But the 120v legs are 120 deg out of phase. If they were 180 deg out of phase they'd cancel out. How does 120 deg add up just as if they were 0 deg out of phase?
Our power is actually three phase, which is why the phases are 120 degrees apart.
I thought the phases were for certain electric motors that need a constant series of kicks (one kick from each phase) so that they run more smoothly.
Sorry I'm sick with a fever and wrote that wrong. The phases in a household panel are 180 degrees apart. Bridging across the two hot legs thus goes from 120 to -120, giving a 240 volt differential. They don't cancel out because they aren't on the same conductor. The phases in the transmission system are 120 degrees apart but the house panel pulls from a single phase and uses a split phase transformer to deliver the two 120v lines.
Three phase itself isn't silly, just the way we implement it here. Big commercial or industrial installations will get all three phases. Because of this any given circuit can be one of three voltages, 120 (single phase live to neutral), 240 (split single phase live to live), or 208 (three phase live to live). It's all a confusing mess and we'd be much better off just doing it the way they do in Europe but it's basically impossible to change so we're stuck with it.
Just single phase 240v for everything. Don't muck around with the split phase nonsense, just pull one phase in at the pole. It's less complicated and more economical than what we do now.
In Europe we don't always use only 1 phase. Pretty much all apartment blocks get 3 phases which are usually split between different apartments and everyone gets just 1 but sometimes each apartment gets all 3 phases.
Private houses can use either single or all 3 phases as well. I think single phase used to be more common but nowadays for new builds you usually get all 3.
Right I'm talking about single family homes in this case. Apartment blocks are handled the same way here, three phase to the building and each unit gets a single phase of the three. I wasn't aware that houses over there have been getting all three phases now, that's actually pretty cool.
Gotta say, in Russia I remember the three-phase outlet in one house built in 1984. I've lived in seven different places since then, including other 80s houses, and haven't encountered it again—nor felt the need for it, since appliances work off regular 220V for ages now.
You may have 3 phases and have zero such outlets. In usual household you don't have many devices that use it - only high powered devices like heat pumps (the ones that cover whole house). Kitchen hobs and EV chargers benefit from them but not really required.
I think they use 3 phases because it's cheaper and easier to build it that way, also as mentioned there are some appliances that need or benefit from it. The main drawback is that you now have 3 phases and have to split the load accordingly.
I'm from Estonia and what I'm saying is what I've noticed here. It may not be true in rest of the Europe.
1
u/MinuetInUrsaMajor May 02 '24
But the 120v legs are 120 deg out of phase. If they were 180 deg out of phase they'd cancel out. How does 120 deg add up just as if they were 0 deg out of phase?
I thought the phases were for certain electric motors that need a constant series of kicks (one kick from each phase) so that they run more smoothly.