Exactly what he said ... That's what I was getting at.
There seem to be lots of confusion so my reply was more adding info that may help some people than aimed specifically at you.
As for what i know that 220-240v 40a are 3 wires plug and cable, which are 2 hot wire and 1 ground wire. Each hot wire are still only 20a.
15a or 20a are normal outlet in most home in the US, which can hanle 1800/2400w. I will reserve 20% of the load for safety due to if you are running the power consistently over 3 hours. so you are talking about 1440/1920w per a breaker line (not each outlet).
With your kitchen 240v that really don't give you much if you running a 6-8gpu rig 1k-1.2kw. which only allow you run 2 rigs or 3 max. BTW most American home power line are 100a cable from outside, apartment that depend could be 100 or 200a. you really can't setup like mining farm, because you will max out your power line after 4 rigs that take 1kw+ each system. Unless you not using any electricity at home, like Microwave, AC, Ranger, Fridge bla bla bla that draw power as well.
No. While 240v 40a is 3 or 4 wires, both hots are 40A, but at 120v, the ground and optionally the neutral are there but not any different from usual. Two 120v 20a give you 240v 20a, not 40a. Phil is correct as usual.
This is incorrect. 240V is 2 hot and a bonded conductor, commonly called the ground. There is no neutral.
A 4 wire system is 3 phase - 2 hot, 1 neutral, 1 bonded conductor (ground). Commonly used in commercial buildings, not typical for residential. Due to 3 phases, you get the standard 120V phase to ground (or neutral) and 208V phase to phase.
Hold on a second. What is incorrect, to me you just repeated what i said. Except though i believe you are incorrect about the 3 phase bit.
Are you arguing the neutral part? That's only useful if you want 120V. It's not 3 phase, that's something else. 3 Phase is not available in residential setup, but 4 wire 240v is. It's standard even, you will see 4 pins on oven connector, as such is the case in this thread; 2 Hot, 1 Ground, 1 Neutral
For example a lot of ovens have a 120V plug in the front, that's because the 120V will use 1 hot leg + neutral as reference.
Then the 240V use 2 120V hot leg. Both 120V and 240V has a ground, whether you use it or not.
Efficiency to a degree is valid, yes, though in my house I've noticed an extremely negligible difference when testing antminer PSUs (though they are SUPPOSED to have significant efficiency variance).
Draw? 4x120=480W. 2x240=480W. How are you running double the rigs on the same wattage?
You're able to run more on less amp draw with 240. Not more wattage. Maybe I said that wrong. If you have 100amp service, that's your limit. If you have 200amp service, that's your limit ...
I see what you're saying, but the draw is coming from the single breaker in the main box, so it has no effect on your service limit. From that point, a 220 40a will provide enough power for 2x20a @220 or 4x20a @110. It's the same amount of energy.
I'm pretty sure that's not right, if you use 120V you will be using 1 Hot leg + 1 Neutral. You won't be using both hot legs. So if you have 4 * 20A 120V breaker you have 80A available, 80% = 64A@120V = 7680Watts available. If you have 80A on 240V you have 64A@240V = 15360Watts available.
This is why you want to use 240V for mining, as you halve your amount of AMP use, effectively having access to twice as much Watts on the same electrical entrance.
Maybe a certified Electrician can comment...