Transformers only apply to AC, where there is a fluctuating magnetic field.
A transformer in a DC circuit is just a physically large (very low resistance) resistor.
The standard practice to convert DC voltage (at least for these voltages) would be a buck converter, which is an active circuit. [1]
They're also using it for their humanoid robot
A standard I'd love to be modernized would be wider availability of 240 volt outlets in North America. I'd love to have the option of a 240 V electric kettle on my countertop or a 240 V toaster/pizza oven.
And while it might be safer on paper, in practice there is little difference in injury rates US vs UK.
Totally disagree on that injury rate though, and you would too if you ever stepped on a type G plug.
I actually think the US should start requiring those. Start with having 1 or 2 in the kitchen, and additionally 1 within 100 feet of any spot in the house.
Once they are more common we'll start to see appliances start using them. At first mainly for cooking and vacuum cleaners.
But if the NEMA 5-15 is a not-great standard, then the NEMA 6-20 is also equally-flawed. They've both got the same set of issues.
The only good reason for 6-20 (or 6-15) in American kitchens is that it is an "approved" connector. It fits in, today, with what we have here in the States in terms of broadly-accepted wiring methods, safety testing, and formal training. That is indeed a good reason, and I do not wish to diminish that reason.
If 6-20 were already commonly-used in residential environments -- anywhere -- then it'd be easy to say that it would be a nice thing to have in every kitchen. But it has neither momentum nor inertia, because it mostly just doesn't exist.
So if we're going to set out sights on what is ostensibly going to be considered a "new" plug, then: Why not aim for one that doesn't inherently suck?
The thing is people keep complaining about how bad NEMA 5 and 6 are - and yet, somehow, the US doesn't have a lot of electrical injuries. So it seems the theory doesn't match the reality. It's just not that big of a problem.
NEMA 5/6 sockets have a lot going for them: They are physically relatively small, the flat blade has a much better contact surface relative to round plugs, they are also much cheaper to make (both the plug and the socket).
I could certainly design something better - I would put all 3 prongs in a line (with un-even spacing to ensure polarity) to make the plug even smaller, and put an insulating sheath on the top of the prong designed exactly right so that when it makes electrical contact the metal part of the prong is no longer exposed.
Even better: You could make an outlet that is simultaneously 120V with backward compatibility and 240V! (And I just realized that polarity is pointless - 240V have a hot on both sides.) I'm starting to warm to your idea of a new outlet. Have three slots in a row.
> Why not aim for one that doesn't inherently suck?
Out of curiosity, other than the things I designed against, what other issues do you have with it?
I have issues with typical US socket arrangements. They begin to disconnect too easily when things move around, as small appliances in a kitchen tend to do. They still work when partially-disconnected, but they have exposed live elements in this state.
This has probably happened to me hundreds of times so far. And while it hasn't harmed me yet, and I'm not particularly afraid of 125VAC, I'm always aware of that potential harm when I encounter the condition. I have also found (and corrected) the mythological problem where a metal thing has slid down a wall and onto a partially-inserted plug.
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You know, as I wrote what I wrote before and I write this now, I've reviewed many of the world's plugs. Some seem kind of OK, some are huge for no apparent reason (adding both cost and bulk for little benefit), and some seem like a series of trade-offs that are based in legacy.
And the US certainly has its own legacies, too:
Like you alluded to, multi-speed 4-wire outlets, offering hot, hot, neutral, and ground. In a fairy tale world where these can be compatible with bog-standard NEMA 5-15P appliances, that becomes a very, very easy thing to sell. It becomes so easy to sell that the ease of use starts to become more important than some of the other functions I've considered. They can even configured so that each of the 120V portions operates on a separate leg. (This ruins global compatibility, and will ultimately require revision of the NEC since split-phase duplex outlets are presently only allowed in kitchens, but boy would that be easy to sell. It also requires 4 wires instead of 3.)
Is there enough room to add a contact (or two) inside of a 5-15R, using modern manufacturing methods? Maybe a square hole near the middle somewhere with positive engagement?
https://www.plugsocketmuseum.nl/
> They begin to disconnect too easily when things move around
Replace your outlets, the old ones did this, but the newer ones, especially commercial grade (which is only $2 more), hold much better and they won't go loose.
> Is there enough room to add a contact (or two) inside of a 5-15R
I was going to have it like:
-.
| | |
.-
The cord for the new 240V plug would exit from the left or right, instead of straight out or from the bottom like current cords.
This would make the plug long and narrow, and inline with the cord, to make it smaller.
I would have this outlet always be 20A, there's no reason to have this 15A stuff we have now - that's just legacy. But if we really needed to, the center slot could turn into a + shape to enable 15 vs 20.
A connector with a positive snap-action would seem better: It is either snapped tightly into place, where it is connected and it works. Or it is unsnapped, where it is electrically disconnected and free to fall out completely. USB C seems to get this part right, as an example; good versions of the C7 ("mickey mouse") power connector seen on many laptops and boomboxes of yore also seem to get at least part of it right.
Anyhow, I don't think it can happen with a new combined outlet that preserves 5-15P compabibility, so...
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Your combined outlet idea is neat, but it increases the minimum size by 50% and that increase may require new boxes, and definitely requires new coverplates.
I'm thinking something more like this arrangement:
| o |
U
The new terminal can be a blade, but a square or rectangular cross-section seems better: It's still flat for ease of making good contact, but it's also strong in more than one direction. Having a shape for that hole that is incompatible with existing blades also helps prevent Curious Little Jimmy from bodging a 5-15P into the wrong holes and torching appliances by applying twice their expected voltage.
It preserves 5-15P compatibility, does not necessarily increase the space used inside of a box, and fits behind the existing (and vast) array of cover plates. Grounding remains optional, and polarization and remains optional for non-grounded things (and both are determined by the plug end, not the outlet end, just as today).
The ground terminals always face the "outside", which is perhaps safer, and the inverted outlet
Still to sort:
Tamper resistance mechanism. The NEC requires that mechanism in many cases, these days, and universal application requires NEC compliance.
Also compatibility with existing wiring. One advantage of using a single-purpose outlet like 6-20R or even L6-20R is that existing wiring can (in some cases) be re-used by re-identifying (eg) the white wire for use as a hot leg, and this can speed adoption in some existing dwellings. But both of the layouts we've drawn have a neutral terminal on their face and invite the insertion of 120V plugs, even if they won't work.
Sure, but that's not what I'd call terribly energy efficient. I'd rather boil on demand seeing as my wife, the primary user of the kettle, doesn't drink tea while she's sleeping or at the office.
As far as the pizza oven goes I'll probably end up going with an propane Ooni, Roccbox, or the like on my patio.
I'm just saying that I'd like to option to dump 240V @ 13A into a small appliance in my kitchen. As it stands now I'm limited to a paltry 1500 watts compared to a peek that's more than double that in the UK.
I’m glad that Tesla is trying to do that with the 48V auxiliary (non-traction) battery. 48V is just below the Low Voltage threshold for human safety (NEC, NFPA). It’s also 4X the 12V std and still a number cleanly divisible by 3V.
Sometimes first principles design outshines industry standards especially when there are newer reasons.