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Collapsing building © Daniel FriedmanWater Pump Wiring Troubleshooting & Repair
Well pump wiring diagrams, 3-wire, 4-wire, Install or detect & fix well pump control box & wiring for 2-wire, 3-wire & 4-wire pump installations

  • POST a QUESTION or COMMENT about checking electrical wiring to diagnose well pump problems such as tripping breakers, blown fuses, weak pump performance or no water delivery from a well water pump

Well pump wiring diagnosis & repair:

This article describes troubleshooting a submersible well pump that was causing tripped circuit breakers and that pumped water only at a slow, reduced rate and pressure, and includes well pump wiring diagrams and instructions.

Ultimately using some simple electrical tests the homeowner traced the water pump problems to a nicked well pump wiring circuit wire.

InspectAPedia tolerates no conflicts of interest. We have no relationship with advertisers, products, or services discussed at this website.

Electrical Wiring Damage Causing Water Pump Malfunctions: breaker or fuse trip/blow, poor or weak pump performance

Submersible well pump wiring resistance check procedure at InspectApedia.com adapted from ITT Goulds Pump Service Manual cited in detail in this article. Here we explain how to check voltage, current, resistance to help diagnose well pump problems such as tripping breakers, blown fuses, weak pump performance or no water delivery from a well water pump.

Further below on this page we include wiring diagrams for 115/230V well pumps with diagrams for 2-wire pumps, 3-wire pumps, and 4-wire well or water pump installations.

How to install & wire a pump control box.

[Click to enlarge any image]

Watch out: electrical wiring is dangerous: you could be shocked or killed. If you are not trained and familiar with proper, safe electrical wiring practices don't try it;

On 2018-12-26 by (mod) - how to test a submersible well pump wiring and motor - typical resistance values

This sounds to me as if the 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)

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.

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.

Well pump wiring waterproof electrical splice kit sold at Home Depot stores and other suppliers - discussed at InspectApedia.com

\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.

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.

Goulds Pumps, an ITT company, offers an excellent submersible well pump diagnostic and service manual.

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

On 2018-12-26 by Anonymous - the 20amp pump circuit breaker keeps being thrown

Well pump controls & wiring in state of disrepair (C) Daniel FriedmanI 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.

4/12/2014 Reader Comments on diagnosing weird well pump behavior:

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.

[Click to enlarge any image]

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?

Reply: Tripping breakers on the pump circuit

Joe, Tripping breakers on the pump circuit often mean that the pump is drawing high current [or that there is an actual short circuit].

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.

Water pump wiring defects (C) Daniel FriedmanIf it might help you, take a look at our electric motor diagnostics at

ELECTRIC MOTOR DIAGNOSTIC GUIDE

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

I'm speaking beyond my competence but 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.

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 pull the pump and check for binding bearings, damaged impeller that's binding, and if those looked good I might take it to an electric motor repair shop for more expert testing.

Also see 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.

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.

Well Pump Wire Size vs Distance (typical)

Distance to Pump

Pump

Amps

Typical Wire Size (AWG)
120VAC 220VAC
up to 50 ft / 15m 20A 12 14
50 - 100 ft / 15 - 30m 12 14
100 - 150 ft / 30 - 45m 10 12
150-200 ft / 45 - 60m 8 12
200- 300 ft / 60 - 90m 6 10
2,500 ft / 760m 15A 400 kcmil 3/0

Notes to the table above:

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

Submersible well pump wiring entering at the well casing top - an indoor well (C) Daniel FriedmanI'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 Pump Wiring & Electrical Circuit Diagnostic Table

Pump Trouble Cause

Pump Won't Start

Diagnostic Procedure Repair Procedure
Blown fuse, tripped breaker Replace fuse or breaker - does the pump run and keep running normally?

Be sure proper breaker or fuse size in ampacity is installed

If breakers keep tripping test for shorted pump motor or pump wiring.

Low voltage to the pump Check with VOM at the pressure control switch or at the pump wiring

Be sure the proper size of wire is used for the ampacity and length of circuit;

Test for low voltage to the building.

Loose or broken pump wire

Check wiring against the pump installation manual diagram, check all connections for tightness, shorts, burns, damage

A loose wire can cause intermittent pump or other electrical device failures as well as a hard failure that means no power or blown fuses.

Rewire or repair or replace wiring

See pump wiring tests in this article

See WATER PUMP WIRING DAMAGE

Burned out pump motor Check that the pump pressure control switch is trying to turn on the pump and that there is voltage at the pump wiring Repair or replace the pump motor
Bad pump pressure control switch Check the switch contacts for burning or wear

Adjust or replace the pressure control switch.

