250.22 says it shall not be grounded when serving areas with hazardous anesthizing equipment, 517.61.
517.20 says areas in wet locations shall be either gfi or served by an isolated power system. If the OR is considered a wet location is up to the hospital, but that is usually why they use isolation panels since most anesthizing agents aren't explosive anymore. Wet locations may also pertain to ICU or Trauma rooms depending on how the hospital classifies it. I have seen hopitals dedicate a couple of ICU's as wet location and the rest as not so save money.
