Fluctuating high and low voltages, changing frequencies and a lost incoming electrical feed (lost phase) are four reasons why an oven won’t work after a power outage.
A power outage by itself is not damaging to an oven, instead its the unstable conditions on the power network before the outage that tends to cause ovens to stop working. Depending on what is causing the power outage these unstable conditions can include high voltages, low voltages, different frequencies and lost feeds.
All of which will cause an oven to stop working. This post will explain how each of these damages an oven and whether it is worth fixing from an electrician’s point of view.
Oven Wiring & Fault Finding
An oven is typically one of the main consumers of power in the house. Ovens can be powered by one phase (one electrical feed), two phases (two feeds) or even three phases (three feeds). If the oven is powered by multiple phases you will find that the oven part will be powered by one phase while the cook top will be powered by the other phase.
Losing one phase could cause one part of the oven to stop working such as the oven or the cook top.
You will need to look at the wiring diagram for your own oven brand to see how it is wired.
An oven is usually hardwired, but not always, into a connection point behind the oven.
This cable goes to an oven wall switch which isolates power to the oven.
If the oven is two phase the switch will probably isolate both phases.
This cable will go from the switch to the main switchboard where the cable will terminate into a circuit breaker for the oven and potentially another circuit breaker if the oven is on more than one phase.
This circuit breaker will protect the people if a short circuit or overload were to happen on the circuit.
The circuit breaker will be fed by an incoming power supply from outside the property controlled by the lines companies.
This incoming voltage should be 110 volts 60 Hertz AC for the US and 230 volts 50 Hertz AUS/UK/NZ.
A circuit breaker won’t protect an oven from power outage, instead a surge protector is needed which I will talk about a bit later.
Oven Not Working After Power Outage? – Reason #1
High Voltage
Likelihood? High – quite common in our experience.
Fixable? Generally no, as high voltages will damage many components of the oven.
High voltages will destroy several components in an oven. This can include the oven element, thermostat, any relays or contactors, motors (such as for the fan), low voltage circuits (such as the light), and control circuits.
High voltages can cause damage to electronic components such as capacitors which will short out. Capacitors are also found in motors. The windings in relays, contactors and motors will also likely short out with high voltage.
As you can see, if high voltage has run through your oven it is probably beyond being saved.
In this case it might be more economical to get a new one.
Oven Not Working After Power Outage? – Reason #2
Low Voltage
Likelihood? Low – will affect the fan. Call your lines company for details of the fault.
Fixable? Check for a tripped circuit breaker.
Lower than typical voltage will cause the fan to draw more current. This generates more heat and will eventually burn it out. A low voltage will also cause other components to malfunction such as any relays, contactors and the oven element itself.
Oven Not Working After Power Outage? – Reason #3
Unstable Frequency
Likelihood? Low – depending on the type of outage. Call your power lines company for details of the fault.
Fixable? Generally no – oven is probably a write off.
An oven is designed to operate at 60 Hz in America and 50 Hz in other places. Changing frequency is like changing gravity – it affects everything. When this frequency deviates resistance in the circuit changes. This can cause components in the oven to draw more current and burn out. This can affect almost every component of the oven.
Oven Not Working After Power Outage? – Reason #4
Lost Phase To Oven
Likelihood? High – if your oven is on two phases. Check the switchboard to see if there are two circuit breakers. One for the oven, one for the cooktop or something similar.
Fixable? Yes, wait for the lost phase to come back online. Talk to your line company for details.
If your oven is on multiple electrical feeds, it could be possible that one feed is still down. As mentioned earlier, one feed could be powering your cooktop and the other feed powering the oven. Check if the other part of the oven is still working. Make sure to turn on the switch. If it is working then it is a matter of time before the other phase comes back online and the oven works again.
How To Protect You Oven From Outages
As mentioned earlier a circuit breaker won’t protect your oven from a power outage. For this you will need a surge protector.
This will divert high unstable voltages to earth thereby protecting your oven. A surge protector is typically installed in your switchboard and looks like a small red circuit breaker with a green indicator showing that it is working. A surge protector is a good investment that will protect all appliances in your home.
Electricians Perspective
Fluctuating high voltages are the most common reason why ovens stop working after a power outage in my experience. High voltage will damage every component of the oven from the heater element to the fan. From the lighting to the thermostat. Everything is affected. The solution to this is to install a surge protector.
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