A water bore pump that hums, clicks, trips the circuit breaker, struggles to start or suddenly stops working does not automatically need a new submersible pump.
Bore pump capacitor Perth
Sometimes the problem is an electrical component such as a bore pump capacitor.
Capacitors are used in many single-phase bore pump motors and control systems. They play an important role in starting the motor and, depending on the motor design, may also remain in circuit while the pump is running.
However, a failed capacitor can also be the result of another problem rather than the original cause.
That is why proper bore pump fault diagnosis is important before replacing expensive equipment.
At Aquarian Drilling, we diagnose complete bore systems throughout Perth, including submersible pumps, centrifugal pumps, motors, capacitors, starters, control boxes, electrical cabling, reticulation controls and the bore itself.
What Does a Bore Pump Capacitor Do?
Most Perth homes have a single-phase electrical supply.
A single-phase induction motor needs assistance to create the rotating magnetic field and starting torque required to get the motor moving.
A capacitor works with an auxiliary motor winding to create an electrical phase shift.
In simple terms:
The capacitor helps the bore pump motor start and, on some motor designs, helps it continue operating correctly.
The exact arrangement depends on the motor.
Some pumps use a start capacitor.
Others use a run capacitor.
Some use both.
Some have the capacitor inside an external control box.
Two wire pumps use starting components built into the motor.
Three-phase motors operate differently again.
This is why there is no universal capacitor that fits every bore pump.
Although both are capacitors, a start capacitor and run capacitor perform different functions.
Start Capacitor
A start capacitor helps produce high starting torque when the motor is first energised.
Start Capacitor vs Run Capacitor
Starting a submerged pump can require considerably more torque than keeping it running.
Once the motor reaches the appropriate speed, the start capacitor is normally disconnected from the starting circuit by a relay or other starting device.
A faulty start capacitor may cause symptoms including:
Pump humming but not starting
Pump trying to start and immediately stopping
Starter clicking
Motor overload operating
Circuit breaker tripping
Slow starting
Intermittent starting
Pump starting on some occasions but not others
Run Capacitor
A run capacitor remains connected while the motor operates.
It helps maintain the required phase relationship between the motor windings.
A weak, failed or incorrectly sized run capacitor can contribute to:
Poor motor performance
Higher motor current
Overheating
Reduced efficiency
Overload operation
Unusual motor noise
Difficulty starting
Premature motor deterioration
PSC, CSIR and CSCR Bore Motors
Different single-phase bore motors use different starting arrangements.
Understanding the difference helps explain why one bore may have only one capacitor while another control box contains two.
PSC – Permanent Split Capacitor
A Permanent Split Capacitor motor uses a run-type capacitor that remains connected during operation.
The capacitor assists both starting and running.
CSIR – Capacitor Start, Induction Run
A CSIR motor uses a start capacitor to provide additional starting torque.
Once the motor starts, the capacitor is disconnected and the motor continues running without it.
CSCR – Capacitor Start, Capacitor Run
A CSCR motor uses both a start capacitor and a run capacitor.
The start capacitor assists during acceleration.
The run capacitor remains connected while the motor operates.
The motor type must therefore be identified before replacing electrical components.
Lowara Bore Pump Capacitors
Lowara submersible pumps and motors are commonly found in Perth water bore installations.
Aquarian Drilling services and diagnoses Lowara bore pumps, including electrical, motor, control box and pump faults.
Lowara single-phase submersible motor installations can use a suitable electrical control panel containing motor overload protection and a capacitor.
The capacitor must be matched to the motor.
It should not be selected simply because another capacitor has the same physical dimensions or terminal arrangement.
Lowara 4OS Single-Phase Motors
Lowara’s 4OS submersible motor documentation specifies that applicable single-phase motors should be connected through a suitable control panel containing overload protection and the capacitor.
The required capacitor capacity should be identified from the motor information and manufacturer’s specifications.
Depending on the motor size, capacitor requirements differ substantially.
This is important because fitting an incorrectly rated capacitor can cause poor starting, abnormal current or further equipment damage.
Where Is the Capacitor on a Lowara Bore Pump?
On applicable Lowara single-phase installations, the capacitor may be located inside an above-ground electrical control panel.
