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motulist

macrumors 601
Original poster
Dec 2, 2003
4,236
611
So here's the situation; I have a very small kitchen and I want to permanently put my old laptop into the kitchen, but the only surface I have available to put it on is the top of the microwave oven. Do you think there's any risk to having my laptop and external hard drive permanently sitting on top of a microwave oven? This laptop is still a super useful machine that I don't want to get damaged, and there's lots of data I don't want to lose on the hard disks (it's backed up currently, but still).

"Is it safe?"
 
The microwave is brand new, I just bought it about a month ago. Do you think that makes a difference?

The difference is that in an older MW, the magnetron may be leaking or the shielding may not be as good.
 
What type of material is used to shield magnetrons? Because maybe I could get a slab of lead (or whatever the material is) and lay that on top of the microwave under the laptop, just to be sure. Would any laptop wires hanging down along the side of the microwave wind up picking up the microwave's EM radiation and conducting it right back into my laptop and external hard drive?
 
Some microwaves can interfere with WiFi signals. If you plan to use WiFi, you may see your signal strength affected by close proximity to the microwave.
...maybe I could get a slab of lead ...
That would certainly help protect your laptop from being scanned by Superman's X-Ray vision! :D
 
Some microwaves can interfere with WiFi signals. If you plan to use WiFi, you may see your signal strength affected by close proximity to the microwave.

Hmm, very interesting. Presumably though (and I guess I'm stating the obvious here, just to be sure), any interference would only occur when the microwave oven is actually cooking something, right?
 
Hmm, very interesting. Presumably though (and I guess I'm stating the obvious here, just to be sure), any interference would only occur when the microwave oven is actually cooking something, right?
Correct.
 
The microwave is brand new, I just bought it about a month ago. Do you think that makes a difference?

Yeah, older microwaves didn't have as good shielding and needed to be checked often. Newer ones are a lot safer on that front.
 
What type of material is used to shield magnetrons?
I'd think there's actually two different things that could theoretically be dangerous to the computer; leaking microwave radiation, which in sufficient quantities could well induce currents in the metal parts of the computer and maybe fry things, and stray magnetic field from the power source or magnetron, which (as with any magnet) could theoretically do bad things to digital hardware).

Both would be blocked by a Faraday cage--basically a metal box connected to a grounded conductor. In theory, so long as your microwave has a ground pin on the power cable (which I certainly hope it does) the case of the microwave itself should effectively be a Faraday cage.

So far as my very limited understanding of ovens go, that's basically the way the things operate, although maybe they rely more on reflecting the microwaves back in than the grounding.

Meaning, basically, you should be ok (although to be honest, I probably wouldn't do it myself). If you wanted to be paranoid a reasonably-thick piece of metal between the microwave and the laptop connected to your house wiring's ground would be an extra layer of safety.

Would any laptop wires hanging down along the side of the microwave wind up picking up the microwave's EM radiation and conducting it right back into my laptop and external hard drive?
Probably not, but that's the one thing I'd actually be a little worried about (if you had, say, the DC power cord running right along the AC power cord of the microwave).

But then my experience with signal noise on unshielded wires in data collection systems has probably made me unnecessarily paranoid--hard drives are a lot less sensitive to errant magnetic fields than people think.

Note that, while I work with this stuff, it's been so long since my E/M physics classes that I probably have no idea what I'm talking about and am giving awful advice. But then, it's the Internet, right? (And I'm amused at some of the paranoid insanity you get when you search for "block microwave radiation" in Google. Did you know that jet contrails are part of the New World Order's plan to chemically neuter the population?)
 
I'd think there's actually two different things that could theoretically be dangerous to the computer; leaking microwave radiation, which in sufficient quantities could well induce currents in the metal parts of the computer and maybe fry things, and stray magnetic field from the power source or magnetron, which (as with any magnet) could theoretically do bad things to digital hardware).

...both of which can be induced from any source of RF in a typical non-shielded environment. It's not an issue.
 
...<snip>

Wow, thanks for the detailed and knowledgeable response!

I am happy to report that my laptop has now survived being "nuked". I've had my laptop sitting on top of my microwave for about a day now, and I just turned on the microwave for 6 minutes with the laptop sitting on top of it, and right now I am writing this to you on the same said laptop. Thank you UL Laboratories, your little sticker on the back of all my appliances actually means something! I did take the precaution of putting my laptop to sleep while the microwave was running, which I think is a reasonable precaution to take in this scenario, which I could easily live with. Really I think the biggest danger to my laptop in this setup comes from more banal sources than EM radiation. The top of the microwave gets quite warm to the touch through simple heat convection, and there is often steam rising out of the food I cook in the microwave oven. So the biggest danger is probably from the usual old foes of electronics - heat and moisture.
 
I did take the precaution of putting my laptop to sleep while the microwave was running, which I think is a reasonable precaution to take in this scenario, which I could easily live with.
Actually, I'd wager that if it's going to do something bad, it won't make the least bit of difference whether the Mac is awake or asleep--even asleep the RAM is still live and the hard drive won't care whether it's off or on if there were to be any problems. Since it survived, I'd just go with it. If it crashes, of course, I'll stand corrected, but it's certainly no more likely to break anything.

So the biggest danger is probably from the usual old foes of electronics - heat and moisture.
This, entirely true--spilling water on your laptop is pretty much guaranteed to break it, and there's a lot more liquid in your kitchen than the average office.


(Also, not sure how knowledgeable I am in practical terms, but I've got to feel like I got something out of all those years of classes.)
 
It is perfectly safe. There cannot be leakage through the top of the oven; as for leakage from the top of the door, this is highly unlikely to be a problem, unless there is a problem with the door - being warped or damaged for example.

The only precaution you might want to take is to elevate the computer & hard disk slightly because of heat generated from the oven's light & the blower. I've added small cork feet to my Time Capsule (it's not on top of any of my 50+ microwave ovens) because it gets hot - I lost one because of its internal heat. The same thing with your computer & disk drive. You don't want to add any heat from the microwave oven ( it is NOT microwave heating!!!). So, add feet, or put a few layers of newspapers between the computer and the oven top, or any other way of provided insulation, air circulation, etc.
 
Two suggestions....

1) If you are that worried about the contents of your laptop, at least make sure you are doing backups. 'nuff said.

2) I'd be more worried about any magnets and vibrations in/from the MW than the emissions. Put your laptop on top of thick cork matt. I know that cork does not shield from the magnets, but the putting some distance in between will help. Make sure though that there is air flow between the bottom of the laptop and the matt, since Macs use the bottom to help cool the system.

3) Watch out for liquid spills

OK, that was 3...
 
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