5 ms·

> It's totally possible to deliver 3kw in the form factor of USBC safely Wouldnt that take like 400V? Not sure how safe that would be.

by ac29 4y ago

londons_explore 4y ago
And 10,000 volts build up on your body when you rub a balloon on your head... With high voltages, it's all down to how many joules you allow to be dissipated in a human. Ie. Current*voltage*time. Specifically, anything over about 0.01 Joules is dangerous. To use high voltages in a consumer product you need to limit either the current or the time, and you need to do it in a way that is very robust to being chewed on by a baby in a bath. And it needs to be robust to that even when built by a corner-cutting factory. One approach to that is to have either end of the link 'test' the other end - ie. Simulate a human touching the wire. If power isn't turned off fast enough to be in spec, then the remote end or cable isn't working correctly and shouldnt be used.
Dalewyn 4y ago
Wattage is a product of voltage and amperage, so the question would be what the voltage supply is (either 100~120V or 200~240V depending on region) and how much amperage the cable and connections can handle. To supply 3000W with a 110V supply would require around 28A, which will trip any 10A or 15A breaker commonly found on most house lines going to electrical outlets, but it's well within the realm of something that could be supplied by a circuit equipped with a 30A or higher breaker and qualified wiring. Of course at 30A or higher, we're talking about things that connect via those bulky connectors you would find on dryers and other high load electronics. Bulky for your safety, mind you.
- mschuster91 4y ago
  > To supply 3000W with a 110V supply would require around 28A, which will trip any 10A or 15A breaker commonly found on most house lines going to electrical outlets The utter, utter majority of the world runs on something around ~230V [1], except America and Japan. [1] https://en.wikipedia.org/wiki/Mains_electricity_by_country#/media/File:World_Map_of_Mains_Voltages_and_Frequencies,_Detailed.svg https://en.wikipedia.org/wiki/Mains_electricity_by_country#/...
  - throw0101c 4y ago
    The US (and CA) runs on 240V as well, it's just split in half for smaller appliances. See requisite Technology Connections video: * https://www.youtube.com/watch?v=jMmUoZh3Hq4 https://www.youtube.com/watch?v=jMmUoZh3Hq4 My stove and clothes dryer are certainly not 120V.
    - tjoff 4y ago
      In the same way that 240V countries run on 400V as well then?
      - Kirby64 4y ago
        Sort of. Outside of industrial or businesses, my understanding is that it is rare to see multi-phase power (400V) used in power applications. You may get 3 phases into your house, but the phases are used separately (each at 240V) for most things in residential.
        tjoff 4y ago
        Stoves are pretty much always at three phases unless it is something like a small summer-house Washing machines too I've heard.
      - deleted 4y ago
        [deleted]
xattt 4y ago
48V is the max dry “skin” safe voltage that won’t cause a shock.
hnuser123456 4y ago
Did some napkin math for fun. There are 12 contacts spaced within 6mm inside a USB-C cable, on each side. Assuming each contact is 0.25mm wide with a 0.25mm gap between each, it would only take somewhere around 1000V to simply arc through the air between contacts. And anything over 5 amps is going to start causing resistive heating simply due to how small and thin the wires and contacts are. So maybe, if you built it and tuned it really well, you could push up to around 5kW through a USB-C, with it being on the brink of shorting itself out and/or melting itself.

> It's totally possible to deliver 3kw in the form factor of USBC safely Wouldnt that take like 400V? Not sure how safe that would be.

by ac29 4y ago

> It's totally possible to deliver 3kw in the form factor of USBC safely Wouldnt that take like 400V? Not sure how safe that would be.

londons_explore 4y ago

And 10,000 volts build up on your body when you rub a balloon on your head... With high voltages, it's all down to how many joules you allow to be dissipated in a human. Ie. Current*voltage*time. Specifically, anything over about 0.01 Joules is dangerous. To use high voltages in a consumer product you need to limit either the current or the time, and you need to do it in a way that is very robust to being chewed on by a baby in a bath. And it needs to be robust to that even when built by a corner-cutting factory. One approach to that is to have either end of the link 'test' the other end - ie. Simulate a human touching the wire. If power isn't turned off fast enough to be in spec, then the remote end or cable isn't working correctly and shouldnt be used.

Dalewyn 4y ago

Wattage is a product of voltage and amperage, so the question would be what the voltage supply is (either 100~120V or 200~240V depending on region) and how much amperage the cable and connections can handle. To supply 3000W with a 110V supply would require around 28A, which will trip any 10A or 15A breaker commonly found on most house lines going to electrical outlets, but it's well within the realm of something that could be supplied by a circuit equipped with a 30A or higher breaker and qualified wiring. Of course at 30A or higher, we're talking about things that connect via those bulky connectors you would find on dryers and other high load electronics. Bulky for your safety, mind you.

mschuster91 4y ago
> To supply 3000W with a 110V supply would require around 28A, which will trip any 10A or 15A breaker commonly found on most house lines going to electrical outlets The utter, utter majority of the world runs on something around ~230V [1], except America and Japan. [1] https://en.wikipedia.org/wiki/Mains_electricity_by_country#/media/File:World_Map_of_Mains_Voltages_and_Frequencies,_Detailed.svg https://en.wikipedia.org/wiki/Mains_electricity_by_country#/...
- throw0101c 4y ago
  The US (and CA) runs on 240V as well, it's just split in half for smaller appliances. See requisite Technology Connections video: * https://www.youtube.com/watch?v=jMmUoZh3Hq4 https://www.youtube.com/watch?v=jMmUoZh3Hq4 My stove and clothes dryer are certainly not 120V.
  - tjoff 4y ago
    In the same way that 240V countries run on 400V as well then?
    - Kirby64 4y ago
      Sort of. Outside of industrial or businesses, my understanding is that it is rare to see multi-phase power (400V) used in power applications. You may get 3 phases into your house, but the phases are used separately (each at 240V) for most things in residential.
      - tjoff 4y ago
        Stoves are pretty much always at three phases unless it is something like a small summer-house Washing machines too I've heard.
    - deleted 4y ago
      [deleted]

xattt 4y ago

48V is the max dry “skin” safe voltage that won’t cause a shock.

hnuser123456 4y ago

Did some napkin math for fun. There are 12 contacts spaced within 6mm inside a USB-C cable, on each side. Assuming each contact is 0.25mm wide with a 0.25mm gap between each, it would only take somewhere around 1000V to simply arc through the air between contacts. And anything over 5 amps is going to start causing resistive heating simply due to how small and thin the wires and contacts are. So maybe, if you built it and tuned it really well, you could push up to around 5kW through a USB-C, with it being on the brink of shorting itself out and/or melting itself.