Depending on the system, the box may also contain:
Motor overload protection
Relay or contactor
Electrical terminals
Control circuitry
Reticulation interface
Switching equipment
The ability to access these components above ground is useful during diagnosis.
If an external capacitor, relay or control component has failed, it may be possible to repair the system without immediately removing the submersible pump from the bore.
Does Every Lowara Bore Pump Have a Capacitor?
No.
The answer depends on the motor and electrical configuration.
Single-phase and three-phase systems operate differently, and different motor designs use different starting arrangements.
The pump model alone does not necessarily tell you what electrical system is installed.
The motor, supply phase and control equipment also need to be identified.
Grundfos Bore Pump Capacitors
Grundfos manufactures several different types of submersible motors and pump systems.
Some Grundfos single-phase motors use capacitors, but it is incorrect to assume that every Grundfos bore pump uses a conventional external start capacitor.
Grundfos documentation describes several arrangements including Permanent Split Capacitor motors and three-wire capacitor-start systems.
Grundfos PSC Motors
Applicable Grundfos PSC motors use a run capacitor that remains connected during operation.
The capacitor must be correctly sized for the motor.
Grundfos Three-Wire Motors
Some three-wire single-phase submersible motor systems require an external control box containing capacitors and switching components.
Depending on the design, the box can contain:
Start capacitor
Run capacitor
Starting relay
Contactor
Motor protection
Grundfos SQ Pumps Are Different
The Grundfos SQ range should not be treated like a conventional external capacitor-start bore pump.
SQ motors incorporate electronic motor control and protection.
Therefore, finding a Grundfos bore pump on a property does not automatically mean there will be a replaceable capacitor in an external control box.
Correct pump and motor identification is essential.
Franklin Electric Submersible Motor Control Boxes
Franklin produces control boxes specifically for three-wire single-phase submersible motors.
Depending on the control box design, these can use:
Start capacitors
Run capacitors
Relays
Overload protection
Contactors
Franklin’s capacitor-run control boxes incorporate a run capacitor to assist motor operation.
Again, the control box and motor need to be correctly matched.
Davey Bore Pumps and Centrifugal Pumps
Davey pumps are commonly encountered in Australian water systems, particularly in older surface-mounted centrifugal pump installations.
Depending on the pump and motor design, single-phase centrifugal pumps may use a start or run capacitor mounted beneath the motor’s electrical cover.
A failed capacitor can cause symptoms such as:
Motor humming
Pump failing to start
Overload operation
Intermittent starting
Reduced motor performance
However, centrifugal bore pumps have additional potential faults that need to be considered.
These include:
Loss of prime
Suction leaks
Failed foot valve
Blocked suction
Falling water level
Pump wear
Mechanical seizure
A humming Davey pump does not automatically mean the capacitor is the only problem.
Calpeda Bore Pumps
Calpeda submersible pumps are also used in bore applications.
As with other brands, the capacitor arrangement depends primarily on the motor and electrical system rather than the pump name alone.
Single-phase motor systems may use capacitor-based starting arrangements, while three-phase systems do not use a conventional single-phase start capacitor.
When diagnosing a Calpeda bore pump, the motor, electrical supply and control arrangement should be identified before replacing components.
Onga, Ebara, Sumoto and Other Bore Pump Motors
Perth water bores contain many different pump and motor combinations.
Other brands encountered can include:
Onga
Ebara
Sumoto
Red Jacket
Stalker
Older discontinued pumps
Mixed pump-and-motor combinations
In many installations, the pump hydraulic end and electric motor may even be different brands.
That is particularly important with submersible pumps.
The name on the pump does not always identify the motor or tell you what type of starting equipment it requires.
Why Do Bore Pump Capacitors Fail?
Capacitors are electrical components and have a finite service life.
However, they can also fail prematurely because of problems elsewhere in the system.
When we find a failed capacitor, the important question is not only:
“Is the capacitor faulty?”
It is also:
“Why did it fail?”
1. Age
Capacitors deteriorate over time.
Their internal electrical characteristics can gradually change until the capacitance falls outside the acceptable range.
A capacitor may therefore be faulty even if there is no obvious visible damage.
