That prison looked a lot like the old Ohio Penitentiary in downtown Columbus that dated from the 1860’s, so the systems in that prison could have been very outdated and not up to code. Remember the warden stating that the state legislator didn’t give a damn about spending money on prisons and it wouldn’t surprise to find that big government systems like prisons didn’t get updated or required to meet new codes. Hell, they may have even taken the money for upgrades and keep it for themselves; this was Shawshank’s management philosophy MO after all.