There seem to be lots of confusion so my reply was more adding info that may help some people than aimed specifically at you.
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.
I am more then 90% of the time. But In this case I am really sure he should do what I said.