Protecting submersible pump from lightning transients

Discussion in 'Pumps and Tanks Well Forum & Blog' started by Arky217, Oct 20, 2013.

  1. Arky217

    Arky217 New Member

    Messages:
    43
    Location:
    Arkansas
    My well has a pvc casing, the pump will be a 2 wire.
    Typically, the ground wire from the pump would be connected to the grounding bar in the service panel.

    Well, my service panel ground runs to a 8' driven ground rod about 6' feet away from the house,
    however, since the location is on a ridge, the soil is very rocky, hence probably not making an ideal earth ground.
    For that reason, I continued the ground wire to a second 8' driven ground rod a short distance away.

    For lightning protection for the pump, is there a better way other than just connecting the pump ground wire
    to the grounding bar in the service panel ?

    My well driller recommended that I drive a ground rod near the well head
    and tap into the ground wire going to the pump at the well head.

    But I really don't see where that would add any additional protection
    above the already 2 ground rods near the service panel.

    Another suggestion would be to attach a surge arrestor to the pump's two hot wires at the service panel.

    Still another suggestion would be to just turn the pump's breaker off during a storm.

    Since the well casing is pvc, what would be the most effective way to protect the pump from lightning transients ?

    Thanks,
    Arky
  2. valveman

    valveman Moderator Staff Member

    Messages:
    4,486
    Location:
    Lubbock, Texas
    A ground wire, several ground rods, lightning arrestors, and turning off the breaker are all good ideas. Do as much as you can because if Mother Nature wants to get that motor, there is not much way to stop her. I have seen wells in the middle of the field with no electricity going to them and the wires not attached to anything, and they still get hit by lightning. They tell me lightning doesn’t even have to hit the wires. It can hit the ground ½ mile from the well and still get the motor.
  3. LLigetfa

    LLigetfa DIYer, not in the trades

    Messages:
    4,052
    Location:
    NW Ontario, Canada
    If you did that, by code you would need to run #6 wire from those rods back to the house. There is no benefit to having the rods closer to the well than to the house. You may as well drive those extra rods somewhere closer to the house. The lightning surge would be coming from the panel so closer to the panel is better.

    Generally speaking, you cannot have too many ground rods. I've worked on jobs where we were grounding towers and had as many as 50 rods in the ground.
  4. craigpump

    craigpump Member

    Messages:
    970
    Location:
    ct
    I dont know if it was the galvanized pipe or poor lightning arrestors, but I remember as a kid when there was a lightning storm we would be crazy busy for days.
  5. cacher_chick

    cacher_chick Test, Don't Guess!

    Messages:
    3,249
    Location:
    Land of Cheese
    I know of several homes that had well pump replacement paid by their homeowner's insurance due to lightning strikes.
  6. craigpump

    craigpump Member

    Messages:
    970
    Location:
    ct
    In the past few years insurance companies have been scrutinizing claims about pumps being hit by lightning. I have seen them reject claims unless there has been additional damages, TV's, computers, etc.
  7. westom

    westom New Member

    Messages:
    11
    Location:
    nja
    First understand why a pump is damaged. Lightning is an electrical connection from a cloud (maybe three miles up) to earthborne charges (maybe four miles distant). Lightning does not go five miles across the sky to connect to those charges. It takes an electrically shorter path 3 miles down and four miles through earth.

    If that path goes into AC power lines and out to earth via the pump, then a pump is damaged. That electric current path can be on any of three wires into the pump. Grounding one wire does not solve the problem.

    Best is to connect, low impedance, all AC wires to earth. One already is. But a lightning strike to AC wires far down the street can be incoming on those other AC wires, through the breaker box, into the pump, then destructively out of the pump to charges maybe four miles distant.

    You must earth a surge BEFORE it can enter a house or pump. Those other wires cannot connect directly to earth. That is what effective protectors do. Effective 'whole house' protectors have a dedicated wire to make a low impedance (ie 'less than 10 foot') connection to earth. These protectors are completely different from plug-in type protectors that do not have and will not discuss earth ground. Protection for a pump means earthing a surge BEFORE it even approaches the pump.

    Lightning (as true of other typically destructive surges) can be 20,000 amps. So a minimally effective connection to earth (ie 'whole house' protector) is 50,000 amps. Because effective protection means that connecting device is not damaged. Companies with better integrity provide these including Leviton, Polyphaser, General Electric, Syscom, Intermatic, Ditek, Siemens, ABB, and Square D to name but a few. A Cutler Hammer solution is available in Lowes and Home Depot.

    Best protection is a wire that connects directly to earth. To have same protection on all wires means those other wires must be connected just a short to earth via a protector. Effective protectors only do what a wire would otherwise do better.

    Protection is defined by the connection to and quality of earth ground. If any incoming wire does not have a low impedance (ie no sharp wire bends, no splices, less than 10 feet, etc) connection to earth, then protection is compromised.

    A surge, connected better (ie shorter) to single point earth ground, need not use a pump as a connection from cloud to distant earthborne charges.
  8. valveman

    valveman Moderator Staff Member

    Messages:
    4,486
    Location:
    Lubbock, Texas
    I use to inspect motors for a couple of insurance companies. If it is only electrical failure, no heat damage from a lack of flow, then it is hard for them to argue it was not lightning. However, a hole blown through the motor about 2” below the lead connection makes it a lot more obvious lightning had something to do with it.
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