Temporary emergency repair by cleaning the switch contacts may be possible.

Bad pump pressure control switch Check the tubing connecting the pressure switch to the pump housing for clogging

Clean or replace the tubing and be sure the connections are not leaky

- an air leak will prevent the switch from sensing pressure properly

Bad pump impeller or impeller seal leak Turn off electric power to pump, see if you can move the impeller or motor - if it won't turn it is jammed or damaged

A bad impeller can jam the pump, causing it to draw high current.

Remove obstruction in impeller housing, inspect for and replace damaged impeller or frozen motor.

Bad pump motor starting capacitor

Use a VOM in ohms setting to check resistance across the capacitor. If the meter does not move (no current flows) the capacitor is "open".

If there is zero resistance the capacitor is shorted.

Replace the starting capacitor
Pump motor shorted out, jammed, burned up Fuse blows or breaker trips as soon as the pump tries to turn on. If the external wiring is ok (no short circuits) the motor is shorted internally Replace the pump motor

...

Things to Check if the Pump Motor Starts but Overheats and Trips its Reset Button

See ELECTRIC MOTOR OVERLOAD RESET SWITCH for how to find and reset this button
Bad line voltage Use a VOM to check the voltage level at the pressure control switch If voltage is too low, check voltage at the electrical panel and check that the proper size wiring was used for the ampacity and length of run and that there are no partial shorts or damaged wires or connectors
Incorrect motor wiring Check the actual electrical wiring against the motor wiring diagram or the installation manual for the equipment Reconnect wiring properly
Motor is too hot due to surroundings - inadequate ventilation

Check the air temperature where the motor is located.

If the air temperature is over 100 degF, the pump may be too hot and its thermal overload switch tripping because of the environment, not a pump problem.

Install adequate ventilation, or if needed, shading, or relocate the motor/equipment to a cool location
Pump operates too long at low water pressure If the well recovery rate is too poor and the pump is operating at low water pressure, possibly because a tailpiece is installed to prevent air injection and pump burn up, the pump may be overheating. Install a valve on the water discharge line and reduce water flow to increase water pressure inside the pump itself.

...

What to do if the well pump runs continuously or runs too often

If the Well Pump Motor Runs Too Often If the pump runs too often the cause may be a control problem, water tank problem, piping problem, or a well problem.

See INTERMITTENT CYCLING WATER PUMPS if the pump runs at odd times for no apparent reason.

See WATER PUMP SHORT CYCLING CAUSES if the pump is turning on and off too frequently.

If the Well Pump Motor Keeps Running & Won't Stop If the pump won't turn off the cause may be a damaged pump control, a plumbing or fixture leak, or a well problem.

Watch out: If the pump motor won't shut off you should turn off electrical power to the pump to avoid damaging it, then diagnose the problem.

See WATER PUMP WONT STOP RUNNING

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

Submersible pump control wiring diagram (C) InspectApedia.com Greg RhymerOn 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

Four wire well pump wiring diagram (C) InspectApedia.com

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

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

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

Wiring diagram for 2-wire 240V submersible well pump (C) InspectApedia.com

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.

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 fo wiring a a 2-wire 230V or 115V Sta-Rite well pump (C) Inspectapedia.com

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

Franklin Electric E-series pump wiriing example cited at Inspectapedia.com

[Click to enlarge any image]

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

Inputs:

Outputs

Pumptec Plus wiring illustration from Franlin Electric cited & discussed at InspectApedia.com

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 Guides, Manuals References

FRANKLIN ELECTRIC Pumptec water pump protection 1/3 HP to 1.5 HP 230/115V LOW YIELD WELLS cited & discussed at InspectApedia.comIllustration: 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.

Causes Of & Cures For Broken Submersible Well pump Wiring

This discussion has moved to WATER PUMP WIRING DAMAGE

 




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Reader Comments, Questions & Answers About The Article Above

Below you will find questions and answers previously posted on this page at its page bottom reader comment box.

Reader Q&A - also see RECOMMENDED ARTICLES & FAQs

On 2023-04-20 by InspectApedia Editor - an experienced electrician or one with any sense would have labeled each wire in the panel individually

@SAM,

I wanted to add that if the breakers in your old electrical panel were labeled, then when the new panel was to be installed, an experienced electrician or one with any sense would have labeled each wire in the panel individually so that when the wires were connected to new breakers in the new panel, their connection position and breaker would be known and thus could be labeled on the panel's list of breakers and their use.

On 2023-04-19 by InspectApedia Publisher

@SAM,

If it's a 220VAC pump and you're only 1 of the two legs then yes you can damage the pump. You need to turn it off.

It's a mistake to ruin your pump because you don't know which breaker turns it off.

