Unusual high or low voltages and a lost power feed are reasons why a well pump doesn’t work after a power outage.
A power outage by itself won’t damage a well pump. Instead it’s the fluctuating voltages which are common before an outage that will cause problems to the components in a pump.
If the property is on two or three phase power then it is possible that the phase the well is on is still offline. This means that waiting for that particular phase to come back online should resolve the problem. This post aims to cover these three reasons why the well pump isn’t working and what you can do about it from an electrician’s perspective.
Well Pump Wiring & Fault Finding
A well pump typically contains a single phase motor (larger pumps might be two or three phase). The way to tell is to check the plug (if it has one and isn’t hardwired).
A single phase motor will have a standard three pin plug while a three phase motor will have a plug with four or five pins.
If the well pump is single phase it will have capacitors which help it run.
There may be a flow controller which contains electronics.
There may be a motor starter used to start and stop the pump There may also be several control circuits containing things like pressure switches and float switches. It all depends on how complicated the well pump setup is.
It is worth mentioning these because these could be susceptible to damage if there are fluctuating voltages due to an outage.
The well pump will be fed from the switchboard. There will hopefully be fuses for the well pump that will protect the motor and circuit from short circuits and overloads. These fuses do not protect the well pump from surges unfortunately.
With this basic knowledge about how a well pump works electrically lets see how the events before a power outage can cause it to stop working.
Well Pump Not Working After Power Outage? – Reason #1
High Voltage Fluctuation
Likelihood: High – fluctuating high voltages preceding a power outage are a common reason why appliances and motors containing capacitors and other electronics fail in my experience. Contact your lines company for more information on what has caused the fault.
Fixable? Electronic components will likely be damaged and need replacing.
Best case is that you just need to turn the motor fan with a screwdriver to get the motor to work again.
Next best case is that you need to replace the capacitor.
Worst case is that you need to replace the entire motor and any associated control circuits damaged by fluctuating voltages.
A motor is designed to work at a specific voltage. This varies between countries. For example in the USA the voltage is 110 volts single phase but in AUS/UK/NZ is 230 volts phase. When the voltage increases it causes problems for the motor especially with the motor windings and any capacitors.
Capacitors help add torque for single phase motors.
These capacitors are designed to work within a very specific voltage limit and when this is exceeded they short out (often spectacularly) and fail.
A sign of a failed capacitor for a well pump motor is a humming sound with the motor failing to move. There may also be burnt areas around the capacitor and even a weird metallic smell.
A high voltage can cause the windings inside the motor to short out and fail. If this has happened it might not be economical to get the motor rewound. Usually it is cheaper to just replace the motor.
High voltage can also destroy electronic components found in a pump flow controller, if one is installed.
High voltage will also damage the windings in three phase motors.
Well Pump Not Working After Power Outage? – Reason #2
Low Voltage Fluctuation
Likelihood: Moderate – Low voltages before an outage will cause the motor in a well pump to burn out. Contact your lines company for more information on what has caused the fault.
Fixable? Possible. Check the switchboard for a tripped breaker. Check the motor for a tripped overload switch located on the body of the motor. Resetting both of these might get the well pump going. It is also possible that the windings are burnt out.
Getting the windings inside the motor of the well pump rewound is unlikely to be economical. Replacement is usually cheaper in this case.
Unusually low voltages are also possible outcomes from a power outage.
If the voltage is low and the pump has been running during this time then it is possible to burn the motor out. This is because the motor draws more current to compensate for the low voltage.
Usually there are protection measures in place to stop the motor from burning out.
Check for an overload switch (or button) on the motor’s body and reset it.
If you have a motor starter, the overload there may need to be reset by pressing the button.
Check for a tripped breaker in the switchboard and reset it. Any of these could get the well pump going.
Otherwise it is likely that the windings inside the motor have burnt out. In this case you will either need to get the windings rewound or buy a new motor.
Well Pump Not Working After Power Outage? – Reason #3
Lost Phase
Likelihood: High – If you are on three phase power. Contact your lines company for more information on what has caused the fault.
Fixable? Just wait for the electrical feed to come back online. That could fix the problem.
If you are on three phase power, there may be a phase which is still offline for some reason (talk to your lines company). Basically, the phase which is still offline powers the well pump. Waiting for it to come back online should resolve the problem.
Get A Surge Protector
A surge protector will protect your pump from high voltage surges associated with power outages. It does this by diverting the voltages away from the well pump to the earthing system thereby protecting the pump. This is especially a good investment if you have electronic devices like flow controllers on the circuit.
Ensuring that the pump has good overload protection is a good idea. This can be located in several places such as in the motor itself, in the motor starter and at the switchboard.
Electricians Perspective
Fluctuating high voltages are the most likely reason why the well pump isn’t working after an outage in my experience.
It is worth checking for any tripped circuit breakers, tripped overloads at the motor starter and tripped overload switches on the pump itself.
Resetting any of these could get the motor going. A blown capacitor can be replaced.
Signs of this include a swollen looking capacitor and weird smells coming from it.
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