shall be lockable in the close position the breaker feeding the Fire Alarm Panel?
Are you asking if it is permissible or required?
For example:
II. Non?Power-Limited Fire Alarm (NPLFA) Circuits
760.41 NPLFA Circuit Power Source Requirements.
(A) Power Source. The power source of non?power-limited
fire alarm circuits shall comply with Chapters 1 through 4, and
the output voltage shall be not more than 600 volts, nominal.
The fire alarm circuit disconnect shall be permitted to be secured
in the ?on? position.