Which the basic requirements to get a job in Low current's company and spicalized in Fire alarm system/CCTV/Access control?

Well at first you cant be responsible for all departments at the same time LC companies will have people divided/ specialized in each domain, Access control and Fire alarm are simple logic where as CCTV is a different matter the size of the recording and pixels of the camera's are client related matter.

You need to know programming languages like C++ and java, and in the case of fire alarm getting an NFPA certification is huge plus