Toaster Trips House Circuit Breaker
Our toaster started to trip the 10 Amp circuit breaker when it was turned on. My wife, being a smart lady, thought it might be due to the fact that the microwave oven, toaster and jug were being used at the same time. She turned off the jug and microwave and tried the toaster. The circuit breaker tripped again. She disconnected the power board that the toaster was on and it tripped again (you can see why I married her…)
One of the hardest parts of this repair was removing the screws that held the plastic body onto the actual toaster – I have never seen these types of screws before! They weren’t even safety torx or something similar. Anyway, an electric drill sorted out that problem – with a little time and patience.
Once I had the cover off, I could see how clogged it was with crumbs. It really needed a clean! I carefully brushed out all the burnt crumbs. To test the unit, I ran it from my isolation transformer and a RCD power block. Before actually starting the unit, I decided to do some basic checks first. 
Measuring the resistance of the circuit with the switch in the closed position gave a result of 31.8 Ω.
I next decided to power up the toaster and see what it did. I was surprised – it seemed to work fine. What had changed? Was it a fault with the house circuit breaker? Well, no, since other appliances worked fine. It was just the toaster that had tripped the breaker. Further investigation was required. Next step was a current draw test.
I have made up a simple unit for testing current without having to break a circuit.
By using a power point and splitting the outside shielding (making sure to keep the actual wiring shielding intact), a current clamp can be fitted onto one of the wires (either active or neutral).
By using Watt’s Law, (P = V x I or Power in Watts = Voltage x Current) I was able to calculate that the lower wattage should draw 6.875 Amps and the higher end of the wattage should draw 7.5 Amps.
After testing with my current clamp, the results showed a healthy 7.47 Amps. So with this reading, why did it trip the house circuit breaker? Only one reason made sense.
With the accumulation of crumbs that had been toasted, a build-up of carbon had amassed. Carbon being conductive in this form was enough to create a component short between the resistance wires in the toaster, therefore decreasing the circuit resistance. This in turn, allows the current to increase to a point where it would trip the circuit breaker. I would have liked to prove this, but as I said, I cleaned the toaster before pulling it apart.
So what is the moral of the story? Two things.
- Leave the appliance in the state that it was given to you so that you can imitate the fault
- Even things as basic as toasters need maintenance!
But most importantly, I now have a happy wife with a working toaster! I was able to video this repair if you are interested. The link is below:
This article was prepared for you by Mark Rabone from Australia.
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Note: You can check out his previous repair article below:
https://jestineyong.com/repair-automotive-clock/
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Albert van Bemmelen
September 19, 2016 at 5:10 pm
I recently bought a new Toaster that like yours also was made in China, Mark. But not because it was defect or short circuiting but only because it was old and because I read about the Asbestos that is used in these appliances still made before 1991. And I could not read anywhere on the device in what year my old Toaster was made of which I had repaired its bad power cable a few times before. As it turned out my new Toaster used the same quantity of Watts and also was China made. And probably still contains Asbestos plates to hold the Heating Wires. And maybe therefore is only made in China? I kept my old Toaster because it still works fine. My new Toaster is larger and doesn't get hot on its outside. So it hopefully is a bit safer. I noticed that my new Toaster however produces a very large blue light when I switch of the Electric AC current a few seconds just after I had turned it on. Likely because of the Heating Wire resistance being very low after still being cold? Something that easily occures by pressing the bottom STOP button on the Device.
Mark
September 19, 2016 at 8:55 pm
Hey Albert,
You can't beat the old faithfuls!
Interesting about the blue light. I can't say I've heard of that before. A fault perhaps? It's not arcing at the switch contacts?
Albert van Bemmelen
September 20, 2016 at 12:09 am
I haven't opened my new Tefal Express model SERIE T19-C, REF: TL360130/3D-1116R yet, but I think it is indeed arcing on the off switch contact inside. The Blue Light can be seen on the out- and inside. And the Powerconsumpsion is inbetween 840 to 1000 Watt (adjustable).
Cheers.
Luciano Khware
September 19, 2016 at 5:40 pm
Hello Mark,
Thanks for sharing: you have a working toaster and a happy wife. Congratulations!
Mark
September 19, 2016 at 8:56 pm
To be honest, I'm more interested in the happy wife....
Parasuraman
September 19, 2016 at 6:25 pm
Great electronic experts, both, and that is a rare couple! All the best!
Mark
September 19, 2016 at 8:58 pm
I can't take the credit - she is a lot smarter than me.
Andre Gopee
September 19, 2016 at 9:27 pm
Nice article Mark. However, I try to tell people stop using those slice bread toasters because of the same reason of the crums build up at the bottom and can cause a fire. Also you can never tell what kind of crawly creatures like cockroaches etc. have gotten in there and we eat those bread. So be aware.
Mark
September 20, 2016 at 4:09 pm
Thanks Andre, I think I might skip toast for breakfast today.....
Yogesh Panchal
September 20, 2016 at 12:46 am
Mark,
Regular maintenance of any device will help the device to revive.
Thanks for sharing.
Graeme Partridge
September 20, 2016 at 5:40 am
Mark,
Nice article, point 1. Is very pertinent I think we have all been caught out by this at one time or other.
I believe that it is more energy efficient to use a toaster rather than an electric grill? although I understand the point about hygiene.
Gerald
September 20, 2016 at 10:54 am
Hi Mark, I love the video, well done, you are a good teacher and great presenter.
Just as a matter of curiosity, was it the Circuit Breaker (10A) or the ELCB part of it that made the CB tripping? Because a 10A short circuit is a big bang, while the ELCB trips silently with only 30mA of leakage current.
Cheers,
GM
Mark
September 20, 2016 at 4:14 pm
My wife was home at the time, but she stated that it was the 10A circuit breaker. We have a separate ELCB for the circuit board.
Cheers
Thanks for your comments on the video as well.
Don't forget to subscribe.........:)
Robert Calk
September 22, 2016 at 1:13 pm
Thanks Mark. Of course I already saw your video since I'm subscribed to your YouTube channel. You know the old saying, "When mamma is not happy, nobody is happy".
Mark Tembo
September 22, 2016 at 5:13 pm
I like this article, especially on how you calculate on minimum and maximum power ratings the device can take. At times, we often do forget some basic principles like this when doing fault-finding. Logic thinking as this one can really help you fix some complex problems. Thanks again for sharing.
Regards,
Mark T.
Mark
October 8, 2016 at 7:29 pm
Hey Mark,
I agree, we have to start at the basics. My motto is 'Making the complex, Simple'
I have been in the automotive industry for 33 years and yet I still see technicians 'throw parts at it' in the hope of a repair. I must say, it frustrates me, when simple, logical diagnosis can make the repair quicker, cheaper and more satisfying for the tech!
Bulent NUR
September 25, 2016 at 5:15 pm
Thanks good job! Video yummy.
Ulises Aguilar Pazzani
September 27, 2016 at 12:15 pm
very professional on the measuring