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The Critical Eye!

Michael Leavitt’s professional inspection related blog.

Sparks in the Microwave

Sparks in the Microwave

Michael LeavittHave you ever turned on your microwave and sparks started to fly? It is then that you realize that there was some type of foil in whatever you were trying to cook. So you remove the foil portion of the item and voila, everything is normal. So what happens when you check the item and there is no foil or metallic item? That is what happened to fellow home inspector, Victor Sparks (Yes, that really is his name), from Sacramento, California.

Victor shared,

“Shortly after turning the microwave on today at my inspection I noticed a small electrical storm going on inside.

I shut it off immediately and could smell smoke inside. Luckily, the owners of the house were there and they informed me that this happens ONLY when the TV satellite cable box is connected and the TV is on! I will of course defer this to an electrician, but has anyone else ever had this experience either on the job or at home? If so, what was the cause and the fix? I am assuming the microwave is on a dedicated circuit, so I'm stumped. Thanks in advance!”  Victor Sparks - Sacramento, Ca.-

I shared playfully,

“Demonic possession?”  Michael Leavitt - Orem, Utah - 

Victor responded, “

“I knew, those voices I heard weren't coming from inside my head!” Victor Sparks - Sacramento, Ca.-
And I said,

“Victor: Those voices are from your mis-spent youth. J But on a serious note, did you get the make and model? This is a great scenario to share with the tech engineers at the manufacturer.

Did you test the outlet?

It would be interesting to know what the voltage was and the ground impedance. This would have been a perfect scenario to use a SureTest or the Amprobes. If it were my house I would have taken a good extension cord from another circuit and see if the same issue occurs. It is either the power coming to the unit or a major malfunction within the unit. And then if it were neither of those, then I would revert back to demonic possession.” Michael Leavitt - Orem, Utah -  

Victor responded,

“I wish I would have thought of the extension cord idea, but the outlet was behind a big piece of furniture and I wouldn't have been able to get to anyway. And no, I didn't grab the make and model number either...sorry guys and gals...I'll see if I can get it from the owners.” Victor Sparks - Sacramento, Ca.-

And I attempted some levity with,

“What?... Now you‘re gonna tell me you didn’t get a photo of the sparking and smoking either. That’s why we have all of the technology so that we can capture the action. Oh well, maybe next time.” Michael Leavitt - Orem, Utah -

This is where online interactions get good because others can chime in with their thoughts, knowing that probably none of us are experts with the particular issue, yet all of us have experience using microwaves.

“Victor was probably running for the fire extinguisher Michael. I might have been.“ Larry Stamp - Olympia, WA.- 

“Dad was hiding the TV remote from the kids in the microwave until he got home and you fried it.” Garry Blankenship - Monroe WA

“Was the microwave empty? I have seen warning labels on newer microwaves that state to never operate when empty. Im not sure why possibly something to do with the auto sensing mechanism. I too had a similar experience and the microwave would not operate after all the sparks. I now always carry an empty plastic water bottle in my truck, fill it about half way and then operate the microwave. I had the glass on the microwave door shatter on another inspection. The turntable was misaligned came in contact with the window and it sparked and shattered. I now check the turntable alignment before operation also.” Don Powell - Sacramento, Ca.

“I used a plain coffee cup filled with water to test it. Also, the owner turned off the satellite box and had me test it again to prove that it would spark only when the box was on. Sure enough, there were no sparks flying when I retested.” Victor Sparks - Sacramento, Ca.-

And then Geoff Stewart, from Lincoln City, Oregon, shared a very interesting YouTube video that taught most of us inspectors something new...


I just love interacting online with other home inspectors because we encounter the strangest issues and the interactions lead to incredible research, stories and information. Geoff’s video link reminded me of the plate from years ago when my then 14 year old neighbor, Tanner Bean, took our old microwave and removed the magnetron and he was explaining to me all of the different parts of a microwave oven. He proceeded to create a ray gun that wouldn’t be considered safe or legal in any municipality. Tanner was, and is, an electrical genius. He was showing me how the energy was dispersed through the oven and explaining all of the charring marks. But there was never any mention of possible interference by a satellite system.  And just so you know, in my further studies since Victor shared his issue, I did not find anything regarding satellite systems, but I did find some great nuggets of truth about microwave ovens sparking.
Here is a great how to video showing the removal of the waveshield and the re-installation...

But I know what you really want to see is a unit arcing and then exploding. Well YouTube is filled with videos of all types of explosions, and microwaves are no exception.
But let’s look at one that arcs. The young man is quite excited with the discovery and he can’t wait to share the experience with his Mom by not telling her and allowing her the same self-discovery experience...


The best exploding video does not allow embedding, so here are 3 screenshots and the link for you to go see it for yourself...




So what do we learn from all of this? Here are the top 10 items I learned...
1) Microwaves can spark for a lot of reasons
2) The waveguide cover disperses the power generated from the magnetron
3) The waveguide cover can be white plastic, silver metal, or even foil covered cardboard.
4) The waveguide cover must be kept clean.
5) The waveguide cover is a replaceable part.
6) Operating the microwave without the cover diminishes the cooking efficiency of the unit.
7) The waveguide cover also protects the magnetron from exposure to food splatter.
8) And even though one of the referenced videos tell you to remove the shield and continue to use the unit without it, that is NOT recommended.
9) Sparking can also come from lead paint used on some dishes.
10) Sparking in microwaves will always capture my attention and hold my interest.

And finally,


This came from Helen at Espares regarding the cleaning of the inside of the microwave.
1) Take a glass measuring cup and add about 2 to 3 cups of water (Helen said 300 ml).
2) Squeeze in a half a lemon and place the lemon in the water as well.
3) Run for 5 minutes on “High” power.
4) Then wipe away all of the interior condensation and it is clean.
That is a great tip Helen.
Hopefully all of this information was both fun and informative...
Make it a great day!
Michael Leavitt - Orem, Utah -

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