A bunch of things not adding up here.
First, 1200W is fine on a typical residential circuit: in both the US and Canada (AFAIK) they're typically rated for 15A @ 120V, or 1800W (you can verify this by looking at the breaker in the panel). Many, many high-wattage consumer appliances are 1500W -- space heaters, microwave ovens, electric kettles -- and work fine on such circuits. So a 1200W PSU shouldn't be any kind of problem (provided you don't have any other significant loads on that circuit, obviously). The guy at the computer store (Future Shop by any chance?) clearly doesn't know what he's talking about.
But I don't know what your friend is talking about either. Even with a 1200W PSU, how exactly is he intending to power 14 PCIe cards? They expect to draw some of their power from the PCIe lanes themselves, and no matter what kind of "riser" arrangement he might have that's going to be problematic. Equally problematic is bandwidth, because pretty much all chipsets top out in the ~22 lane range so most of those cards are going to end up with no more than PCIe 1x bandwidth to memory which very easily will bottleneck many HPC loads (at least the ones worth throwing 14 GPUs at), though for many datasets he's going to be bottlenecked by storage as well. Is he trying to crack encryption or something? At any rate I assume he's intending to do some kind of HPC / GPGPU application, since such a setup is pointless for graphics. And if he is doing some kind of ghetto HPC, why is using ATI cards (this is what Fermi/Tesla is for)? And how is he intending to cool this setup?