According to NEC 2014, Section 410.130(G)(1), fluorescent luminaires with ballasts are required to have a disconnecting means either internal or external to each luminaire.
How about when the ballast is unwired (or removed) in order to install self-driven LED tubes, in which the 120v (or 277v) branch circuit is wired directly to the socket on one end of the fixture?
Should this be a code requirement, or not?
I think this requirement was put in to address the changing out of ballasts, so you did not need to turn off the switch/breaker feeding the whole row of recessed trouffers. I think that there may be a need to disconnect the incoming power if a socket goes bad, but not necessarily when a tube goes bad, so the same thinking should apply.
The irony is that the NEC is pressing the installation of disconnecting means at a time when it will be decades between service calls.
IMHO, the Code should discourage 480VAC line to line voltages for illumination. 277VAC line to neutral ought to be the upper limit. This would reduce the size of any arcs.
Now that LED is sweeping the market, there is reduced need for watts.
Additionally, ganging contactor neutrals under one wire nut ought to be discouraged. Such lighting control cabinets should have isolated neutral bars, instead. Why?
It then becomes possible to un-circuit a contactor during production hours without hazarding ungrounded electronic ballasts. A broken return is brutal on electronics. It's a nasty shock risk for the service electrician. A cheesy isolated neutral rail is a trivial expense to stop the problem.
(I've seen control cabinets with no less than 12 neutrals in #12 stuffed into big blue wire nut pairs. With a jumper linking them. The amps were no biggie. The complications while the system was up and running ( a 24hr shop ) made it a nightmare.