6 ms·

I remain in awe that we trust the very cheapest plastic under repeat load and thermal cycling to form a -40dB seal, turning 700W into 70mW. Also, it seems that

I remain in awe that we trust the very cheapest plastic under repeat load and thermal cycling to form a -40dB seal, turning 700W into 70mW. Also, it seems that the outer metal shell of the device forms an active part of the circuit, so if it isn't plugged into a grounded outlet it sits at lethal potential. Then there is beryllium oxide in the thing... I kind of doubt an independent inventor could bring this to market with today's startup climate.

dhdc 5y ago
A faraday cage does not require grounding to work, but its still recommanded to properly ground microwaves. Also, unless your electrician had a catastrophic fuck up, the metal cage will never be at live voltage, with or without grounding.
- ganzuul 5y ago
  The specific scenario I have in mind is a student living on their own for the first time, cooking with a microwave in their room. Many catastrophic fuckups that we were quick to forget took place during this phase in life. You might take apart a microwave oven and discover that there are actually several pieces of sheet metal in them. Expensive ones connect them by staked wires. The capacitor is usually rated for 2000 volts and it packs quite a punch.
  - dhdc 5y ago
    How does a student living on their own has to do with anything about microwaves having "lethal potentials"? And what does the high-voltage capacitor has to do with sheet metals? I'm sorry, but I really cannot follow your logic here.
    - ganzuul 5y ago
      Have you ever looked inside a very dirty computer? It's quite simple.
KennyBlanken 5y ago
> I remain in awe that we trust the very cheapest plastic under repeat load and thermal cycling to form a -40dB seal, turning 700W into 70mW It's the metal grid in the window (with holes smaller than the wavelength of the microwaves), and the metal shell of the cavity, not any "plastic." The same reason the metal grid works is why there doesn't need to be a perfect door seal. As long as as the gap is smaller than the wavelength of the microwaves, it's fine. > Also, it seems that the outer metal shell of the device forms an active part of the circuit, so if it isn't plugged into a grounded outlet it sits at lethal potential. The shell doesn't sink RF, it reflects it. GFCI outlets (required in many areas for kitchen outlets) trip at 5mA differential between hot and neutral. No appliance is designed to sink current into ground unless there's an electrical fault. > Then there is beryllium oxide in the thing... Beryllium oxide hasn't been used in microwaves for a long time, and it presents zero risk unless the magnetron is smashed. Recommended reading for you: https://www.dannyguo.com/blog/my-seatbelt-rule-for-judgment/ https://www.dannyguo.com/blog/my-seatbelt-rule-for-judgment/ https://www.psychologytoday.com/us/basics/dunning-kruger-effect https://www.psychologytoday.com/us/basics/dunning-kruger-eff... Edit: They can interfere with WiFi because a microwave could leak a tenth of a percent of its nameplate power and it would overpower your access point by anywhere from 1x to 10x. Access points can, on certain bands, have radios up to ~1W, but 125-250mW is much more common. It would also be completely harmless even if you were standing inches away from whatever the source of the leak was. Microwave RF energy only becomes dangerous when it is strong enough to heat up parts of your body that cannot cool themselves quickly due to having little/no bloodflow, like your eyes. You could put a parabolic antenna on your home wifi AP and standing in that beam would expose you to more RF energy than your microwave. I don't know why HN suddenly has a "DANGERS OF MICROWAVE OVENS!" boner this week...this is I think at least the second article on the subject of the 'dangers' of microwave ovens. Regarding "the door gap is a long line" - that would be relevant if the beam were aimed parallel (or close to parallel) with the gap...
- Retric 5y ago
  > The same reason the metal grid works is why there doesn't need to be a perfect door seal. As long as as the gap is smaller than the wavelength of the microwaves, it's fine. The issue is the gap in a door normally forms a long line. The fact they interfere with WiFi should make it obvious the average microwaves faraday cage is far from perfect.
jodrellblank 5y ago
> "I kind of doubt an independent inventor could bring this to market with today's startup climate." Especially the kind of inventor who created microwaves for experiments with reanimating frozen hamsters, cough James Lovelock. (Tom Scott's video "I promise this story about microwaves is interesting" which includes a brief interview with James Lovelock last year at age 101 - https://www.youtube.com/watch?v=2tdiKTSdE9Y https://www.youtube.com/watch?v=2tdiKTSdE9Y )

dhdc 5y ago

A faraday cage does not require grounding to work, but its still recommanded to properly ground microwaves. Also, unless your electrician had a catastrophic fuck up, the metal cage will never be at live voltage, with or without grounding.

