46 CFR § 181.120 - Equipment installed but not required.
(a) Fire extinguishing equipment installed on a vessel in excess of the requirements of §§ 181.400 and 181.500 must be designed, constructed, installed, and maintained in accordance with a recognized industry standard acceptable to the Commandant (CG-ENG-4).
(b) Use of non-approved fire detection systems may be acceptable as excess equipment provided that -
(1) Components are listed by an independent, nationally recognized testing laboratory as set forth in 29 CFR 1910.7, and are designed, installed, tested, and maintained in accordance with an appropriate industry standard and the manufacturer's specific guidance;
(3) Coast Guard plan review is completed for wiring plans.