Breakers tripped, fuses blown! Help me with my Magic Chef microwave!


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Old 03-20-13, 02:37 PM
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Breakers tripped, fuses blown! Help me with my Magic Chef microwave!

I inherited a 2004 Magic Chef microwave from a friend a few years ago.

The microwave was plugged into a standard sized power strip, which was then plugged into a standard grounded kitchen outlet. (My apartment does not have a dedicated circuit for the microwave). I was using the power strip as an extension cord only-- nothing else was plugged into it.

Every few months (or weeks- it was intermittent), the microwave would trip a couple of breakers while I was using it (kitchen and living room). It did not happen consistently.

One day I came home to find the microwave was totally non-functional. No power, as if it were not plugged in at all.

I used a multimeter to confirm that the fuse had blown. (It was a 20 Amp, 125 Volt fuse). I purchased a 20 Amp 250 Volt fuse replacement for it, and it worked. I plugged it into the old socket, but this time directly into the wall (thinking perhaps the power strip was causing the issue).

When I woke up the next morning, it was dead again. Blown fuse.

So, my question is:

- Could the microwave itself be the cause the malfunction?

- Is the fuse repeatedly blowing because I'm not on a dedicated circuit?

- Or is it something else entirely? Or both?

The issue is one I need to take up with my landlord. Current building codes in my city require dedicated circuits for microwaves, so if I pushed the issue I could have him install one. But if there could be other causes for the problem, I don't want to force him into an expense that won't fix the issue.

Thanks everyone.
 
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Old 03-20-13, 03:29 PM
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What else is on the circuit?
 
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Old 03-20-13, 04:32 PM
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It's the kitchen breaker, but it's a small apartment kitchen. Is a fridge generally assigned to its own breaker switch? Otherwise, we're looking at standard appliances... an modern oven, an old gas range (no electronic components), and a 4 slice toaster (not toaster oven). I'm not sure exactly what else would be in the same circuit.
 
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Old 03-20-13, 05:38 PM
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Most cases a cord connected counter microwave would not be required to have a dedicated circuit, but you can see why is would be a good idea. If the microwave was not sitting on the kitchen counter, and had its own shelf, or was a wall mounted one, you would be required to have a dedicated circuit.

Here's the rub: Your apartment is likely grandfathered in to an older code and your landlord may not have to do anything.

But the part I an a little confused about is the fuse is blowing even without running the microwave, correct? If no appliances are being used, (running) no fuses should be blowing.
 
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Old 03-20-13, 05:54 PM
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Could the microwave itself be the cause the malfunction?
More than likely not. It's just one thing connected to a problem circuit. Now, like Ray asked, what else is on that circuit ?

It may not be an item..... it could be a device or a wiring problem.

If you aren't sure what else is on that circuit.......turn it off and see what doesn't work anymore. Check all the receptacles whether or not something is plugged into them.
 
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Old 03-21-13, 02:24 PM
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You know, I think I figured it out.

The refrigerator has its own circuit.

The kitchen circuit, into which the microwave and toaster are plugged, is shared with the living room circuit, which has a 40" CRT television, surround sound stereo, Wii, DVD player, small analog/digital TV converter box, aerial antenna, and fluorescent torchiere lamp plugged into it. (To get all these devices powered, I've split the standard two outlets into 6, and then plugged a power strip plugged into one of the 6.)

Now that I think about it, the breaker would always trip while I was watching TV and using the microwave (as it always interrupted while I was watching a show). However, the fuse blowing on its own (when the microwave was plugged in but not actively operating) is a new thing. Like I said originally, the fuse blew overnight-- I woke up the next morning to find it dead. The TV, etc. remain plugged in all the time, and sometimes I carelessly leave components (like the Wii or DVD player) on.

So, it sounds to me like the circuit is overloaded. I am told that in the city of Los Angeles, there is a requirement for microwaves to be on dedicated circuits, and older apartment buildings are not excluded from this requirement. But I'm no expert in this field, and would appreciate clarity from anyone here who might be.

I've attached a pic of my circuit breaker box for reference. (Not sure, but I believe the top 2 are probably my air conditioner, and the other unlabeled 15A circuit is probably the dining room area.)

Thanks
 
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Old 03-21-13, 03:07 PM
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If this fuse that is blowing is internal to the microwave oven then I would hazard a guess that it is the oven itself that is the problem.
 
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Old 03-21-13, 03:36 PM
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It looks to me that the fridge has it own circuit. Refrigerators only draw about 7 amps when the compressor is running. If you can, I would plug in the microwave there.
 
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Old 03-21-13, 03:52 PM
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Yes, as Furd asked where is the fuse that is blowing?
 
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Old 03-21-13, 04:03 PM
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The fuse that is blowing is the internal microwave fuse.

So if all my gear is on on one circuit, on the 20A breaker, that's 2400W at 120V. That means the microwave is 950W on full power. The CRT TV is going to pull 300W probably, etc.

So, what about the DVD, Sony surround sound stereo/amp, Wii, flourescent torchiere lamp, Mohu leaf amplified antenna, and Zinwell ZAT-970A digital/analog converter box?

What exactly makes you think it's a defect in the microwave vs. a strain on the circuit?

I'll check to see if I have an additional outlet for the dedicated refrigerator circuit.
 
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Old 03-21-13, 06:00 PM
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I've had microwave oven fuses blow due to low voltages so you need to check the voltage when the microwave is running but it is more likely the microwave is just bad.
 
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Old 03-21-13, 06:12 PM
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What exactly makes you think it's a defect in the microwave vs. a strain on the circuit?
In your first post (I didn't see it on the first read) you said you had to replace the internal fuse. That 20 amp fuse does not usually blow out unless there is an internal problem in the microwave.
It's actually pretty rare for that fuse to blow without using the microwave. Since it did ...that would suggest that the microwave may have a wiring problem inside unit. I would have microwave checked out for problems.

As far as the required dedicated microwave receptacle ...... code requires that on a permanently installed unit.... not a counter top one.
 
 

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