2. Heat
Heat accelerates deterioration in electrical components.
Bore pump control boxes are often installed outside.
A box exposed to Perth summer sun can become considerably hotter than the surrounding air.
Repeated exposure to high temperatures can shorten the life of capacitors, relays and other electrical components.
3. Excessive Starting and Pump Cycling
Motor starting creates greater electrical stress than normal running.
A pump that starts and stops excessively can therefore experience accelerated component wear.
Frequent cycling can be caused by:
Waterlogged pressure tank
Incorrect pressure vessel pre-charge
Faulty pressure switch
Leaking pipework
Leaking non-return valve
Small irrigation stations
Incorrect reticulation design
Faulty solenoid valves
Poor controller setup
Automatic control faults
Replacing the capacitor without fixing the cycling problem may result in another failure.
4. Low Voltage
Electric motors are designed to operate within specified voltage limits.
Low voltage can make starting more difficult and can increase motor current.
Possible causes include:
Long cable runs
Undersized cable
Loose electrical connections
Corroded terminals
Damaged cable
Poor joints
Supply problems
Incorrect generator supply
Voltage should therefore be checked under appropriate operating conditions.
5. Voltage Surges
Power disturbances can damage electrical components.
Possible causes include:
Lightning
Network disturbances
Switching surges
Generator issues
Electrical faults
Loose connections
A damaged capacitor may be only one part of the resulting fault.
6. Incorrect Capacitor
Capacitors are rated by capacitance, normally measured in microfarads or µF, as well as voltage and other specifications.
A replacement capacitor needs to suit the motor and control system.
Installing a capacitor because it physically fits is not sufficient.
7. Faulty Starting Relay
In some systems, a relay connects and disconnects the start capacitor.
If the relay fails to remove the capacitor correctly after the motor starts, the capacitor can overheat and fail.
Therefore, a burnt capacitor may be the damaged component rather than the original cause of the failure.
8. Mechanical Pump Problems
Sometimes an apparent electrical fault originates down the bore.
A pump can become difficult to start because of:
Sand
Silt
Iron deposits
Mineral deposits
Damaged impellers
Bearing problems
Foreign material
Mechanical seizure
A mechanically overloaded pump can place additional strain on the motor and starting components.
9. Water and Corrosion
Bore control equipment frequently operates in harsh conditions.
Possible problems include:
Rainwater
Reticulation spray
Condensation
Corrosion
Insects
Poor cable entries
Damaged seals
Coastal conditions
Water inside a control box can damage far more than the capacitor.
10. Loose or Burnt Electrical Connections
A poor electrical connection can create heat, voltage drop and intermittent operation.
Signs may include:
Darkened terminals
Melted insulation
Burnt connectors
Loose screws
Corrosion
Discoloured wiring
Simply replacing a capacitor without correcting poor connections may not solve the problem.
What Does a Failed Bore Pump Capacitor Look Like?
Some failures are obvious.
A damaged capacitor may appear:
Bulged
Swollen
Split
Leaking
Burnt
Discoloured
Melted around the terminals
However, visual inspection alone is not enough.
A capacitor can look completely normal and still be electrically faulty.
Capacitance needs to be properly tested.
Common Symptoms of a Bore Pump Capacitor Fault
Customers commonly describe capacitor-related bore faults as:
“My bore pump is humming.”
“The reticulation starts but no water comes out.”
“The bore keeps tripping the breaker.”
“The pump clicks but won’t start.”
“It works sometimes and not others.”
“The pump starts and then cuts out.”
“The control box is buzzing.”
“The bore suddenly stopped working.”
These symptoms can indicate a capacitor problem.
But they can also be caused by other faults.
Bore Pump Hums but Won’t Start
A humming pump usually tells us that electricity is reaching at least part of the system.
Possible causes can include:
Failed capacitor
Low voltage
Faulty relay
Motor winding problem
Damaged cable
Mechanical pump seizure
Locked rotor
Poor electrical connection
This is why replacing a capacitor without testing can be misleading.
Bore Pump Trips the Circuit Breaker
A bore circuit breaker tripping can be caused by:
Shorted capacitor
Motor winding fault
Damaged cable
Water ingress
Insulation breakdown
Locked pump
Electrical connection fault
Control equipment failure
A circuit breaker trip does not automatically mean the submersible pump has burnt out.
