What type of installation is NOT allowed for ballast servicing in fluorescent luminaires?

In the context of fluorescent luminaires, the prohibition of a disconnecting means for servicing aligns with safety concerns outlined in the National Electrical Code. The reason having a luminaire without a disconnecting means is not permitted is due to the potential hazards it poses to workers.

When servicing ballasts within fluorescent luminaires, technicians need a safe way to ensure that the electrical supply is cut off to prevent accidental electrocution or electrical shock during maintenance work. A disconnecting means allows for this safety protocol to be effectively implemented.

Conversely, other options provide either external or internal ways to ensure that ballasts can be accessed and serviced safely. An external disconnecting means provides a clear cut-off outside of the luminaire, while internal servicing might involve procedures deemed compliant with safety standards that still allow for some level of protection during maintenance tasks. Having serviced ballasts connected could refer to being able to work on them while still connected to power, which typically should be avoided unless proper safety measures are in place.

Thus, the lack of a disconnecting means in certain luminaire installations fails to establish a necessary safety practice, emphasizing the importance of compliance with the NEC guidelines for electrical installations and maintenance.