at a local electronics salvage store in Winter Park, FL. I lived in that house until 1986 and while my neighbors lost their wells due to lightning all I ever had to do is replace the MOV's a couple of times. The "fix" was crude, I used 1/0 I got at the same place he got the MOV's and buried it about a food deep in the yard and ran it the 40 feet from the well to the service entrance and he made the bond in my breaker panel. I worked for a company then that had very 4" bimetal clamps. We used 6 of them and spread the wire out to get a good bond, the pipe was black pipe and so we cleaned it and used Penatrox to insure a good bond. While it was not perfect it worked and lasted me for years.

    My goal in all this is to try to get people to understand the critical nature of proper grounding and bonding as it relates to lightning energy. Mike is the expert on the code.

    John West, Sr.
    Reply to this comment

  • A question/comment for John. Your information is excellent. Would you recommend treating the bonding conductor as a lightning downward conductor (ie. as if if were attached to a lightning rod)? In that I mean since it is in essence doing double duty would you avoid sharp bends in the installation? It would not matter much for fault current but it would reduce the effectiveness for lightning protection.

    Richard Currin
    Reply to this comment

  • Yes, Thanks for bring that up. The UL code and recommended practice (LPI) for bends in a lightning protection system is minimum for me. I have never understood why they would approve a "T" intersection of cables on a roof (I will not, we use double sweep bends) and yet they make a big deal of other bends. Any cable that is to carry extreem energy (most is not 60Hz) should be a gentle bend. I prefer a 18 inch radius... maybe a little over kill, but our customers don't have problems at all. Where possible a lightning protection system should be exothermic weld for any connection where it is possible to use it. That includes roof top systems. Most installing lightning protection systems treat them as installed and forget. Big mistake, I would bet that over 50% of the systems (I am sure it is much higher) are in very poor condition after 5-years. After all who do you know that does annual (at a minimum) system maintenance? That is about like buying a car and never checking much less changing the oil!

    Have a great weekend.

    John West, Sr.
    Reply to this comment

  • Richard... the wild card with any lightning event is no one knows what influence anything in the soil a tree root, an old pipe, sewer line, water line, a layer of very conductive soil, an underground sprinker control valve line... etc. Some days it is just a crap shoot.

    One service that we recommend for any critical site is a location service check the property near any building. A quick case in point. A very large beverage distributor (known as the "King of B.....) in this area had a very unpleasant experience. During construction the contractor ran a bundle of 250mcm into the building under the slab for construction power from the transformer. He just cut it off and filled the hole with concrete once he had power to the building. The end at the transformer was just buried. The run was over 1,500 feet. Guess what lightning found? It blew the concrete, tile, etc. out of the floor and jumped to a beam 4 feet away. The lady that sat at the desk was (Thank God) not in her seat. Several employees were hurt (not badly) but you know where it ended up.

    Any conductor that is expected to carry the excessive energy of a lightning strike should be treated as if it were exactly that, a lightning conductor.

    Old wires should NOT be left in the ground, building walls, ceilings, etc....


    John West, Sr.
    Reply to this comment

  • Mike, I have been told by several well contractors in our area that they do not want the well casing bonded to the electrical service as it creates some form of electroysis on the casing and rapidly deteriotes it. have you ever heard of such a thing?

    Joe C. Beta

    Joe C.
    Reply to this comment

  • If you have enough energy flowing on ground to eat up the well casing there is a flaw in the electrical system. I would start looking for an out of place neutral(s) or verify the neutral back to the power company transformer.

    The #1 reason below slab copper pipes get pinhole leaks is poor grounding and/or a poor neutral connection to the utility transformer. Without the issue of the poor neutral connection the low resistance of the pipes to earth and is often much less than that of the ground rod to earth. Guess where the majority of any ground current flows. In our area the power companies don't do any preventive maintenance on transformer bonds in residential neighborhoods. A poor neutral connection to the utility transformer plus a high resistance ground and under slab copper pipes will all add up to pipe failure in a hurry.

    Some critical sites monitor the resistance of their grounding and current flow on their grounding.... It is expensive $3k+, but the monitor will red flag any change and give you a chance to take corrective action before you have a disaster on your hands. It is much easier to keep the Ox out of the ditch than pull him out once he is in the ditch.

    I know of one case where the neutral wire was about to fail and the flow of current on the ground was significant. There was over 900ma flowing. The power company was called, they argued but in the end came and checked the neutral connection to find a flaw in the transformer bond. Guess what happened to the current flow on ground? It dropped to less than 9ma. This is a very large facility and while I would not be happy in some environments with 9ma I would be at this one......

    John West, Sr.
    Reply to this comment

  • I too have had several plumbers try and tell me not to ground a weel caseing-sorry they could not back their statement as to the effect that it will cause damage to the well! I believe that they should be bonded!

    Al Ewaldt
    Reply to this comment
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    Reply from: maxx-ev   
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  • What causes copper pipes that are coming up out of the ground to get pinhole leaks is that the basic environment of concrete corrodes copper over time particularly for an on grade slab building. Same goes for contact with limestone or coral in the aerobic zone of soil.

