Water Pump Wiring Troubleshooting & Repair

Well pump wiring diagrams, 3-wire, 4-wire,
Install or detect & fix well pump control box
2-wire, 3-wire & 4-wire pump installations

How to test a submersible well pump wiring and motor - typical resistance values

If you think the well pump motor is overheating or is damaged and is drawing high current (amps) there are at least two common electrical tests:

1. A test of the pump wiring

itself for deteriorated or damaged insulation (low resistance), breaks (infinite resistance), and dead shorts to ground (zero or close to zero resistance).

We do this with electrical power OFF and the pump wires disconnected; then each wire is tested for continuity and resistance by measuring ohms (resistance) across the wire, between the wires, and between the wire and ground.

See more details at ELECTRICAL CIRCUITS, SHORTS 

2. A test of the pump motor windings

for evidence of wear or shorts (abnormally low resistance)

Tests of the pump wiring are made by individually connecting between each wire (at the well head) and ground.

If the well casing is metal then connect the ground lead of the VOM/DMM (be sure it's a good clean connection) to the well casing or metal piping).

If the well casing is plastic then you have to connect your ground lead to the circuit ground.

In the photo just above I'm using my Sperry DSA-500 Digisnap multimeter in AMPS set to the 40A AC; the stovetop circuit I'm measuring (not a well pump) is drawing 0.11 Amps.

I give some examples below.

It's difficult to make an exhaustive check of the wires for leaks or weak shorts to ground without pulling the wiring out of the well since at the wire ends there will be a connection through the pump motor - giving some resistance but not a quantity that we know without help from the pump manufacturer.

Watch out: if you do not know how to perform electrical wiring and circuit tests safely you could be shocked or killed or could start a building fire. Work with power off and disconnected from the pump circuit.

See DMMs VOMs SAFE USE OF

With power OFF and wires to the pump DISCONNECTED at the house end so that there is no power to the pump or controls,

AND provided you know how to use a DMM or VOM safely - as you could be killed if you make a mistake in wiring -

you or your electrician might use the DMM or VOM in Ohms mode to measure the circuit resistance.

You need to know the normal resistance for your specific well pump brand and model.

\Illustration: a waterproof electrical wiring splice kit sold at Home Depot stores, electrical suppliers, plumbing suppliers.

You need to know the approximate total length of the wire as there is a correction factor to include for wire length.

• Before allowing for wire length, for EXAMPLE, a #10 copper pump wire will have about 0.214 Ohms of resistance for each 100 feet of a pair of leads to the pump.
• A new motor without the cable will have about 20 MegOhms resistance and a used motor that's still serviceable may drop to 10 Megohms.
• A new motor in the well along with the drop cable will show about 2 Megohms resistance. (2,000,000 Ohms)
• Or in general, with the motor in the well you will see 0.5 to 2.0 MegOhms resistance (500,000 to 2,000,000 Ohms).
• If the well pump motor has been damaged Goulds notes that you will see much lower resistance, maybe in the 10,000 to 20,000 Ohms range
• If the well pump motor is dead or the wiring insulation has been destroyed you will see less than 10,000 Ohms resistance.

You can also check resistance between each lead and ground - and to the well casing as sometimes that will show up a short not between wires but between one wire and ground.

Details of testing for shorted or open electric motor windings are given at

• ELECTRIC MOTOR DIAGNOSTIC GUIDE
• ELECTRIC MOTOR WON'T START / RUN

and if your pump motor uses a motor start and run capacitor, those tests are at

• TEST a MOTOR START or RUN CAPACITOR 
  
  Goulds Pumps, an ITT company, offers an excellent submersible well pump diagnostic and service manual.
• SINGLE PHASE PUMP SERVICE MANUAL [PDF] (2005) Goulds, ITT, Website: www.goulds.com available from the company or free as a download at InspectApedia

See pages 24 and 25 therein for notes on how to make a resistance check of the pump wires.

The illustration I show above is excerpted from Gould's pump manual

Well Pump Trips Circuit Breaker

The 20amp pump circuit breaker keeps being thrown: How do I check for a short in the pump wiring?

