What Electrical Voltage Works Best for Most Pumps?

We get calls every day for emergency service, which we take very seriously.  Unfortunately we have to charge for this service, and most calls could have been prevented.  So, What Electrical Voltage Works Best for Most Pumps?

What I am referring to is electrical failure of the water system.  You see, to get “free” water from the well, you must provide some sort of electrical service.  These types of systems vary according to the requirement of the motors.  I have worked on pumps than ran off of solar power, generator power, three phase power, and single phase power.  Most small water systems used for residential water supply use single phase power.  This article will address this type of power only.

Single phase power systems date back to a time before we had a lot of technology we have today.  The power company puts out power in very high voltages in order to travel long distances with relatively small wires.  Electricity is similar to water or any fluid in that it is prone to drops in power due to too much friction loss (too small of a conductor wire).  Hopefully the power grid you are on does not have any major issues with voltage drops, but we have seen power grid issues cause problems for pumps before, although not as likely.  A licensed electrician could easily test your home to detect power grid issues before you install your pump system.  Another good test an electrician can do, while he is there, is to check the ground rod for your home.  As more things in the home use computer driven circuits, the more the ground becomes critical.  If you have very sandy soils, grounding may be an issue.  We actually drill wells to make a really reliable grounding for computer companies such as Google.  Trust me, grounding rods are not always making a good ground as you may assume.

The biggest issues we see are related to pressure switch failures.  A pressure switch is very similar to the light switch you use to turn on the lights in your home at night.  It has a set of contacts that closes the circuit upon water demand.  What creates premature failures is heat and wear.  You would probably expect a failure after 20 years or so, but every year?  We see this a lot.  It is due to the under-sizing of a water tank, or improper installation of a water filtration device.  Or using 115 volts for a larger type of motor.  Let’s focus on 110 volt service related to pumps.

Rule #1.  Never, ever use 115 volts to drive a pump motor, unless it is for your sworn enemy or your mother-in-law!  I am just kidding…not about the 115 volts, but about the sworn enemy thing.

Rule #2.  You must always provide a dedicated circuit (no matter the voltage) for any pump motor.  If you have two pumps, you must have two separate circuits.  The only exception may be a booster pump that runs in sync with the main pump.

We see a lot of pumps that run on 115 volts and share a circuit with a refrigerator or other appliance.  This is improper, and is actually a fire hazard.  Don’t expect that fridge to stay running when the breaker finally pops due to the pump and the fridge turning on at the same time.  Also expect on or the other to fail prematurely.  I could get into all the electrical lingo, but suffice it to say that it is not good.  One of the biggest reasons people say that they stick to 110volts is that they claim a Generator has 115 volts on it.  Most have never even tested their generator to see if it will run the pump (which most of the time the generator is one of those cheapie 2500 watt deals).  Suffice it to say that a good generator has 230 volts and usually if it does, it is of sufficient size (3500 watt minimum for 1/2 hp).  We recommend a 5000 watt surge for a one hp.  These are relatively inexpensive, and you can buy a 230 twist type plug and make a “pigtail” connector, just like a 115v has!  Years ago, I used to have an adapter on the generator to run a “regular” extension cord over to the pump in order to test it with 230 volts.  I had a label on the outlet that had a skull and crossbones and said “For well driller use only”.  The electricians used to laugh, but they thought it as pretty slick!

Our company policy is that all electrical items have no warranty.  I did this years ago due to so many people using 115 volts.  If you have 230 volts, which is proper, and a switch that we installed less than a year ago fails, assuming all other parameters are correct, we will warranty it.

I go to so many systems where people say, “It worked that way for 30 years”.  I understand that, and I will install it with a disclaimer!  I have only 25 years of experience doing this job and every motor manufacturer backing me up with proper electrical design, and so just sign the disclaimer and move on!  I don’t like arguing, especially when I know I am right…

A good example of this is a recent job where the gentleman’s well went dry, and we had to do an emergency well replacement.  This is for a shallow well, where a deep well would be so salty you couldn’t drink it.  The shallow water quality is fairly good, but you have to move around to find it.  We drilled the first hole next to the old well, and we could not find any water.  We moved 200 feet away and found 15 gallons per minute.  That was more water than he had ever had out of the old well.  Since this was an emergency and they had been without water for some time, he asked me to move his old pump and tank and re-install it close to the new well.  We did just that, and in order to get the water back to the home, we had to trench 200 ft and place pipe in the ditch.  We told him that a second ditch was needed for us to install the electrical, and he hesitated and said he would take care of the wire.  He installed the wire in the same ditch.  Our people made the tie in for him to expedite the job, even though we don’t technically do electrical.  We did tell him that the voltage demand was too much for the wire size and distance @115 volts (remember the extra 200 ft).  We told him that converting to 230volts was essential, but that was going to require a major rewire of the breaker box (trust me, we know all the tricks), and we don’t rewire breaker boxes, but we could refer an electrician.  Again he balked.  So we hooked it up, and surprisingly it worked!  Three months later he called and said the pump was kicking the breaker, and we should come immediately since we drilled the well and had moved the pump.  I told him that I had only moved the pump and run the wire and he had taken responsibility to hire an electrician, and a breaker kicking was not a well problem, it was an electrical issue.  I told him we would come and diagnose, but that it would cost an emergency service call, since he wanted us immediately.  He was not happy.  We had a signed contract backing us up.  He had no good argument for us when we reminded him of the contract.  Don’t be like that guy.  Listen to what we tell you.  Minimum standards are just that, the least you can do to make it work properly.  We prefer to refer an electrician and let him deal with it, since electrical work is not our specialty.

The proper voltage for any residential pump is 230 volts.   I am aware that they do make a 115 volt non-convertible submersible motor, and I avoid it like the black plague!  It does not last very long as opposed to a 230 volt submersible.  Heat is the issue, and unless you are willing to buy a very large tank to keep the motor as cool as possible, we will not sell one of those voltages.  Wire size and amperage of the breaker is based on the size of the motor.  For example:

Well pump is 400 ft from house (due to septic system or some other issue), and you need to know how big the wire needs to be and what size breaker.  The motor is a one HP that pulls 8 amps.  Wire should be sized 10 gauge/4 strand.  Breaker disconnect installed next to pump for ease of control.  A 12 gauge jumper wire may be used to pump (less than several feet) to make pressure switch wiring easy.  The breaker will be a 20 gauge double circuit (220v). We also recommend a separate grounding rod.

Common mistakes with this scenario is 12 gauge wire which is too small, and 110 volts which is just plain crazy.  Also the 10 gauge wire may trigger an uninformed electrician to install a 30 amp breaker since it is usually the size breaker for that size wire.  To prevent this, communication with electrician is needed or use a #12 jumper between breaker box and side of house where trench begins. If you hire us, this is how we roll! LOL…

I guess the funniest thing I have ever heard, was a guy called up during a recent snow storm where the power lines had failed and said he had purchased a “solar powered” generator that utilized a car battery, and he couldn’t understand why he couldn’t get water out of the pump.  Come to find out, he had ran an extension cord to the well pump and plugged it into a 1000 watt inverter (darn Northern Tool!).  I couldn’t help but laugh, but I offered him the use of my generator since he was trying to get water to supply a home which had an elderly mother.  Thankfully the power company came just as I was leaving to take the generator!

Thanks for reading,

Jody