Section 143.555 - Electrical power sources, generators, and motors(a)General requirements.(1) There must be a source of electrical power sufficient for:(i) All essential systems as defined by § 136.110 of this subchapter;(ii) Minimum conditions of habitability; and(iii) Other installed or portable systems and equipment.(2) Generators and motors must be suitably rated for the environment where they operate, marked with their respective ratings, and suitably protected against overcurrent.(3) A towing vessel, other than an excepted vessel, must have a backup or a second power source that has adequate capacity to supply power to essential alarms, lighting, radios, navigation equipment, and any other essential system identified by the cognizant OCMI or a TPO.(b)Specific requirements.(1) The owner or managing operator must complete a load analysis that shows that the electrical power source is sufficient to power the sum of connected loads described in paragraph (a)(1) of this section utilizing an appropriate load factor for each load. A record of the analysis must be retained by the owner or managing operator.(2) Installed generators and motors must have a data plate listing rated kilowatts and power factor (or current), voltage, and rated ambient temperature.(3) Generators must be provided with overcurrent protection no greater than 115 percent of their rated current and utilize a switchboard or distribution panel.(4) Motors must be provided with overcurrent protection that meets Parts I through VII, Article 430 of NFPA's National Electrical Code (NEC) (incorporated by reference, see § 136.112 of this subchapter). Steering motor circuits must be protected as per Part 4 Chapter 6 Section 2, Regulation 11 (except 11.7) ofABS Rules for Building and Classing Steel Vessels Under 90 Meters (295 feet) in Length (incorporated by reference, see § 136.112 of this subchapter).(5) Generators and motors installed in machinery spaces must be certified to operate in an ambient temperature of 50 °C or be derated, or it can be shown that 40 °C ambient temperature will not be exceeded in these spaces.(6) Each generator and motor, except a submersible-pump motor, must be in an accessible space which is adequately ventilated and as dry as practicable, and must be mounted above the bilges.(7) A generator driven by a main propulsion unit (such as a shaft generator) may be considered one of the power sources required by paragraph (a) of this section.(8) Other than excepted vessels, each towing vessel must be arranged so that the following essential loads can be energized from two independent sources of electricity:(i) High bilge level alarm required by § 143.230 ;(ii) Emergency egress lighting, unless the requirements of § 143.410(b)(1) or (2) are met;(iv) Pilothouse lighting;(v) Engine room lighting;(vi) Any installed radios and navigation equipment as required by §§ 140.715 and 140.725 ;(vii) All distress alerting communications equipment listed in §§ 140.715 and 140.725 ;(viii) Any installed fire detection system; and(ix) Any essential system identified by the cognizant OCMI or TPO, if applicable.(9) If a battery is used as the second source of electricity required by paragraph (b)(8) of this section, it must be capable of supplying the loads for at least three hours. There must be a means to monitor the condition of the battery backup power source.