I have a Warehouse with 8ft T12 light fittings. The expense of locating the bulbs or fitting T5 adaptors seems to be outweighed by replacing the light fitting itself. Do I need an NICEIC electrician to change the light fitting as it appears to be as simple as changing a plug?

OK, Yes competent persons, as above. Certification, perhaps, the work must comply with EAWR89, & PUWER98 at least. Easy way, comply with BS7671, certification, perhaps not if LIKE for LIKE maintenance. If not then definitely required. If like for like, then the essential safety tests under BS7671 are still required. If you have persons competent to do this then fine, if not, COMPETENT outside contractor it is.

Here we go again! My Risk Assessment is this: If you don't know the 17th, how to test and certify electrical work then keep your hands in your pockets and the mouth closed. Too many 'Fred knows a bit about about electrics' already. Kill yourself by all means but make an effort not to kill anyone else pleas! (sic)