In the US residential and non-industrial is usually split phase. We have a single phase coming in, but its got a half tap at the service transformer for 120V nominal which is what most small to medium devices are designed to work with. The 120V device can be wire from either leg to the half tap or neutral. It makes for some interesting conversations with other do-it-yourselfers. In the past there were house which only received half phase. That is their service entrance was 120V nominal only.
I may not have the terms exactly right, but that's the gist of it. Like I said, it makes wiring in extra stuff interesting.
------------------------- I remember the single drop and 60A screw-in fusebox. My father bought and remodeled old houses as a sideline, I think because it gave him problems he could solve with a hammer. He became pretty good at everything except 3-way light switches. I might have helped him more if my role hadn't been the nail.
I would describe the US residential service as coming from a center-tapped transformer secondary winding with the center tap defined as neutral and grounded, thus the two ends of the secondary are 120V at 180 degrees apart, each is 120V to neutral and 240V to the other one. In the breaker box the connecting tabs to the two hot "phases" are interleaved such that a double breaker connects to both for 240V, a single breaker to one for 120V, and the single breakers above and below it are the opposite phase so hopefully the electrician will more or less balance the loads between them as he works his way down.
Large loads such as the kitchen stove, water heater and clothes dryer use double breakers for 240V, wall outlets and room overhead lighting uses single ones for 120V, with the loads connected in series unlike the British loop that feeds from both ends. The wall outlets and switched ceiling lighting in each room are supposed to be on different breakers so the room can be lit with one while the other is shut off for maintenance. Back when I learned this the wall outlet circuits were wired for 20A and the lighting for 15A, with thinner wire. Sometimes a wall switch controls an outlet meant for a lamp, especially if there isn't an overhead ceiling lamp which could cause a leak in the insulation.
There can be variations. My house has a separate meter and breaker box for the water heater which is billed at a lower rate. The main drop is 200A for the baseboard electric heating that was expected to be cheap nuclear in
1970. Rooftop solar uses a different meter that records power bought and sold by the customer separately. Determining the direction of AC is actually easy, a phone does it with voice to send and receive on a single pair of wires.
Another difference from British practice is the fuse isn't in the plug, unless it's a built-in ground fault interrupter. It protects the house wiring, the appliance is its designers problem. Old fuse boxes were meant to have the center contact of the screw-in fuse hot so that once you unscrewed the fuse part way the more accessible threaded shell was safe to accidentally touch, which it wouldn't be with a ring main. Holders for cylindrical glass automotive fuses that can be used for 120V should be wired the same way, hot at the inner end.
You can identify which breaker controls an outlet without a helper by plugging in a vacuum cleaner that vibrates the floor and can be heard from far away.
Although house wiring is sometimes considered two phase, that term is formally reserved for separate circuits 90 degrees apart which was Tesla's original sine and cosine supply that created a smoothly rotating magnetic field to eliminate DC motor brushes. It required four distribution wires while 3 phases at 120 degrees apart could be done more cheaply with three and so replaced it.
Industrial schematics label the phases and the wires themselves L1, L2 and L3 (L=Line) ,and each succeeding wire connection takes an increasing numerical prefix, so that the wires coming from the 3 phase breaker may be
1L1, 1L2, 1L3, then 2L1, 2L2, 2L3 from a contactor to a motor, etc. The parallel lines that look like a capacitor are normally open relay contacts that should have their associated Control Relay (CR) indicated with a circle for the coil. The N-like variant is a normally closed contact, normally meaning powered off. This is called a ladder diagram because the power lines are usually vertical and the relay contacts and coils etc drawn horizontally between them.
-jsw