How can I tell if my microwave is safe?

June 20, 2006 6:12 AM

How can I tell if my microwave has become unsafe?

When my microwave is on it seems to interfere with both my cellular reception and the signal quality of the portable phones in the house. This makes me a little worried that whatever sort of protective lining is on the microwave isn't doing its job of stopping the harmful rays. How can I know whether this is needless paranoia? The microwave is rather new.

Aside: I've heard that if the protection is of proper strength then a cellular phone, placed in the microwave, should not ring when called; seems like it could be true, and equally plausibly could be total nonsense. But mine does ring in there.

posted by louigi to home & garden (12 comments total)

Your microwave sounds like its fine.

Normally functioning microwaves are allowed to leak power into the surrounding environment. This takes the form of 2450 MHz radio waves, which would interfere with any 2.4 GHz portable phones in your home.

You can reduce the impact of the microwave by setting up some shielding or moving the items from their current locations.

More info:
http://www.newton.dep.anl.gov/askasci/eng99/eng99331.htm
posted by SemiSophos at 6:43 AM on June 20, 2006

And linkified: http://www.newton.dep.anl.gov/askasci/eng99/eng99331.htm
posted by SemiSophos at 6:43 AM on June 20, 2006

Stand near it while operational with a chocolate bar in your pocket?

In all seriousness, I think that any device operating with radio/microwave frequencies such as these could easily interfere with a cell phone and portable at close range. Change the channel, etc. (Upgrade to 5.8 GHz?)

And call the manufacturer hotline (heh) of your microwave and see what they say. I'm sure there's a number you can call if you're concerned that it's cooking your giblets, but the reality is that any energy expelled outside of the microwove won't be travelling very far, so just don't stand in front of it while it's operational.
posted by disillusioned at 6:44 AM on June 20, 2006

The only way I know is to use a microwave detector tuned to the frequency of m-ovens. Myabe there's some product like that on the net.

As for the chocolate bar empiric test...I doubt it would be indicative, but of a massive leak ? Anyway I wouldn't STAND there with the bar :D !
posted by elpapacito at 6:51 AM on June 20, 2006

Here's a section about leakage. Meters and testers can be found all over with prices that vary widely. Here is one example (never owned this kind).

I'd take it to an appliance repair store to see if they can test it for less than the cost of a meter.

Anecdotal story - my dad gave me his old microwave when I got out of college. Being a consummate EE geek, he also brought a tester with him in case the oven got damaged in transit. We ran it and looked for leaks and found none. I asked how he knew the meter was working. He said that he didn't - he'd never used it before. He put it inside the microwave and turned it on. The meter worked for about 1/2 second before it exploded.
posted by plinth at 7:31 AM on June 20, 2006

THE DETECTO CARD - $4.99
posted by 517 at 7:53 AM on June 20, 2006

(This should have been in the last post) Available at most hardware stores.
posted by 517 at 7:55 AM on June 20, 2006

Hmm, one could also use something like Wi-Spy It could give you a signal strength in the 2.4 range. A bit expensive for microwave checking though.

Do note though, that most 802.11b/g equipment works on absolutely tiny amounts of signal, compared to a microwave. A less than top of the line (read: non-shielded) will leak enough signal to cause a disruption.
posted by zabuni at 8:42 AM on June 20, 2006

The only way I know is to use a microwave detector tuned to the frequency of m-ovens. Myabe there's some product like that on the net.

The cordless phone's do that, although as mentioned, they're very sensitive, so interference is normal. If there's no physical damage, you're probably OK.

Aside: I've heard that if the protection is of proper strength then a cellular phone, placed in the microwave, should not ring when called; seems like it could be true, and equally plausibly could be total nonsense. But mine does ring in there.

Cellphones operate on different frequencies to microwaves, and the shielding (specifically the holes in the mesh in the door) will be tunes to that rather than the phone, so this doesn't really indicate anything. Try it with a cordless phone instead.
posted by cillit bang at 8:59 AM on June 20, 2006

It seems to me that the only real risk of a microwave leak is that you could get burned, and even then, that would require standing still, right near the source of the leak, for some time. Outside of the resonant cavity of the oven, any leaked microwaves won't carry much power and won't travel far. Personally, I wouldn't worry about it.
posted by dseaton at 9:12 AM on June 20, 2006

It's a matter of power. The RF generated by microwave ovens is only dangerous to living creatures at moderately high power levels. Most microwave ovens run at a thousand watts or so, and I'd be seriously concerned if 50 watts were leaking.

But to interfere with phones and wifi, a few milliwatts is all that's needed. At those kinds of power levels there's no threat whatever to living flesh.

Shielding is a matter of degree. It is impractical to stop all leakage; they reduce it to well below the danger level, and that's really all that's needed. It's not implausible that it could still leak enough to cause transient interference with RF devices.
posted by Steven C. Den Beste at 11:28 AM on June 20, 2006

By the way, that's the reason why you see (or used to see) signs in restaurants saying Microwave ovens in use, pacemaker patients take note. There was some leakage that was not enough to be a hazard to normal people, but which could conceivably cause enough EMI to louse up the electronics of pacemakers.
posted by Steven C. Den Beste at 11:30 AM on June 20, 2006