First of all, I am not sure of your demand to use 220. Think of 220 as having double the juice, because you have two "hot legs", in other words, each leg carries 110v. Theoretically, (and I am no electrician) One 110v, 15 amp breaker for each power supply will do the job, and for overkill you can use 12 ga. wire.....or minimum 50 amp 220v, I would think for only 16 feet 10, maybe 8 ga.

Another thought would be, 'gee I want to save space in the breaker box.' Then, you can use one 60 amp 220v breaker, bring the 8 ga. to a sub panel, break it to 110v and put 15 amp breakers in the sub panel and feed your four power supplies either hard wired, or (preferably) with 15amp rated plugs. The 8 ga. needs to be the type with 3 conductors plus ground to be safest and in 'code'.

There are many ways to do this, but safety and redunancy is important. If you do not know what you are doing get someone who does, because high amperage will start a fire or kill if you screw up.