An InspectApedia reader asked:

I have a 240 V submersible well pump that has worked fine for almost 2 yrs but now the 20amp breaker keeps being thrown, but at different intervals.

It may run all day or it might trip in 5 mins.

How do I check the wires to see if there's a short between house and well or if the short is in the well itself? The wire from the house is buried really deep. On 2018-12-26 by Anonymous -

Well Pump Keeps Tripping the Circuit Breaker

And InspectAPedia reader Joe said:

My home well is doing some weird stuff. First of all, I have 25 amp breakers going to my 1.5 HP pump that is 160 feet down. In the last few days, it has tripped the breakers 5 times

I ohm'ed out the motor and it is open (infinite resistance) to ground both legs and 3.2 ohms between the 2 leads going to the motor.

The symptoms that I am seeing is that it it taking my well about 7 to 10 minutes to fill up ( I have a 120 gallon galvanized tank with no bladder). When the water pressure in the tank gets to about 30 psi, the water in the house starts discharging air and water combined.

I have changed the starter cap. because the pump sounds as if it is working extra hard at start up, but smooth out as the pressure increases. changing the caps did not help.

I was thinking that the caps may be bad and it was pulling too much current at start up and tripping the breakers. I'm not sure if the system is water logged or not. Any ideas? 4/12/2014 Reader Comments on

Procedures for Diagnosing Tripping Pump Circuit Breaker / Blowing Fuse

Tripping breakers on the pump circuit often mean that

The pump is drawing high current or

There is an actual short circuit in the pump wiring

On occasion we also find that the root problem isn't the pump but a damaged pump pressure control switch.

Watch out: a short circuit in pump wiring can be dangerous to people nearby or to anyone touching the pump or its controls, or in the case of a submersible (in-well) pump, a danger to anyone touching the well casing as it may become energized with voltage enough to shock or even kill somoene.

If we don't have a short in the circuit then unfortunately that makes us suspect a failing pump motor

Keep in mind that motor tests are tricky because once parts start spinning an internal winding can move, changing the electrical properties of the device.

From what I've been studying just recently, there are useful relationships between motor current draw and other conditions besides a failing motor.

Illustration at above-left: orange extension cord wiring used to hook up the pump pressure control switch is an improper and unsafe electrical installation.

E.g.

• Abnormally-low pump circuit current draw:
  
  a water pump that is running in a dry well will draw lower than normal current.
• Abnormally-high pump circuit draw:
  
  a pump running against unusual resistance (blocked outlet) may draw higher than normal current, as would a pump with a binding impeller or rotor or a bad bearing. If you could see the pump operating (which you can't under water very easily) you might see an abnormal temperature rise too.
• Abnormal resistance 
  
  on pump circuit wires (with POWER OFF so we don't get fried) an indicate a shorted or grounded wire (zero or abnormally low resistance) or an open circuit (broken wire, high or infinite resistance)

So we could argue that a pump running against a waterlogged pressure tank might see higher than normal pressure but I doubt it. A water logged pressure tank will quickly if not immediately reach cut-out pressure and turn off the pump (unless the pressure control switch is itself faulty and not sensing that the tank is up to pressure).

Anyway it's easy enough to check for a waterlogged tank, as we discuss in this article series.

I think I'd

• Check for loose electrical connections or damaged wire (cut, nicked, worn, shorting) anywhere in the pump and pump control circuit
• Pull the pump and check for binding bearings, (is the pump unusually noisy?), a damaged impeller that's binding,
  
  and if those looked good I would take the entire pump (motor and pump impeller assembly) to an electric motor repair shop for more expert testing, or if you're qualified and trained to do so, check the motor's start and run current draw or amperage against the motor's data tag.

Reader follow-up: successful well pump diagnosis traced to damaged pump wiring between house and well

I've got this thing working. I went to go on vacation the last couple of days but had issues so I had to come home.

Image at left, not from Joe's home, illustrates un-protected 240V wiring entering the well casing at the casing top of a water well located in a building basement.

I spent all day with it, watching it, listening to it. Here is what I found:

I was showing 238V at the cut off box at the control box. When the pump kicked on, I was loosing one leg and this was tripping the double pole breaker.

