Better lightening protection for a well pump?

[The_Eric]

Well we came back from out of state this weekend and were greeted with an out of order well pump.. of course I didn't find out until I had my hair full of shampoo and the shower petered out Evidently we had a strong storm move through with lots of rain and lightening. It ended up knocking out our VFD for the pump motor... This is the second time in 3 or 4 years it's happened and I'd like to see to it that I am better insulated from such happenings. Currently we have some little short cylindrical doohickey tied into the line out from the breaker box.

is there a better approach? Fast blow fuses in place of the breaker or a different arrestor? The VFD was around $2800 a couple of years ago, so I shutter to think what it'll be now... At least my home owners insurance will cover it.

 

[Rand]

For additional lightning protection... Whole home surge protector?

for Lightening protection blocks of concrete so it doesnt lift off (joking)

I'm assuming this VFD is in the basement not sure it matters if the pump is submerse or jet.

 

[Chris142]

What's a vfd?

 

[brianl703]

Is it a Grundfos SQE pump?

I installed a surge protector on the SQE control box in the basement, in the circuit between the control and the pump.. The surge protector I used is a GE Tranquell which mounts into a knockout and has 3 wires, two hot and a ground. Similar surge protectors are used with air conditioner units and one of those would work fine.

At the well end, I used a well pump surge protector, again with 3 wires, two hot and a ground. This surge protector was small enough to fit inside the junction box on the well casing sticking out of the ground.

Never had an issue with lightning.

 

[Fla]

For additional lightning protection... Whole home surge protector?

for Lightening protection blocks of concrete so it doesnt lift off (joking)

I'm assuming this VFD is in the basement not sure it matters if the pump is submerse or jet.

The power company is my area has been trying to lease those to their customers for years but I don't know of anyone that has taken them up on it. IIRC the costs was about $7 or $8 per month but that was about 25 years years ago. Call your power company and ask.

And while you're at it, asks what kind of warranty they give you against damage to YOUR equipment if their surge suppressor doesn't do it's job.

A simple surge protector is just a single MOV and you can buy them from DigiKey and the like for a few dollars. But MOVs come in a WIDE range of power handling capabilities and you need a high powered one and not just the cheapest thing on the market such as what's used in the typical power strip surge suppressor. Ideally the surge suppressor for your well should have a MOV (or MOVs) across L1 to L2, L1 to Ground and L2 to Ground and Neutral to Ground. I have a few high powered commercial units that I've torn down and they typically have four large MOVs in parallel across all four circuits (16 MOVs total). When looking at surge suppressors, ignore any voltage or amperage claims. What you're looking looking for is Joules, i.e. the amount of Power, that they can handle.

A final note: when MOVs get a high enough voltage, they SHORT; often permanently! That's how they protect the devices downstream of them. So your supply circuit has to be able to handle that and MUST BE properly fused or have a fast acting circuit breaker on it. If it doesn't then it can overheat the wiring. Possibly enough that it can even start a fire. Needless to say, everything has to be very well enclosed in a heavy duty fire proof box and all the wiring from the power panel to the surge protector needs to be enclosed as well.

MOVs will often short out and absorb ALL of the energy in a lightning strike or a power surge and they frequently explode because of the amount of energy involved. The units that I have were housed in well made steel cases packed with dry sand to help absorb the potential blast.

 

[Fla]

The power company is my area has been trying to lease those to their customers for years but I don't know of anyone that has taken them up on it. IIRC the costs was about $7 or $8 per month but that was about 25 years years ago. Call your power company and ask.

And while you're at it, asks what kind of warranty they give you against damage to YOUR equipment if their surge suppressor doesn't do it's job.

A simple surge protector is just a single MOV and you can buy them from DigiKey and the like for a few dollars. But MOVs come in a WIDE range of power handling capabilities and you need a high powered one and not just the cheapest thing on the market such as what's used in the typical power strip surge suppressor. Ideally the surge suppressor for your well should have a MOV (or MOVs) across L1 to L2, L1 to Ground and L2 to Ground and Neutral to Ground. I have a few high powered commercial units that I've torn down and they typically have four large MOVs in parallel across all four circuits (16 MOVs total). When looking at surge suppressors, ignore any voltage or amperage claims. What you're looking looking for is Joules, i.e. the amount of Power, that they can handle.