Pump Starts Intermittently
An intermittent fault can be particularly frustrating.
The pump may run normally one day and refuse to start the next.
Possible causes include:
Weak capacitor
Faulty relay
Loose connection
Pressure switch problem
Contactor fault
Supply voltage problem
Motor fault
Cable fault
Testing should attempt to identify the actual cause rather than guessing.
Capacitor Keeps Failing
If a capacitor is replaced and then fails again within a relatively short period, repeatedly fitting another capacitor is unlikely to be the best solution.
The system should be checked for:
Incorrect capacitor value
High or low voltage
Excessive cycling
Faulty starting relay
Mechanical pump load
Poor electrical connections
Excessive heat
Motor problems
Control system faults
Repeated capacitor failure is often evidence that something else requires attention.
Pump Runs but No Water Comes Out
If the motor is genuinely running but no water is being delivered, the fault is less likely to be a simple starting capacitor.
Possible causes include:
Falling groundwater level
Damaged rising main
Blocked pump
Worn impellers
Failed non-return valve
Loss of prime
Suction leak
Failed foot valve
Bore deterioration
Pump running backwards on a three-phase installation
This is an important diagnostic distinction.
Don’t Assume the Bore Has Run Dry
A bore that suddenly stops producing water is not necessarily dry.
The fault could be:
Electrical supply
Capacitor
Relay
Contactor
Controller
Motor overload
Electrical cable
Submersible motor
Pump
Rising main
Non-return valve
Reticulation system
Water level
Bore condition
A proper diagnosis separates electrical, mechanical, hydraulic and groundwater faults.
How Is a Bore Pump Capacitor Tested?
Capacitor testing requires appropriate electrical test equipment.
The actual capacitance can be measured and compared against the specified µF rating and acceptable tolerance.
However, capacitor testing should normally form part of a wider bore pump diagnosis.
Depending on the fault, testing may include:
Supply voltage
Voltage under load
Capacitance
Motor current
Starting current
Motor winding resistance
Insulation resistance
Earth leakage
Control box components
Starting relay
Contactor
Motor protection
Cable condition
Pressure controls
Reticulation control signal
Pump performance
Bore performance
Why Insulation Resistance Testing Matters
A submersible motor operates underwater.
Its electrical cable can also run tens of metres down the bore.
Damage or deterioration of either the motor windings or down-hole cable can cause:
Circuit breaker tripping
Earth leakage
Intermittent faults
Poor starting
Complete motor failure
Insulation resistance testing can help determine whether the problem is in the motor, cable or another component.
Is It the Capacitor, Motor, Pump or Bore?
A useful starting guide is:
Pump hums but won’t start
Investigate the capacitor, starting circuit, supply voltage, motor and mechanical pump condition.
Pump immediately trips protection
Investigate the capacitor, motor, electrical cable, insulation and control equipment.
Pump runs but produces no water
Investigate the pump hydraulics, rising main, groundwater level, non-return valve and bore.
Pump starts and stops repeatedly
Investigate the controls, pressure system, water supply and reticulation demand.
Pump gradually loses pressure
Investigate pump wear, groundwater level, bore condition and reticulation demand.
Pump is completely dead
Investigate power supply, controller, starter, overload, electrical cable and motor.
Should You Replace the Bore Pump Because the Capacitor Has Failed?
Not necessarily.
If the fault is limited to an accessible capacitor, relay or control component, the pump and motor may still be serviceable.
This is particularly important with submersible pumps.
A pump may be installed 20, 30, 40, 50 metres or more below ground.
Removing it is considerably more involved than testing accessible electrical components.
Where practical, it makes sense to establish whether the problem is above ground before deciding that the pump needs to be removed.
Can You Replace a Bore Pump Capacitor Yourself?
Bore pump capacitors form part of mains-voltage electrical equipment.
Capacitors can also retain an electrical charge after the power supply has been isolated.
Electrical diagnosis and repairs should therefore be undertaken by appropriately qualified people.
There is also a practical reason not to simply replace the component yourself.
