The voltage doesn't matter...
There are usually 15 and 20 amp circuits... 15a = 1800w 20a = 2400w
This machine will probably trip a 20a circuit... If I end up getting one I will have to use one plug from two circuits
Voltage matters (higher efficiency and more stable power). Its not just about the amps. I recently had my house updated to 300A total due to a recent fire caused by all my mining gears (overloaded the main meter) and I had six 20A breakers installed just for mining.
The SP30's come with two server PSU's, so you can split them between two circuits, but the voltage has a big impact. You can check the SP10 threads, no one on 110v get's anywhere near 1.4TH/s. I believe the highest I remember reading about was 1.3TH/s, and that was with someone blasting the a/c right in the intake fans to keep everything very cool and stabilize the voltage so some doesn't get lost as heat, and with a lot of fiddling around with the settings.
EDIT:
Also, you should never max out your circuit breakers. Treat a 20A breaker as a 18A breaker. It's best to leave at least 10% headroom.
So it would be more like 18A * 110v = 1980w per circuit. The SP30's have two 1200w PSU's, presumably pulling 1300w each (they advertise 2500w total, I highly doubt that). So as long as you split between two different circuits, the amperage won't be an issue, but the voltage still will be.
In hindsight, I wish I had those guys install at least two 220v lines, I regret that -_-' It would've only cost me about $75 more at that time, now I would have to pay about $800 to have everything redone.
The first versions of the SP10 firmware limited the PSUs to 1100 watts on 110V power. I own an SP10, May batch slow corner and I get a consistent 1.4TH/s out of it with the 1.5.2 firmware, and the tweak to remove the limiting of the PSU. Believe me, I would love to have gotten one of the earlier ones that got anywhere from 1.5 - 1.6TH/s, but no such luck.
As for the SP30, if I do end up purchasing one, it's going to be hosted. I've got a full breaker box, so if I wanted to get more power, I'd have to get the entire thing redone, and up my service from 200A to 300A, and then put in a few extra 240V/30A circuits and the Nema outlets. Way more than I'm willing to invest for my mining gear. Maybe in the future I'll consider it, but for now...
EDIT: By the way, bitmadrid, it's the 15th. What's the final price you've negotiated?