I tested this theory (I actually seen the leg go off with the meter) by taking my generator and hooking the 230V side up to the pump.

I have a 7000 watt generator, so there was no issue running the pump. It took about 5 minutes to fill the 120 gallon tank.

It took forever [for the water tank pressure] to get past 25 psi, but once it hit 30 psi it took about 2 minutes for it to reach the cut off pressure of 68 psi (my pump and tank are quite a ways from my house and I adjusted the pressure).

I had my wife and kids take showers, run the washing machine, and even used the sprinkler in the yard for a couple of hours and watched the pressure gauge and everything worked as normal.

With that being said, my power wire from the breaker box to the well is buried underground. I dug it up today and found a burned spot in the insulation. I cut the insulation back and found that the leg I was loosing when the pump came on was damaged.

I guess there was a nick in the wire when I buried it and didn't notice it. When the pump was not running, there was no current being pulled even though the voltage was still there.

When current started passing through the wire, there was enough missing insulation to trip the breaker - like a ground fault on a 480V system.

I am an industrial electrician and I'm very familiar with 480V-2300V systems. I wasn't sure in my original post if I was seeing an issue with the air pressure in the tank or something along those lines.

Final fix: repaired bad wire going to the pump control box.

Well Wiring & Pump Diagnostic Procedure Details

See the Well Pump and Wiring Tables given just below.

For readers who are qualified and know how to use electrical test instruments, for safety and completeness also see

• AMPS MEASUREMENT METHODS - checking current draw
• DMM DIGITAL MULTIMETER HOW TO USE - including checking resistance and wiring integrity
• DMMs VOMs SAFE USE OF - to avoid electrocuting yourself or burning down the house
ELECTRIC MOTOR DIAGNOSTIC GUIDE - how to test and diagnose problems with an electric motor or its start/run capacitor
• VOLTS MEASUREMENT METHODS - checking voltage levels

Also see this helpful

• SINGLE PHASE PUMP SERVICE MANUAL [PDF] (2005) Goulds, ITT, Website: www.goulds.com available from the company or free as a download at InspectApedia for examples of resistance tests of well pump motors and wiring.

Pump Wiring & Circuit Diagnosis

Pump Motor Overheats Diagnosis

Pump Runs too Often: Diagnosis

Notes: to the tables above

Some of the well pump troubleshooting suggestions in this list can be found at the Betta-Flo Jet Pump Installation Manual from the National Pump Co. Page top illustration courtesy of Carson Dunlop Associates, a Toronto home inspection, education & report writing tool company [ carsondunlop.com ].

Submersible Pump Wiring Diagrams & Connections

On 2018-08-19 by Greg Rhymer - wiring connections when installing a four-wire submersible well pump

Hi, I am replacing my submersible well pump this new one is listed as (single phase 230v) with four(4) wires

two (2) are hot leads

one (1) is a ground

the last one (1) connects the capacitor motor.

Now is where my confusion begins

I only have three (3) wires at the well head and that continues through out the remainder of my system being the breaker shut off and the pressure switch. would I connect the capacitor to the common?

Since I will already need to connect the two (2) hot leads together.

[Click to enlarge any image]

I have provided a picture of the inside cover of control box diagram.

On 2018-08-19 by (mod) - wiring diagram of a a 4-wire pump circuit

Greg, I'll be glad to research this further as from your question and image I'm not confident I can give a correct answer right-off.

What are the brand and model of the new pump?

What are the brand and model of the old pump?

Do we have a wiring diagram from the original submersible? Or the old control box?

Meanwhile, I have marked the identity of the wires in your wiring diagram.

Typical 3 or 4-wire Submersible Pump Control Box Wiring Diagram

These 4-wire well pump wiring connections are typical for a single-phase submersible pump.

• GREEN = ground
• BLUE = run - this will be one of the two Line In power wires
• BROWN or RED = start wire between motor starting capacitor and motor S terminal as shown above
• BLACK = common - this will be the second of two Line In power wires

In the schematic above the orange wire connects the motor start relay CAP (Capacitor) terminal to the motor's Start/Run capacitor itself.