ganzuul 5y ago
The specific scenario I have in mind is a student living on their own for the first time, cooking with a microwave in their room. Many catastrophic fuckups that we were quick to forget took place during this phase in life. You might take apart a microwave oven and discover that there are actually several pieces of sheet metal in them. Expensive ones connect them by staked wires. The capacitor is usually rated for 2000 volts and it packs quite a punch.
- dhdc 5y ago
  How does a student living on their own has to do with anything about microwaves having "lethal potentials"? And what does the high-voltage capacitor has to do with sheet metals? I'm sorry, but I really cannot follow your logic here.
  - ganzuul 5y ago
    Have you ever looked inside a very dirty computer? It's quite simple.

KennyBlanken 5y ago

> I remain in awe that we trust the very cheapest plastic under repeat load and thermal cycling to form a -40dB seal, turning 700W into 70mW It's the metal grid in the window (with holes smaller than the wavelength of the microwaves), and the metal shell of the cavity, not any "plastic." The same reason the metal grid works is why there doesn't need to be a perfect door seal. As long as as the gap is smaller than the wavelength of the microwaves, it's fine. > Also, it seems that the outer metal shell of the device forms an active part of the circuit, so if it isn't plugged into a grounded outlet it sits at lethal potential. The shell doesn't sink RF, it reflects it. GFCI outlets (required in many areas for kitchen outlets) trip at 5mA differential between hot and neutral. No appliance is designed to sink current into ground unless there's an electrical fault. > Then there is beryllium oxide in the thing... Beryllium oxide hasn't been used in microwaves for a long time, and it presents zero risk unless the magnetron is smashed. Recommended reading for you: https://www.dannyguo.com/blog/my-seatbelt-rule-for-judgment/ https://www.dannyguo.com/blog/my-seatbelt-rule-for-judgment/ https://www.psychologytoday.com/us/basics/dunning-kruger-effect https://www.psychologytoday.com/us/basics/dunning-kruger-eff... Edit: They can interfere with WiFi because a microwave could leak a tenth of a percent of its nameplate power and it would overpower your access point by anywhere from 1x to 10x. Access points can, on certain bands, have radios up to ~1W, but 125-250mW is much more common. It would also be completely harmless even if you were standing inches away from whatever the source of the leak was. Microwave RF energy only becomes dangerous when it is strong enough to heat up parts of your body that cannot cool themselves quickly due to having little/no bloodflow, like your eyes. You could put a parabolic antenna on your home wifi AP and standing in that beam would expose you to more RF energy than your microwave. I don't know why HN suddenly has a "DANGERS OF MICROWAVE OVENS!" boner this week...this is I think at least the second article on the subject of the 'dangers' of microwave ovens. Regarding "the door gap is a long line" - that would be relevant if the beam were aimed parallel (or close to parallel) with the gap...

Retric 5y ago
> The same reason the metal grid works is why there doesn't need to be a perfect door seal. As long as as the gap is smaller than the wavelength of the microwaves, it's fine. The issue is the gap in a door normally forms a long line. The fact they interfere with WiFi should make it obvious the average microwaves faraday cage is far from perfect.

jodrellblank 5y ago

> "I kind of doubt an independent inventor could bring this to market with today's startup climate." Especially the kind of inventor who created microwaves for experiments with reanimating frozen hamsters, cough James Lovelock. (Tom Scott's video "I promise this story about microwaves is interesting" which includes a brief interview with James Lovelock last year at age 101 - https://www.youtube.com/watch?v=2tdiKTSdE9Y https://www.youtube.com/watch?v=2tdiKTSdE9Y )