A failed capacitor may be the symptom of another problem.
Replacing it without identifying the cause may result in another failure or leave a more serious motor or pump fault undetected.
Bore Pump Capacitor Repairs Perth
Aquarian Drilling provides water bore fault diagnosis and repairs throughout Perth and surrounding areas.
Our experience covers the complete bore system rather than treating the capacitor as an isolated component.
Depending on the installation, we can investigate:
Bore pump capacitors
Lowara bore pumps
Grundfos bore pumps
Calpeda bore pumps
Davey pumps
Franklin motor systems
Submersible pump starters
Control boxes
Motor faults
Electrical cabling
Pump overloads
Contactors and relays
Pressure controls
Reticulation controls
Submersible pumps
Surface centrifugal pumps
Old concrete wells
Low-flowing bores
Bore performance problems
Frequently Asked Questions About Bore Pump Capacitors
Does a Lowara bore pump have a capacitor?
Many applicable single-phase Lowara submersible motor installations use a capacitor as part of their electrical control arrangement.
However, the exact configuration depends on the motor and control system.
Three-phase motors use a different electrical arrangement.
Where is the capacitor on a Lowara bore pump?
On applicable single-phase installations, the capacitor may be located inside an above-ground electrical control panel.
The motor and control equipment should be identified before assuming where the capacitor is located.
What size capacitor does a Lowara pump need?
There is no universal Lowara capacitor size.
The required value depends on the motor.
The correct capacitor should be confirmed from the motor identification and manufacturer specifications.
Does a Grundfos bore pump have a capacitor?
Some Grundfos single-phase motor systems use capacitors, including PSC and certain three-wire configurations.
Other Grundfos systems, including electronically controlled pump ranges, operate differently.
Does a Franklin submersible motor use a capacitor?
Franklin three-wire single-phase submersible motor systems can use external control boxes containing start and, in some configurations, run capacitors.
The control box must be correctly matched to the motor.
Can a faulty capacitor trip the circuit breaker?
Yes.
Certain capacitor faults can cause or contribute to electrical protection operating.
However, motor, cable, insulation and control faults can produce the same symptom.
Why does my bore pump just hum?
A failed or weak capacitor is one possibility.
Other causes include low voltage, a faulty starting circuit, damaged motor, cable fault or mechanically seized pump.
Can a capacitor look normal and still be faulty?
Yes.
Capacitors can deteriorate electrically without swelling, leaking or showing visible damage.
Can a bad capacitor damage a bore pump motor?
An incorrect or malfunctioning starting system can place abnormal stress on the motor.
The underlying fault should therefore be investigated rather than repeatedly replacing capacitors.
My bore pump is running but there is no water. Is it the capacitor?
If the motor is genuinely running normally, a starting capacitor becomes a less likely explanation.
The problem may instead involve the pump, rising main, water level, bore condition or suction system.
Does a failed capacitor mean I need a new bore pump?
No.
The capacitor is a separate component.
A failed accessible capacitor may sometimes be repaired without replacing the submersible pump.
Testing is required to establish whether the motor and pump remain serviceable.
Why does my bore pump capacitor keep blowing?
Repeated failures can indicate excessive cycling, incorrect capacitor selection, abnormal voltage, heat, a faulty relay, electrical connection problems or excessive motor load.
Bore Pump Won’t Start? Diagnose the Fault Before Replacing the Pump
When a Perth water bore stops working, replacing the complete pump should not automatically be the first step.
Sometimes the fault is a capacitor.
It can also be a relay, controller, cable or electrical connection.
Sometimes the motor or pump has failed.
And sometimes the electrical system is working correctly and the problem is actually within the bore.
Aquarian Drilling combines water bore experience, pump diagnosis and specialist electrical knowledge to identify what has actually failed before recommending major replacement work.
If your bore pump is humming, tripping the circuit breaker, starting intermittently, losing pressure or has stopped pumping water, contact Aquarian Drilling for an assessment.
Aquarian Drilling – Perth Water Bore Drilling, Pump Repairs and Bore Diagnostics
For professional fault finding and repairs, see our Bore Repairs Perth service.
Phone: 0417 928 330
Email: perthbores@iinet.net.au