Simply switch off each breaker or 220V breaker pair one by one until the pump stops.

Then you will know which breaker operates the pump.

On 2023-04-19 by SAM

@InspectApedia Editor ,
He won't tell me why he did it, but as I said he didn't connect the red wire in the panel, he just placed a marret on it. So the darn pump is always showing hot. The breaker even turned off, it shows that it's connected. Pump is not able to work as it doesn't have enough power.

I am asking if this would break the pump. The well guy refused to come out until the panel is labeled and the pump can be turned off at the panel, (I don't blame him)

On 2023-04-19 by InspectApedia Editor - If NO circuit breakers will turn off your pump then something is certainly wrong and unsafe

@SAM,

If NO circuit breakers will turn off your pump then something is certainly wrong and unsafe.

And if the pump never stops, there's risk of damage to the pump motor or impeller.

If you turn off the MAIN breaker the pump should stop. If not then it's getting power from some other source that needs to be found and turned off.

Let me know what you find./see/do

On 2023-04-19 by SAM

Hi we just had a new electrical panel installed. The electrician marretted the red wire off inside the panel for the well pump, he hasn't said why. I couldn't get it to turn off with the any of the breakers, so I messaged him to ask why.

What I would like to know is would this wreck the well pump? Thank you

On 2022-11-08 by InspectApedia (Editor)

@Bestman Yima,

What you describe about which wires are alive at your water pump control is not necessarily a problem. For example a 220 volt pump will have two hot wires feeding the motor.

Watch out: there's live voltage in that control and if you touch something you could be shocked or killed.

If you post a photo of the identification data tag or model number for your water pump control we can be sure to point you to the proper instructions for it.

On 2022-11-08 by Bestman Yima

Am having issue on with my calendar control box. I tried to pump water but it refused to pump when i open the box, i then discover that the current is running in boy negative and positive wire.

calendar control box (C) InspectApedia.com BestmanYima

On 2022-11-04 by Andrew W

@InspectApedia-911

Many thanks for your advice!

On 2022-11-04 by InspectApedia-911 (mod)

@Andrew W,

You measure the run current if you're interested in the current drawn as the pump is running,

You'd measure the start current if you're diagnosing a motor start problem and want to see the current drawn as the motor is starting.

See detailed procedures for measuring amps at

AMPS MEASUREMENT METHODS

On 2022-11-04 by Andrew W

I would like to measure the current on my 3 wire pump , which has a rated current of 6 - 6.5amps, using a clamp meter. Which specific wire(s) on the pump do I measure, ie., the common, the start and/or the run, to get the measurement? Any advice would be most appreciated.

On 2022-09-03 by InspectApedia-911 (mod) - How do I test with multimeter?

@Talltony1959,

In the article above, in the section titled

Well Pump Wiring Guides, Manuals References

you will find live links to these pages that give detailed motor test instructions

DMM DIGITAL MULTIMETER HOW TO USE

ELECTRIC MOTOR DIAGNOSTIC GUIDE - home

ELECTRIC MOTOR TESTS

Watch out: if you're not familiar with safe and proper electrical wiring and testing you could be shocked or killed.

Also take a look at

DMMs VOMs SAFE USE OF

On 2022-09-03 by Talltony1959

2 wire with ground well pump running but low pressure. How do I test with multimeter?

On 2022-07-15 by InspectApedia-911 (mod) - pump runs but delivered insufficient water

@Gondo,

Could your water source have run out?

On 2022-07-14 by Gondo

I just connected my surbmesible pump and run it by solar. The pump runs but delivered insufficient water. After about 30 minutes it stops and the controller shows two possibilities; cable not connected well or impeller is stuck. But the cable is connected well. What may be the cause.

On 2022-07-11 by InspectApedia-911 (mod) - How long does the red start wire operate before switching to the black run wire?

@Dave Lowthorp,

I think you're asking about the start capacitor on a pump motor. The start capacitor is taken out of a circuit usually by centrifugal switch in the pump motor once the pump gets close to its run speed which on a modern motor would probably be 3450 RPM. That's just milliseconds.

On 2022-07-10 by Dave Lowthorp

How long does the red start wire operate before switching to the black run wire? (2 HP, 230V, 1 PHASE Submersible Water Pump at 200')



...

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Or see WELL PUMP WIRING REPAIR FAQs - questions & answers posted originally at this article

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WATER PUMP WIRING REPAIR at InspectApedia.com - online encyclopedia of building & environmental inspection, testing, diagnosis, repair, & problem prevention advice.


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INDEX to RELATED ARTICLES: ARTICLE INDEX to WATER SUPPLY, PUMPS TANKS WELLS

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