ceiling surface mount fluorescent light question
High output fluorescent lights do generate a fair amount of heat. If directly attached to a solid surface the ballast will over heat and may turn off to cool down.
The life of the light will be reduced due to the high heat. I always use 12 gauge single jack chain for mounting the 6 tube enclosed fixtures. I do have 5 or 6, 4 tube open fixtures that are directly mounted to the ceiling.
The enclosed fixtures when directly mounted shut down and some have to be power cycled to get them to restart (after finding this out all the enclosed fixtures were suspended and they worked great after that).