    Copper type K copper tubing sevices that come up through basement floors ( a lot of plumbers around here are afraid to run through the concrete block wall ) do not seem to be a problem here in the Cleveland, Ohio area.

    Actually, if a pump circuit is really critical it should be in XHHW-2 or ethylene propylene rubber version of RHW-2 inside of galvanized steel or brass conduit. There should be both an internal equipment grounding conductor and an external bare FAT conductor that is a grounding electrode conductor for the service equipment and/or motor controller. Better yet, the conductors should be type USE or UF as well inside of the conduit for extra ruggedness. Federal Aviation Administration does not allow the use of THWN wire for 120 volt and 277 volt airfield lighting circuits partly because THWN is less resistant to lightning.

    There is also a drawing in Army Technical Manual 5-690 for protecting and underground electrical line or oil pipeline from lightning ground currents. This consists of burying a fat bare copper conductor a certain distance above the underground line and burying the line and the fat bare copper wire at certain depths. This was something that was worked out by Bell System and the oil companies and there is a similar drawing in an issue of the Bell System Technical Journal but Army Technical Manual 5-690 is easier to find using Google and has lots of drawings of what a proper lightning rod system should look like.

    Mike Cole, mc5w at earthlink dot net

    Michael R.Cole
    Reply to this comment

  • I forgot to mention that any metal conduit that goes out to the well should be about 2 sizes larger than what NEC requires to reduce wire pulling effort. If you need a smaller size going into the top of well cap a handhole will solve that problem.

    It is actually more economical to use 2.5 inch schedule 80 PVC conduit for a 200 amp single phase underground service that uses 4/0 aluminum URD cable inside than to use what NEC allows. This is because it is not possible to hook up a forklift truck or a station wagon to do the wire pulling.

    Michael R.Cole
    Reply to this comment

  • If you're going to run Al conductors, don't forget to re-torque them every six to twelve months. And if you want to use Al conductors I wouldn't use a cable assembly, but rather individual conductors. Individual conductors will pull easier through a conduit.

    But how would I know, we won’t use Al conductors. We leave the Al wire for utilities, Wal-Marts, and other cost cutters.

    Besides, when you go with copper, a 3/0 has a 200-amp ampacity instead of 180 and only about 77% of the resistance that creates the voltage drop you’re sizing for. In fact, if you’re sizing up for voltage drop, then a 2/0 copper would only have 96.7% of the resistance of the 4/0 aluminum.

    Yes, anything with aluminum conductors is cheaper. But I don’t think that is what this discussion started out with – being cheaper on the install – but rather being cheaper in the life cycle. , including the life cycle costs of the connected equipment.

    Assuming you’re using 4/0 Al for voltage drop and not just a cheap household service, a better design is 2/0 copper in 2-inch conduit. Whenever you jump conduit sizes above 2 inch the price jumps quite a bit.

    But if this is just a 4/0 Al household service and you’re only trying to sleeve the 4/0 cable from a direct bury trench to a meter socket and/or disconnect and/or LB and/or whatever, the cost difference for a single stick of 2.5 inch vs. 2 inch is very small. But it is large when you have the utility installing the underground, as we have for the most part in Central Iowa

    If you are talking about the branch circuit from the main building to the wellhead and the entire run is in conduit, then look at the new smaller tuggers that are out now. We own one of the original Greenlee Little Tuggers and a Maxis Pull-it 3000. Both units are quite nice and very economical if you pull even a few pulls a year. And we all have generators if power is not available on site.

    Matthew Hermanson
    Reply to this comment


    Reply to this comment

  • I forgot to also mention that surge arrestos for well pumps or any other motor need to be on the load side of the motor controller. Since the vast majority of single phase and just about all 3-phase pump controllers open all of the conductors, a surge arrestor that is on the supply side of the controller WILL NOT PROTECT the motor when the controller is in the off state.

    Also, when the controller is in the off state the motor circuit is in the ungrounded condition and therefore is subject to static electricity buildup from Saint Elmo's Fire and other low energy lightning. Dp not depend upon the surge areestor for this - there is a 200 volt to 800 volt gap between the 30 minute voltage withstand rating of a 480 volt motor and the clamping level of an arrestor that is rated for 480 volts ungrounded. Same can be said for just about any other voltage.

    What you need are some high value resistors connected from each phase on the load side of the motor controller to ground. What an old Audel electrical book recommended for 480 volts ungrounded were 1 megOhm 5 Watt resistors.The 5 Watt rating is needed to withstand ferroresonant overvoltage. What you can get from Newark Electronics are 240,000 Ohm 3 Watt metal film resistors and connect them in series string as follows:

    3 resistors each phase to ground for 240 volts 4 resistors each phase to ground for 480 volts 5 resistors each phase to ground for 600 volts

    The peak voltage rating of a 240,000 Ohm 3 Watt metal film resistor is 750 volts, which will coordinate with the clamping level of arrestors that are rated for ungrounded, corner grounded, resistors grounded, and well as arrestors for solidly grounded systems.

    Mike Cole mc5w at earthlink dot net

    Michael R. Cole
    Reply to this comment
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