IMHO, this matter should be discussed with the AHJ in your particular area.
Under some circumstances, a 'locked' cover/door may be acceptable, providing that the lock is a 'break-away' type to allow access to the disco in an emergency. Equipment in 'public places' can/may be subject to vandalism, and access to a disco may create more of a safety hazard. We had a rash of main discos being 'turned off' in a mall by kids, as the discos are outside.
Talk to your local AHJ.