A final note: when MOVs get a high enough voltage, they SHORT; often permanently! That's how they protect the devices downstream of them. So your supply circuit has to be able to handle that and MUST BE properly fused or have a fast acting circuit breaker on it. If it doesn't then it can overheat the wiring. Possibly enough that it can even start a fire. Needless to say, everything has to be very well enclosed in a heavy duty fire proof box and all the wiring from the power panel to the surge protector needs to be enclosed as well.

MOVs will often short out and absorb ALL of the energy in a lightning strike or a power surge and they frequently explode because of the amount of energy involved. The units that I have were housed in well made steel cases packed with dry sand to help absorb the potential blast.

PS I just happen to have a small commercial surge protector laying on my desk when I wrote that. I looked and it has four LS40K550QP MOVs in it. Evidently these are for a 440 volt circuit and the MOVs are rated at 960 Joules each. See here.

 

[Langanobob]

What's a vfd?

Variable Frequency Drive. They allow speed control of 3 phase motors and some can be used to power 3 phase motors with single phase electricity.

 

[Fla]

What's a vfd?

Probably Variable Frequency Drive. It lets the pump speed up and slow down depending on the demand. VFDs are more energy efficient than stopping and starting motors.

 

[Fla]

Variable Frequency Drive. They allow speed control of 3 phase motors and some can be used to power 3 phase motors with single phase electricity.

Most purposely built VFD drive motors have a lot more than three phases. I've torn down a couple that has 12 sets of windings in them and IIRC my Mitsubishi Mini-split AC is also 12 phase.

 

[jhs914]

I had problems with power surges from lightning strikes knocking out equipment (not my well pump). The last repairman suggested I check my ground rod that connects to the power meter. Sure enough when I dug a foot down I found that the idiot electrician that installed it just buried the ground wire with no ground rod. After I drove an 8 ft ground rod and attached the ground wire I have not had any more problems. I also had the power company install a surge protector at the meter so that helped also.

 

[brianl703]

I had problems with power surges from lightning strikes knocking out equipment (not my well pump). The last repairman suggested I check my ground rod that connects to the power meter. Sure enough when I dug a foot down I found that the idiot electrician that installed it just buried the ground wire with no ground rod. After I drove an 8 ft ground rod and attached the ground wire I have not had any more problems. I also had the power company install a surge protector at the meter so that helped also.

Electric codes require 2 grounds (with one exception), so there should have been another ground (usually a water pipe, if city water with a metal incoming water pipe).

The exception is an Ufer ground or CEE ground (concrete encased electrode--a connection to the rebar in the foundation).

 

[doitmyself]

Most purposely built VFD drive motors have a lot more than three phases. I've torn down a couple that has 12 sets of windings in them and IIRC my Mitsubishi Mini-split AC is also 12 phase.

I think Laganobob is talking about 2 phase vs. 3 phase electricity, while you are referring to the number of submersible well pump stages, which can be anywhere from 5 to well over 20.

@ The-Eric, I just replaced a Franklin VFD on my workplace irrigation well for just over $4,000 (ouch).

Off Topic: We also had to replace the well pump and pipe (100') for severe corrosion after only 13 years. We think it might be from severe hard water and/or some sort of electrolysis/stray voltage was occurring. The new pipe is pvc, with a doohickey that prevents pump torque twist. This replacement work cost more than the entire well install 13 years ago. Yes, inflation is wicked.

 

[jhs914]

Electric codes require 2 grounds (with one exception), so there should have been another ground (usually a water pipe, if city water with a metal incoming water pipe).

The exception is an Ufer ground or CEE ground (concrete encased electrode--a connection to the rebar in the foundation).

