Radiation from Microwave Ovens

Hi, okay, so I got this on a university site, the normal text is the question, I think he copied an answer(Italicized) maybe from another forum or I dont know, and the bold text is the University's answer. I don't want to sound like I know everything in the world or even like I know quite a lot. But you had a question regarding "If a microwave oven door were to open while it was still on, what would happen? Could it hurt you?- JP"

Well ..Having the thought process that I have, kinda how should I put it? ...Stupid? or inventive or even in-between. Well, my microwave door did happen to come off. Magic Chef 900-watt microwave. Well, I did my best to try to fix it but the hinge on one side did not attach properly, therefore having a gap between the door and the appliance. Being me (stupid) I wondered if it would burn fast or would it gradually warm up. I slid my finger between...You probably dying to hear what happened... But it didn't gradually warm up at all. It was instant heat! It didn't scar me or anything like that, but sure scared the H*** out of me to find out it got so hot so quick. I didn't get any blisters either. But it just burned like touching something hot on the tip of my finger being that is the only thing I put in. Well you know the old adage, "You learn from your mistakes", stands true. lol - Anonymous

What a remarkable story! As much as I like to think I can predict what should happen in many cases, there is just nothing like a good experiment to bring some reality to the situation. Your microwave evidently sent a significant fraction of its 900 watts of microwave radiation through that crack between cooking chamber and door and roasted your finger instantly. This is a good cautionary tale for those who are careless or curious with potentially dangerous household gadgets. While I continue to think that serious injuries are unlikely even in a leaky microwave oven, you have shown that there are cases of real danger. Fortunately, you had time to snap you finger away. It's like Class 3 lasers, which are now common in the form of laser pointers and supermarket checkout systems: they can damage your vision if you stare into them, but your blink reflex is fast enough to keep you from suffering injury. Thanks for the anecdote and I'm glad your finger recovered.

Don't be so cheap, buy another Mirowave oven, you can get one for under $100

The biggest risk would be your eyes, which could be devastating to your sight. Microwaves "cook" by excitation of water molecules. We have a lot of water in our bodies, so that water gets hot very quickly and can even become steam. It is bad enough to get burned from the outside, but burn on the inside are another matter. Your eyes contain a lot of fluid and the tissue is very sensitive.

I do it all the time . . . do I look bad ?

"If one was to bypass the door safety on a standard microwave kitchen oven and leave it on, just what health hazards would be encountered?"

It just might "cook your goose."

And "your chicken" too.

I forgot to mention what's left of your brain!

The interlock is pretty much fool proof against all comers except fools and the mentally incompetent.

As a repairer of microwave ovens & other consumer goods, I can say that the inside of the oven is a resonant cavity& that microwaves at 2.45 GHz are kept inside by the shields- a tester measures the outside- 5mW/sq cm is considered safe close to the door seals- but the microwave leakage radiation reduces as the square of the distance- so if your oven is leaky(can hear on am radio), don,t stand close while it is cooking. If one was stupid enough to disable interlocks etc, & put your head inside, it would cook, just like food!.

In the past there were warning signs for people wearing pace makers not to enter a room that has a microwave. I don't know why and whether this is still the case.

People wearing pace-makers have an electrode wire that runs

directly to the heart. Should this wire fuction as an antenna, a

strong radio signal could kill.

Why would anyone want to disable a safety device especially one in your home where your family's health is at stake. If this issue is about leakage from the seals, there a instruments that will detect that. If you suspect that yours is faulty -- buy a new one they are really cheap these days. You can buy a new one cheaper that having a repairman make a trip to your home. After all your are talking about microwaves and they are especially dangerous to all living things, especially mucous membranes and all other areas of the body .

Every manufacturer lists the hazards, cautions, and warnings on the unit and in the users handbook. Read them carefully and heed the warnings.

In anticipation of your next question --- "NO" you can't use it to dry your cat after it has had a bath.

"Why would anyone want to disable a safety device especially one in your home where your family's health is at stake."

See Post #4 above: "The interlock is pretty much fool proof against all comers except fools and the mentally incompetent." Among these are the individuals who are of the opinion that the rules don't apply to them!

Yes -- I agree with you completely -- I only worry about the folks who have just enough knowledge to find a method of bypass and hurt themselves or worse yet someone else. -- and not the sense to stay safe.

Your statement below describes thios type of person extremely well ---

""The interlock is pretty much fool proof against all comers except fools and the mentally incompetent." Among these are the individuals who are of the opinion that the rules don't apply to them"!

. . . and some knowledge for others who have a failed catch and still use it. Our safety micro switch failed and the M-Wave would shut off normally when timed out, then when you popped open the door it would start up while you reached in; turntable going, light comes on, fan, everything. My wife (44 YO) and daughter (13 YO) just casually reach in and thought nothing about this . . . . and when I saw it I screamed at them to back away while I came up the side and pulled out the plug. They can't process the fact that the safety was there for a reason. When I repaired it I discovered that the micro switch that failed was only for the turn table and fan and lamp, not the magnetron. There are 2 switches in series for the magnetron, a NO and NC which must be both 'happy' to blast you, but the third switch was only for the accessory loads. But isn't it amazing, culturally, that they didn't think twice about just standing there, door open, turntable, lamp and fan going . . . . .

