(a) Fire detecting devices shall be located throughout the building in accordance with the generally accepted standards listed in the appendix to these rules and regulations.^*

(b) Thermostats shall be located so as to operate promptly and shall be protected from injury. Not more than 65 thermostats will be permitted on any single circuit.

(c) Continuous line fire detecting wire shall be located so as to operate promptly and shall be protected from injury. In no case shall any point on the ceiling be more than seven and one-half feet from the nearest portion of the fire detecting wire. A single circuit of fire detecting wire shall not exceed 1,000 feet in length, nor shall any circuit be used to protect more than the area of one floor or story except with the approval of the department.

(d) Continuous line fire detecting pneumatic tubing shall be located so as to operate promptly and shall be protected from injury. In no case shall any part of the ceiling be more than 15 feet from the nearest portion of the tubing; nor shall any enclosed space or separate room contain less than 25 feet of exposed tubing or less than five per cent of the length of the circuit. A single circuit of fire detecting tubing shall not exceed 1,000 feet in length, nor shall such pneumatic tubing be enclosed in conduit or other covering except when necessary to isolate signals or to protect the tubing from mechanical injury.