Like I said in my zombie plan, I intend on occupying a school and using that as a center of expansion for the new township that would be built. But for an initial shelter I don't see it doing that well. Zombie Apocalypse, I doubt that the electricity and the water would continue to run; not because machines stop at plants but just because of human error like someone running into a power line or a squirrel chewing through one (I've seen both happen before).
My plan is based off that, that when the proverbial shit hits the fan that all major sources of power will go out, water will stop running, and I'll be back to using candle light.
power and water going out should be a given during a zombie apocalypse, unless you are holed up in some kinda self sufficient military base, and even then problems might happen. Im not so certain that any power source would run forever though, unless wherever you are holed up runs on solar power and not a lot of places have those. Most likely places where you would find shelter at run on some kinda fossil fuel generator and as soon as you are out of fuel then its over, powerwise anyway.
The first thing id do though is to make sure that once my area is secure, i could have some way to purify water without electricity, as well as to be able to grow my own food. Given enough time i think both could possibly be done at a school, but you would have to have done some preparation before hand, to have access to the tools to make this possible.
Cause once the zombies come, your probably not gona be able to shop at your nearest home depot without running into problems, if not bitten outright while wandering through the store and lugging heavy objects around.