There has to be a comprimise somewhere along the line, parts of the US use 110v/220v split phase system with the 220v used for larger appliances.
Not just
parts of the U.S. 120/240V (as it is now specified) 1-phase 3-wire services have been the norm for residential supplies across the whole country for decades. You can still find a few 120V 2-wire services, but they are quite old now.
240vac @ 50Hz for most of the UK was fixed as we started on the national grid which was around 1960's with the national grid we transmitted power further than USA where they were powered at that time town by town.
The National Grid had a huge expansion in the 1960s, with 275 & 400kV long-distance transmission lines being built to increase capacity from the original 132kV systems, but the National Grid itself started much earlier, in the 1920s/30s.
And it's not true to say that American towns were powered individually. Vast transmission and distribution networks existed across the nation in the 1960s. They had developed along regional lines, due in part to the geography and demographics of the continent, and it's true that even today there is limited interconnection between different regional grids, but of course we're talking about a vast country compared to Britain, so a regional grid in North America can cover a far greater area than the entire U.K. National Grid. There are plenty of cross-border grids between the U.S. & Canada too.
There was a famous blackout in November 1965, when a tripped breaker and heavy demand led to an unfortunate cascade effect as loads were transferred to other lines, more breakers tripped, etc., until millions of homes were left without power across a wide area from Ontario to New Jersey and New England.
USA still have 220vac into each house with one leg upstairs and one leg down stairs and both to the cooker.
It would be rare to find a simple upstairs/downstairs split. The circuits are just shared between the two "hot" legs to distribute the load as evenly as possible. The two 20A small-appliance branch circuits which are specified for the kitchen & dining areas, for example, will often be on opposite legs of the service. It's also quite common to find a 3-wire circuit to a split-wired duplex receptacle where two medium to heavy loads are expected to be used. A duplex outlet under a worktop for a dishwasher and garbage disposal is a typical case.
New York still had DC supplies in 2000 mainly for lifts
2-phase 4-wire A.C. supplies were also still in use to some buildings until recently.
But in this country most industrial premises have same voltage as domestic but in USA 550vac and 660vac is common in industrial premises even here mines and quarries often use the higher voltages.
Most new commercial 3-phase services in the U.S. now are supplied as 120/208V or 277/480V Y systems. But there is a huge established base of delta services still in use, generally 240 or 480V.
Canada uses 120/208 the same as the U.S., but for heavier applications favors 347/600V systems instead of 277/480V. In both cases the Y system voltages were set so that phase-to-phase voltages matched the existing 480V and 600V delta systems.
But in USA they have still quite a few different systems running at the same time. The "Hot Wire" method of earthing delta secondary on transformers is something we never see here and I hope we never do.
I assume you're referring to the 4-wire delta arrangement, which is also known variously as high-leg delta, wild-leg delta, bastard-leg delta, red-leg delta, etc. It seems a little odd at first from a British perspective, but it was a neat method for allowing small 120V loads to be run alongside 240V delta without the need for extra on-site transformers or a separate 120/240V 1-ph 3-w service.
our street is supplied in banks of 4 or 5 houses.
theres 3 phase supply under the pavement. every 4 or 5 homes takes a single phase from this and its daisy chained to the 4/5 homes. Not directly through cutouts, but around the outsides of homes with spurs off. All done in concentric / seperate twin / combined twin oval cables.
terrace homes are often done in pairs, as the supply is under the stairs and two staircases will be side by side. Or the supply is next to the bay window in the lounge, as is next doors etc.
In rural and semi-rural areas you can find all sorts of different arrangements, as convenience often dictates the phasing, subject to maintaining an overall balance. In my road, for example, my house plus a couple on either side are on red phase, while several houses either side of those are mixed between red & blue. Then there's a whole row of homes on the opposite side of the road on yellow phase.
In some older parts of British towns you'll find that a side street has only two of the three phases along it. It's where the area was originally on a 3-wire D.C. system, and rather than replace every cable during the conversion to A.C., the electricity board simply tapped the existing feeders for each street into the new 3-phase distribution cable, so that one street is on red & yellow phases, the next on red & blue, the next on yellow & blue, etc.
Not like many of the older units which had double-pole fuses immediately accessible just inside the top cover. Of course, many of the units now are sealed internally with epoxy compound, so that wouldn't be possible!
