above ground motor/pump units are connected to metallic pipes going into the earth.
Well you do now. It is a safety thing. In case anything in the motor comes lose it goes to ground and blows the breaker. An ungrounded case that becomes energized without a ground is a trap waiting for the first person to come along and touch it completing the circuit to ground.
If a submersible pump is hanging under ground in a hundred feet of water, even as a safety issue attaching a ground is a bit redundant. It’s now required however so it’s done every job.
The net result for me is the pumps properly grounded to the top of the well are now more susceptible to lighting damage. The metal casings on wells are hit by lightning all the time. That energy has plenty of time to dissipate before reaching the pump. Now since the ground wire is attached at the top of the casing the lighting has a direct path to the motor.
On the plus side the world is now safer for people working on the equipment in instances where the water level is somehow below the motor in the well while powered or you somehow manage to find ground water that has limited conductivity.
That would seem all the more reason to connect the pump ground to the electrical service ground, although for a submersible I can see that the shorter path to ground would be to the pump, or rather to the water. Surely there are things higher up that would be struck first.
My well casing is PCV, btw. Why metal?
On a new installation the ground runs from the house to the top of the well then is bonded to the top of the well and continues to the pump. So yes the pump is attached to the electrical ground. The well casing itself is a much better ground then most homes have for their electrical systems anyhow. Lightning takes the best paths to ground not necessarily the shortest. As the well casing is an excellent ground the lighting will skip out on a 30foot house or tree, which are poor grounds, and hit the 18inch high well casing. Personally even knowing the damage it can cause to the pump I’d much rather the lightning hit the well out in the yard rather then the house, so a steel casing in such instances is a perk not a disadvantage.
I might be blowing lightning damage out of proportion however, I see lightning damage semi-frequently because I work will wells and electrical. The average home owner probably never sees lightning damage to their home.
There are a number of reasons not to use PVC casing. I can go into more detail on other reasons but the chief among them is it cracks. In new England it isn’t practical at all. The rocky soil almost guarantees it will fail. The more appropriate Question is why PVC, the only answer on that tends to be because it’s cheaper. I know of no companies in my area that use PVC casing. Whenever I have seen it the driller is gone and nowhere to be found. They tend to be fly by night companies from out of state.
The casing only goes from the top of the well to about 15feet into the bedrock(on good wells cheaper well use less) So the casing only makes up a small percentage of the actual well. The cost difference ends up being a few hundred dollars. When spending 10k for a new well installation and service I find it is incredibly poor practice to use a cheaper product on something so integral to the well.
I will get underbid by guys willing to cut corners like that to offer lower bids, I happily accept that and know I will never have to explain to a customer their multi-thousand dollar investment is shot because I chose the cheapest option.
Wow.
I have a shallow well above ground pump. 110v motor and grounded to the electrical ground.
Shale here, at three feet. Nothing to damage PVC.
For a cite, look at the printing on any piece of pre-made cable, like NM (Romex).
You will see something like NM-2 W/G, meaning Type NM cable, 2 conductors, with ground. They count only the 2 conducting wires, not the ground, which is listed separately.