Hacker News Reader

Comment by mschuster91 | Hacker News Reader

You're talking in Euros... we have 230V power, while Americans and a few other holdouts still use 110V. The problem is, the lower the voltage the more current you need - an 1 kW vacuum draws 9 amps in the US, but 4.5 in Europe.

The unit of billing - kW/h - however remains the same.

View on HN

This sounds plausible but is subtly incorrect: the US uses split phase power and 100A means 100A on each of the two legs (+/-120V). So if you balance the legs correctly, you can get 240V*100A on 100A service. This is important for example for car charging where both legs are used and balanced.

America is 120v now, I believe - and many houses have a centre-tapped neutral supply [1] which means they actually can have 240v outlets in garages, workshops, utility rooms (etc) for high power devices.

[1] https://electronics.stackexchange.com/questions/487836/how-d...

So this is different from a 3 phase system (N L1 L2 L3) with 120 degrees shift between the lines? It is instead basically a 2 phase system N L1 L2 with a 180 degree phase shift between L1 and L2?

I was already confused with the 240 being mentioned somewhere in this thread... it becomes a bit clearer now.

Not an electrician, but yes (I think).

https://en.wikipedia.org/wiki/Split-phase_electric_power

Most US residential housing is fed off a 240V center tapped transformer. Center tap is connected to ground and neutral at the breaker panel. That gives you two 120V phases to neutral. And 240V from phase to phase.

In the breaker panels the phase alternates as you go down the rows of breakers. So you can install a dual breaker for 240V. Typically only large appliances like stoves, water heater, driers, and air conditioners are 240V. Everything else is 120V.

I heartily recommend a three phase induction stove. 400V of cooking power (mine is rated at something like 8kW…?). Carbon steel pans get ready in seconds.

Reply on news.ycombinator.com