30 CFR § 75.1103-7 - Electrical components; permissibility requirements.
The electrical components of each automatic fire sensor and warning device system shall:
(a) Remain functional when the power circuits are deenergized as required by § 75.706; and
(b) Be provided with protection against ignition of methane or coal dust when the electrical power is deenergized as required by § 75.313, but these components shall be permissible or intrinsically safe if installed in a return airway.
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