No city water. I am on a well and the pipes running to the well are PVC. I could only find one ground wire and it was the one without a ground rod.

 

[brianl703]

No city water. I am on a well and the pipes running to the well are PVC. I could only find one ground wire and it was the one without a ground rod.

I think the option there is to install two ground rods, 6 feet apart (unless the impedance to ground on the single rod is less than 25 ohms; not sure how this is tested, I don't think most electricians bother and just install two grounds).

 

[Cujet]

I have multiple surge protectors including one on the main for general lightning protection, and one in the CB box to limit current. There is an art to the science and some types can be used together. I have read that one should stick with the same brand.

Possibly of interest, the one on the main required a straight wire run to the ground rods! No bends or kinks. Apparently, the bolt's surge will only follow a straight run.

Surge protective device types | SPD type 1,type 2,type 3,type 4

Learn different Surge protective device (SPD) types viz. type 1 surge protector,type 2,type 3 and type 4 surge protector.Explore functions of SPD types viz. GDT (Gas Discharge Tube),TSPD (Thyristor Surge Protection Devices),TVS(Transient Voltage Suppressor),MOV(Metal Oxide Varistor),PESD...

www.rfwireless-world.com

 

[Number_35]

I think the option there is to install two ground rods, 6 feet apart (unless the impedance to ground on the single rod is less than 25 ohms; not sure how this is tested, I don't think most electricians bother and just install two grounds).

When the electrical utility I worked for did ground rod testing, we found there was very little advantage to having two ground rods when they were spaced 3 m (10') or less apart.

When the separation was increased to 6 m (20') or greater, the effective ground resistance dropped quite a bit.

As far as achieving 25 Ω goes, that will vary greatly with ground conditions. Wet soil with lots of dissolved minerals will offer low resistance. Bedrock is high resistance. Sometimes a GEM (ground-enhanced material - basically cement powder with conductive material added) is added to lower resistance.

Even in high-resistance areas, the important thing is to achieve a relatively low resistance compared to the surrounding area, so that fault current or lightning will take the preferred path to ground. 100 Ω is low compared to 10 kΩ.

 

[Number_35]

I have multiple surge protectors including one on the main for general lightning protection, and one in the CB box to limit current. There is an art to the science and some types can be used together. I have read that one should stick with the same brand.

Possibly of interest, the one on the main required a straight wire run to the ground rods! No bends or kinks. Apparently, the bolt's surge will only follow a straight run.

Surge protective device types | SPD type 1,type 2,type 3,type 4

Learn different Surge protective device (SPD) types viz. type 1 surge protector,type 2,type 3 and type 4 surge protector.Explore functions of SPD types viz. GDT (Gas Discharge Tube),TSPD (Thyristor Surge Protection Devices),TVS(Transient Voltage Suppressor),MOV(Metal Oxide Varistor),PESD...

www.rfwireless-world.com

A bend in the ground wire adds inductive reactance - think of it as part of a coil. Any bend should have as large a radius as possible.

To use a mechanical analogy, the train is way less likely to come off the track if the track is straight.

 

[Number_35]

High-frequency current (such as is generated by a lightning strike) tends to travel on the surface of the conductor rather than inside it.

To maximize surface area, a braided conductor comprising many fine strands is best.

A stranded ground cable is preferable to a solid one.

 

[Fla]

High-frequency current (such as is generated by a lightning strike) tends to travel on the surface of the conductor rather than inside it.

To maximize surface area, a braided conductor comprising many fine strands is best.

A stranded ground cable is preferable to a solid one.

Ever go look at the ground wire on a meter on a house or on a power pole?

 

[dlundblad]

Ever go look at the ground wire on a meter on a house or on a power pole?

I have never seen a grounded meter base.

I can’t speak for the high voltage applications, but typically Romex wire is stranded when it’s smaller than #10. I have seen solid on wooden poles and stranded on the steel poles though.

I can’t imagine unspooling and working with solid #6, which would be the grounding conductor for a 200 amp residential service.