i think the difference you're looking for is in volume of copper.
The big savings would be in longer lived electronic devices. A sizable portion of digital electronics ultimately fail because the capacitors in their power supplies exceed their designed lifetime. Electrolytic capacitors (ticking time bombs) are cheap and compact for the capacity so they are used for the energy storage required in single phase systems, but if designing a three phase power supply less storage is required and maybe manufacturers wouldn't have to optimize the smaller, capacitors with electrolytics. I've had a 4k TV and a rather expensive musical instrument amp fail for capacitors this year, about $3000 of gear there. Looking back further there are a couple of professional powered sound reinforcement speakers (twice), an iMac G5 (three times). It's probably safe to say over the decades I've had $10k of electronics fail prematurely from electrolytic capacitor failure. These are all items which were not obsolete or worn out. Scale that up from one person to worldwide and it's easily in the hundreds of billions (10⁹) of dollars which could be saved.
The problem is you can't get there from where we are. No one wants to drag more wires to residential houses, no one wants to shell out >$1k for a household phase converter and then rewire their house. You won't convince people to add three phase to a new house because it might be the future. And you won't convince the semiconductor houses to make a line of three phase power supply controller chips just because, well, maybe someone might use it.
We're probably trapped at a suboptimal local maximum.
Edit: In response to atoav's comment I found IEC 60309 and its extra low voltage variant which is a 42mm (1 2.3") 3 phase plug and connector in two compatible sizes good for 1.3kW and 2.6kW. Also, that Germans and Swedes did the engineering first and then built an electrical system and they get 480V 3 phase at 16A to their cooktops and stoves through a plug for a whopping 13kW!
Edit: and as an aside, why we probably don't do that everywhere: it makes for bigger plugs, and keeping safety standards can be a bit more expensive and space intensive with the potential 400V between phases.
I see the successor to the 16A Perilex connectors you are referencing is IEC 60309 which has an "extra low voltage" version with a smaller, 42mm diameter (1 2/3") plug good for 16A or 32A. 16A devices will fit in a 32A socket, but not the other way around. So that seems to be a 1.3kW and 2.6kW solution. Sign me up!
Germany is 230v so that would be more like 3kw and 6kw.
I'm in the UK (also 230v) and a standard outlet can do 3kw, I think fuseboard fuses are 32amp so I don't know if 6kw is a practical upper bound though (edit: On 2nd thoughts I'm not even sure this is relevant to 3 phase).
Modern single ovens can also be connected to a standard single phase outlet rather than a dedicated circuit. In my kitchen the induction cooktop is on a 16A three phase circuit, and all the other outlets (fridge/freezer, oven, dishwasher and appliances) are on a 16A single phase circuit.
5:11 from 20°C to 220°C
I've never actually come across anything higher than 3kw, also a 16amp fuse isnt that precise, you could probably get up to 20 amps without it failing. The hotter you run it the quicker it fails though, so if you're regularly running 3.7kw through a 16 amp fuse, you may well find it failing, not through an underlying fault of anything plugged in to it.
Most cables are 16A, so the outlets are 16A as well. Also UK uses 240V, not 230V. 32A circuit breakers would make the cables burn when overloaded.
"Use a 30amp fuse or 32amp MCB for larger radial circuits, ring circuits up to 100m, cookers and electric showers up to 7200W"
>ring circuits up to 100m, cookers and electric showers up to 7200W
Normally those tend to be 3phases.
Of course it's possible to get over 16A on a single phase and a circuit breaker but that's quite a non-standard option. The issue is that if the fuse/circuit breaker is rated for 32A in a standard application (i.e. an outlet) the cables are likely to burn 1st.
I'm talking about the UK here, which I understood to be similar to the rest of Europe(?).
That's a UK website and 3 phase isn't common here. I've just double checked my fuse box, and I have a 32 amp fuse for my socket ring main.
Don't forget for a ring main the current is spread over 2 wires, so if theres 32amps power draw, theres only 16amp on each side of the ring.
We don't have three phase (well its not common) but we can heat an oven up to 220c(420f) in 7 minutes. I think its a 3kw oven. its on a 32 amp (isolated) breaker.
All we are missing is for it to be standard to wire the 3 phase distribution throughout buildings to every outlet (preferably in a backwards compatible manner; in theory converting 3-phase to single phase is just a matter of ignoring a wire. I would assume that a) the grid can handle people doing this and b) doing this with out current 3-phase standard would result in our current single phase standard,
While the appliances are probably approved fo 208V, I doubt they’re drawing more peak current to make up for it.
Or make power supplies some sort of standard, so you can use your own expensive capacitor power supply instead? Or just shop for things that have separated power supplies?
So as its going to become AC at some point anyway, why not use the existing wiring.