Section 113.50-5 - General requirements(a) Each vessel must have an amplifier-type announcing system that will supplement the general emergency alarm. This system must provide for the transmission of orders and information throughout the vessel by means of microphones and loudspeakers connected through an amplifier. If a decentralized-type system is used, its overall performance must not be affected by the failure of a single call station. This system may be combined with the general emergency alarm and fire detecting and alarm systems. The public address system must be protected against unauthorized use.(b) The announcing station must be located adjacent to the general emergency alarm contact maker or initiating device on the navigating bridge.(c) There must be a means to silence all other audio distribution systems at the announcing station.(d) The system may be arranged to allow broadcasting separately to, or to any combination of, various areas on the vessel. If the amplifier system is used for the general emergency alarm required by subpart 113.25 of this part, the operation of a general emergency alarm contact maker or initiating device must activate all speakers in the system, except that a separate crew alarm may be used as allowed by § 113.25-5(e)(2) .(e) The amplifier, and any device used to produce the general emergency alarm signal, must be provided in duplicate.(f) The power supply must be in accordance with the requirements of §§ 113.25-6 and 113.25-7 .(g) Each electrical subsystem in a weather location must be watertight or in a watertight enclosure and must meet Type 4 or 4X of NEMA 250 or IP 56 of IEC 60529:2013 (both incorporated by reference; see § 110.10-1 of this subchapter) requirements.CGD 94-108, 61 FR 28290, June 4, 1996, as amended at 62 FR 23910, May 1, 1997; USCG-2003-16630, 73 FR 65202, Oct. 31, 2008; USCG-2020-0075, 88 FR 25285, Apr. 26, 2023 88 FR 16369, 4/17/2023; USCG-2020-0075, 88 FR 25285, 4/26/2023