You will see that

• GREEN or safety ground connects to the circuit ground and typically to a control box ground terminal and a motor chassis ground terminal
• BLUE or "run"wire connects from the On-Off switch or relay to a capacitor R terminal and also to the motor's R or run terminal.
• BROWN or "start" wire connects from the S terminal on the capacitor to the S terminal on the motor
• BLACK or common connects from the on-off switch, often through an overload switch and on to the pump motor's C or common terminal

Notice that in a 3-wire well pump there is no white wire or neutral wire being used in this installation, even if the white neutral is present in your electrical box.

Power flows as follows:

Watch out: I cannot advise you to connect your pump to this control before we know more, as a short circuit could kill you.

? You have not told me if your pump is a 120V or a 240V motor, ditto for the control.

? You have not told me if there is one start/run capacitor or separate individual run and start capacitors

Typical 2-wire 240V Well Pump Wiring Connections

A 2-wire 240V well pump may have the following wires present and connected as given at the control box:

Notice in our two-wire pump wiring installation schematic above that both L1 and L2 "hot" wires may be black in color or one may be black, the other red.

• L1 - Line 1 from power source - black wire
• L2 - Line 2 from power source - black or red wire
• G - Ground from electrical system & ground to well pump circuit - green wire
• M1 - Motor 1 to pump motor - black or red wire
• M2 - Motor 2 to pump motor - black or red wire

Below is an example of wiring a 2-wire 230V Sta-Rite s724 well pump; note that this pump can be switched to run at 115V but is factory-set to 230V.

Details for this well pump are

at STA-RITE SSJ-SERIES VERTICAL JET PUMP INSTRUCTION MANUAL [PDF] S724-series jet pumps (2013, revised 2015)

Typical 3-wire 240V Well Pump Wiring Connections

[Click to enlarge any image]

A 3-wire pump control box may actually have 6 physical wires present as follows:

Inputs:

• Line 1 - L1 - power in from pressure control switch, possibly through an overload or pump protection switch
• Line 2 - L2 - power in from pressure control switch, also possibly through an overload or pump protection switch

Outputs

• Red - pump run
• Black - pump common
• Yellow (or blue) pump start circuit
• Green - ground - earth

Above: Example wiring details using the Franklin Electric Pumptec-Plus pump controller - citation and manual links provided below. [Click to enlarge any image]

Watch out: your pump wiring requirements may differ: consult the IO manual for your pump and pump controller.

Well Pump Wiring Size vs Distance & Voltage

Check also that your well pump wiring has been properly sized for the distance from building to well pump (e.g. for a submersible pump in the well). This table is a general guideline for well pump wiring sizing.

Notes to the table above:

• Wire notes: copper wire only
• Source: JET PUMP FAQs [PDF] Home Depot Stores, retrieved 2020/02/18 original source: https://images.homedepot-static.com/catalog/pdfImages/de/de8304aa-64d4-47ec-b075-a0e25c0ff64a.pdf
• See also WATER PUMP CAPACITIES TYPES RATES GPM
• See also DEEP WELL PUMP WIRE SIZE TABLE [PDF] Tuhorse, retrieved 2021/11/25 original source: https://www.tuhorse.us/drop-wire-selection-and-combining/
• For longer pump wire runs see SE CABLE & WIRE SIZES FOR LONG RUNS
• Watch out: the engineering work and derivation of the table above is derived from the sources listed below including manufacturer's tables and online voltage drop calculators but may not be correct for your specific installation. Check with your engineer or electrician.

Well Pump Wiring Guides, Manuals References

Illustration: Franklin Electric provides this Pumptec Control Box # 5800020610 that includes a pump protection circuit that prevents the pump from running dry: particularly suitable for low-yield wells. The control will stop the pump in low water conditions.

