I have recently taken a contract with a reputable electrical systems installing company. The electricians are responsible for installing all needed raceways and pathways for the installation of the fire alarm. This is a high rise building. The electricians are telling me that a mechanical room intended for the sole purpose of both isolating and protecting the electrical systems (which includes the fire alarm) from normal building use and occupant tampering meets, and has met on all of their installations in the past, the intent of approved solid guard protection mentioned in NEC 70 article 760.130 B (1) & (2). Any thoughts from anyone before I ask for approval from local AHJ?
Thanks in advance.
Simply isolating the cables from casual tampering does not necessarily meet the requirements.
I'm going to assume that this mechanical room is duplicated on each floor and the cable(s) pass from floor to floor into each such dedicated mechanical room. From this mechanical room on each floor the cable(s) go out the the alarm or notification devices on that floor.
As the cable passes through the floor, it has to be protected per 760.130 B(2), typically by running it in EMT or PVC. The "adequate protection" part might be met by running it in the wall, or if there is a "chase" recessed into the wall to accept the cable and allowing it to be fastened every 18".
Of greater importance to your wiring methods is the fire alarm system design. If this high-rise employs "floor above, floor below, floor of incidence" alarming, then you need to provide 2 hour fire protection for all your riser cable, typically using circuit integrity (CI) listed cable. Very expensive, not easy to work with. The same applies if you have "areas of refuge" where limited mobility individuals might have to wait for resuce by the fire department. In that case, the two-way communication cables must also be similarly protected/listed.
