Spudz said:
We are finsihing up a new construction home, and have a Viking
Microwave on a 20 amp circuit in the kitchen. This is the only device
on the circuit. The microwave cooks fine, but sometimes just closing
the door on the microwave trips the breaker! I have moved the oven to
another outlet and it doesn't trip other breakers. ANy ideas what
might be happeing? I can't imagine closing the door would draw a lot
of current! We have used other devices on the same outlet with no
problems.
thanks!
To reply via email remove spamnot
A couple of additional possibilities. Note that some circuit breakers will
pop before a slo-blo fuse in the same line. Think door switches and read on.
Food material can gather at the operating pip of any of the door micro
switches. This can be as small as a very light smear of something sticky.
The effect is to slow down the operating speed of one or more switches. This
will cause an intermittent door switch timing overlap when either opening or
closing the door. The actual switch sequence, the switch affected by food
debris, and the particular design of the oven will cause a variety of
different scenarios. THIS IS A COMMON FAULT. You may need a 10X jewellers
loupe to see some food smears which are fully capable of causing a switch to
hang long enough to blow a fuse or trip a breaker.
Another fairly common cause for a switch to hang and disrupt the interlock
sequence is much harder to detect and has a greater capacity to have you
re-working ovens at your expense. This primarily affects the switch in the
sequence that acts as the crowbar, but can also affect even clean
primary/secondary switches after some years use.
If an oven has had a history of one or more fuses blown without a fault
being discovered, the crowbar switch will have had some serious energy fed
into its shorted contacts. This ALWAYS leaves a roughened area on the
contacts. Roughened contacts do not slide as easily as pristine ones and the
slowed-down switch is now likely to blow a fuse intermittently, ***even if
the cause for the original fault is found and corrected.***
Best practise, is to ALWAYS, if possible, examine with a loupe the contact
area of crowbar door switches. Trust no door switches that have switched
full current through them to blow the main fuse. If you have a customer oven
or two that blow switches every week or so, suspect food debris and/or
roughened contacts.
In my experience, most door switch problems with microwave ovens are caused
by (sometimes) tiny amounts of food. I used to buy, and use, 5000
microswitches every 6 weeks or so for this very reason. You cannot
effectively clean food debris off switches. Always put new switches into
clean housings. To do otherwise is to risk doing the job again ***at your
expense***