• Franklin Electric, 4" ENVIRONMENTAL E-SERIES PUMPS OWNERS MANUAL [PDF] Franklin Electric, 400 E. Spring St., Bluffton, IN 46714 USA Tel: 260-824-2900 Web: https://franklinwater.com/ retrieved 2021/06/25, original source: https://franklinwater.com/media/110586/106259101_E_Series_06-12_WEB.pdf
• Franklin Electric, PUMPTEC CONTROL BOX & PUMP PROTECTION DEVICE IO MANUAL [PDF] Franklin Electric, 400 E. Spring St., Bluffton, IN 46714 USA Tel: 260-824-2900 Web: www.franklin-electric.com
• Franklin Electric, PUMPTEC-PLUS PUMP CONTROL & PROTECTION SYSTEM INSTALLATION GUIDE [PDF] Franklin Electric, op. cit.,
• Franklin Electric PUMPTEC QD CONTROL BOX INSTALLATION MANUAL [PDF] Franklin Electric, op. cit., retrieved 2021/06/25, original source: https://franklinwater.com/media/180820/qd_pumptec_manual-225559101_m1551-.pdf
  
  Excerpt: The QD Pumptec protects submersible pumping systems and is designed speci cally for use with Franklin Electric’s QD Relay Control Boxes and Franklin 230 V three-wire motors. The QD Pumptec microcontroller continuously monitors line voltage and motor current to protect against over voltage, under voltage and dry well conditions.
  
  Dry well conditions are detected when the motor load drops below a factory preset (or  eld calibrated) level for more than three seconds. When a dry well condition is detected, the unit will automatically restart after a selectable timeout period ranging from 2 to 240 minutes. Under and over voltage conditions will shut the unit off for two minutes and then automatically restart.
  
  The QD Pumptec allows the user to choose the standard factory calibration for underload or to calibrate to a particular system. The user may select a reset time between 2 and 240 minutes. Note: Although the QD Pumptec may detect a deadhead condition, it is not guaranteed. Not all pumps unload under deadhead conditions.
• Pumptrol® PRESSURE SWITCH ADJUSTMENT, [PDF] Square D, Schneider Electric Corporation, 8001 Knightdale Blvd., Knightdale< NC 27545 1-888-778-2733 - Square D Technical Library, web search 07/24/2010 original source: http://ecatalog.squared.com/techlib/docdetail.cfm?oid=09008926800a93be
• 9013 Pumptrol® COMMERCIAL PRESSURE SWITCHES Type F and 9013 Commercial Pressure Switches Type G, Catalog, [PDF] SquareD, Schneider Electric Industries SAS, Schneider Electric Industries SAS, web search 02/23/2011, original source: http://ecatalog.squared.com/pubs/Machine Control/ Pressure-Float-Vacuum Switches/Pressure Switches-Water and Air/9013CT9701.pdf
  
• Class 9013 Square D Commercial Pressure Switches: WATER PUMP PRESSURE CONTROL SWITCH CLASS 9013, Type F, G, Manual, [PDF] Square D Company, 8001 Highway 64 East, Knightdale, NC 27545-9023, USA, (919) 266-3671, www.squared.com, web search 02/24/2011, original source: stevenengineering.com/tech_support/PDFs/45COM.pdf. Quoting:
  
  The Type FSG, FYG, FRG - PUMPTROL® Water Pump Pressure Switches are used to control Water Pump Pressure Switches are used to control
  electrically driven water pumps and have the following features:
  • The Type FSG is the standard water pump switch, suitable for all types of pumps: jets, submersible,
    reciprocating, etc.
  • The Type FYG is designed to meet higher horsepower and pressure requirements.
  • The Type FRG is reverse acting: the contacts open on falling pressure.
    All are diaphragm actuated.
  • The Type G - PUMPTROL® Commercial/Light Industrial Pressure Switch is used to control electrically driven water pumps and air compressors.
    
    It has higher electrical ratings for direct control of motors in pump and compressor applications. The Type G switch is diaphragm actuated and has contacts that open on rising pressure.
• Water Pumps Direct HOW to INSTALL and WIRE a WeLL PUMP - Welll Pump Installation Guide [PDF] by Jim O. "Water Pump Expert" at this page, Water Pumps Direct, Tel: 888-455-4681, Web: waterpumpsdirect.com - retrieved 2023/09/14, original source: waterpumpsdirect.com/stories/1852-Well-Pump-Installation-Guide.html

Causes Of & Cures For Broken Submersible Well pump Wiring

This discussion has moved to WATER PUMP WIRING DAMAGE