About 2400 watts on a standard 20amp breaker. Of course, anybody who's serious about putting in a mining farm isn't going to just plug their shit into a standard outlet and walk away.
Well....
Actually that was the plan of a couple of MiniRig owners. Go read up on the BFL forum.
Now that the specs are all over the place, that idea is toast.
Residential power can easily throw down 200a @240v. or 48,000 watts, or enough to run 1600 jalapenos @30watts. There's literally ZERO chance of anybody over-drawing residential power with BFL equipment.
I take it you are new to the concept of electrical nodes. Seriously, there is no way to utilize that much power....safely...with 24/7/365 operation.
Residential power is to be used while living. Having something drawing that amount of dangerous load 24x7 is unusual and unsafe. Your wires on a hot day would probably catch fire. I have 173 amps installed in my home. I use my home for "other things" than simply a wooden [flammable] structure to house my mining device.

It could be said that the Minirig is now incompatible with residential power.
And before you tout 240V. Keep in mind that those are usually reserved for 1 outlet or maybe 2 per residence. Keeping 8KW+~10KW+ on a 240V plug is not safe. Even if you divide it into two units. More than 2 units and you won't find many (or any) normal residences that have that many outlets rated at 240V. (In the USA)
If you're talking about their 1500Gh units, even if you assume 5watts/Gh that's still only 62.5 amps. Plenty of residential hot tubs drawing WAY more than that...
Again, you are mixing a dedicated installation with appropriate safety (implied) with that of a mining unit that will consume almost an entire households electrical box.
Could you pull it off? Probably.
Would it be practical...unlikely.
Would it be safe for 24x7/365 operation...hell no.
Valid points, mostly. However, first I have to correct my math. I calculated the amperage for 110v power, so if we are figuring 240v power, it's actually only 31.25aps.
However, a 100 amp fuse should be fine to run a 62.5 amp device, even if that were the case, round the clock. If there are people planning on buying multiple devices @$30,000/pop and running them on residential power, that's a fallacy on the part of those individuals, and not the fault of BFL. For one, they're not even listing it as available, but anybody planning on putting multiple machines like that on a residential service main is seriously failing at logic.
These machines (though they're not even available for presale at this time) assuming a high power consumption or not, are intended for commercial-grade installations. People with that kind of cash to throw at mining rigs have dedicated, air-conditioned server rooms, powered by industrial-grade electrical wiring systems, with battery backup systems, backed up by generators, etc.
If you've got $30,000 to drop per machine, on a few machines, you've got the money to put it in a proper home. That means leasing a small amount of dedicated space in a datacenter.
If you're just going to buy one, you can get away with running it at your home, but you're gonna have to consider its power consumption needs, and possibly hire an electrician to put in a dedicated circuit for you (again, if you've got $30k, you can afford to have this done).
If people are planning on hooking it up in their college dorm room, they probably need to consider a different approach.
But none of this has anything to do with whether BFL should actually move forward with the project or not.