OHIO
Code version enforced in Ohio depends on each projects application for plan review date [your approved plans might have a building department received date, that's what you're looking for]. . Plan review approval date or permit date doesn't matter.
The state took over code decision control from local municipalities on May 27, 2007. . Zoning remains under local control and fire codes can have local fire department/marshall amendments or requirements. . But building code is now state only.
May '07 thru Dec '07, residential* - '05 NEC
May '07 thru Dec '07, commercial* - '05 NEC
Jan '08 thru March '08, residential* - '08 NEC
Jan '08 thru March '08, commercial* - '08 NEC
April '08 thru June '08, residential* - '05 NEC
April '08 thru June '08, commercial* - '08 NEC
July '08 thru Dec '08, residential* - ??**
July '08 thru Dec '08, commercial* - '08 NEC
Jan '09 onward, residential* - '08 NEC [verbally stated by the OBBS, but not on paper yet]
Jan '09 onward, commercial* - '08 NEC
residential* = 1,2,+3 family residential
commercial* = all nondwelling + 4 or more family residential
??** = the Governors emergency order covered April thru June. . OBBS will pick up after June with their rulings. . It appears they will stay with '05 until after Oct 1 when the new Commerce Department electrical code committee will make their recommendation on or before that date. . I'm betting that we're staying with the '05 for 1,2,+3 family thru Dec 31.