They told me : "Well . . . . nobody told us there is danger . . . bla bla bla".

But, who told me? Do you think my parents told me one fine day: "Now . . when you grow up, don't stand in front of open microwaves that have safety switches so you can't start them with the door open and try very hard to make some obvious conclusion from signs all over the planet about pacemakers. If you do, your kids will be born naked !"

Where has common sense gone off to?

Duhhhhhhhhhhhhhhhhhhhhh.

Ouch --- they were VERY LUCKY folks. I'm glad they didn't get hurt.

Sounds like some kind of failsafe RE-engineering is in order for that manufacturer. There must be a way to have these switches operate to meet a safe condition for all possible failures, for one or all of them.

The design is failsafe (kind-of), because the magnetron didn't operate, just the turntable, fan and light. The magnetron (that vibrates the water molecules and fries you and the food) can only energise if the NO switch and NC switch are both actuated, and they are 2 separate switches above and below the lever catch, so, the door must be closed and the lever must be fully 'caught' as well. 2 independent switches would need to fail at the same time (rare). But of course I didn't know that . . . I just see my daughter standing there with the door fully open and I hear the fan, then I see the lamp and turntable going so I screamed for her to move away sideways (not back up). Only when I traced the switch circuits did I find this double flip / flop back to back switch safety for the magnetron. It's a name brand.

I miss read the NO-NC part -- yes it seems failsafe -- but I can understand the scare you had, not knowing if the thing was operating or not. It would scare the h*ll outa me too.

I like the idea of having the cook setting lower than high and when the magnetron cycles off, pop the door open if needed.

Or turn the timer off or key in "stop or pause" if high is needed at the time. If nothing else, those safety switches are rather small to switch the actual magnetron current.

The door latch switches do not carry magnetron current- there are usually 3 relays on the control pcb in late micro ovens- in any case, hitting stop stops the magnetron. The happening where the turntable rotates when the door is opened is ,as has been said, simply failure of a interlock switch- easily replaced, or even repaired( they come apart,& the fault,loss of tension, dirty contacts, can be easily rectified).

Correct; thanks for saving me the 'reply' pointing out control logic v power management hardware. The door safeties are something like 22 ga wire and the magnetron looks to be 12 ga wire or there abouts to handle the watts. Nevertheless, when the safeties fail, you can blast yourself with the door open.

This is like saying the key switch in my car does not crank the engine. Sure there is not a number 2 wire going from my battery up my dash board and down to the starter motor, but there are 2 or 3 additional relays involved before we plow 800 amps to the motor.

Anyway, keep your safeties working or you will look my like pic!

I have a question about this. I have a newer version whirlpool microwave and was heating up a glass of water for tea.. After about 50 seconds I hit cancel, opened the door, and stuck my hand in the microwave to get the water.. I still heard the motor running down... and felt some warmth on my hand...

Was the thing still producing radiation? My hand is kinda tingly right now, even though I think its probably me overreacting to this... If it was going would I actually feel a burn? And if there was radiation contact, how bad is that for me?

Thanks

Hi Guest,

First, due to safety, do not take the advice below. Call a professional. Do not even read the advice below.

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You can buy a cheap microwave 'leakage' detector for $25-30 and share it with neighbors and family to justify the cost - http://www.google.com/search?hl=en&q=microwave+leak+detector&btnG=Google+Search

It's s good idea the check M-waves 1-2 times a year especially on high 'door' use units.

Here are the sounds of a microwave:

1) Cooling fan - not harmful

2) Turntable motor - not harmful

3) Magnetron - harmful (humming and 'load' noise, and it has a little diffuser blade wheel that vibrates as it is bombarded by m-waves >> put 2 minutes on the timer but set it for low heat and blast a full glass of water and you will hear the magnetron cycle on / off with the 'on' time very short since you put it on low heat; Then you can 'hear' what it sounds like 'on'; but the fan and turntable noise will be constant as they do not intentionally cycle with the heat setting). You may also see the lamp dim just a bit as the magnetron takes a lot of power and there will be a slight voltage drop to the lamp, turntable and fan and you'll see it, maybe, by lamp brightness cycling. Dim = magnetron energised. The fan may speed up and slow down just a touch for the same reason.

4) Wife - When you boiled over your soup and flooded the bottom with chicken broth and didn't clean it (you may be wondering how I know this sound)

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So, get your meter ready and pop open the door and see if the 'motor winding down' noise shows radiation on your $30 meter. Get it checked out and fixed.

I've never heard of a turntable or fan motor (or magnetron) winding down for more than 1/4 of one second >>> before you open the door it would be stopped. The little motors for fans and such do not have high inertia loads to keep them spinning long without power.