FLOATING BUILDINGS

70-627 (FPN): For clearances of conductors over 600 volts, nominal, see National Electrical Safety Code, ANSI C2-1990. 551-80. Underground Service, Feeder, Branch-Circuit and Recreational Vehicle Site Feeder Circuit Conductors. (a) General. All direct-burial conductors, including the equipment grounding conductor if of aluminum, shall be insulated and identified for the use. All conductors shall be continuous from equipment to equipment. All splices and taps shall be made in approved junction boxes or by use of material listed and identified for the purpose. (b) Protection Against Physical Damage. Direct-buried conductors and cables entering or leaving a trench shall be protected by rigid metal conduit, intermediate metal conduit, electrical metallic tubing with supplementary corrosion protection, rigid nonmetallic conduit, or other approved raceways or enclosures. Where subject to physical damage, the conductors or cables shall be protected by rigid metal conduit, intermediate conduit, or Schedule 80 rigid nonmetallic conduit. All such protection shall extend at least 18 inches (457 mm) into the trench from finished grade. (FPN): See Section 300-5 and Article 339 for conductors or Type UF cable used underground or in direct burial in earth. 551-81. Receptacles. A receptacle to supply electric power to a recreational vehicle shall be one of the configurations shown in Figure 551-46(c) in the following ratings: (a) 50-Ampere. 125/250 volts, 50-ampere, 3-pole, 4-wire, grounding type for 120/240-volt systems. (b) 30-Ampere. 125-volt, 30-ampere, 2-pole, 3-wire, grounding type for 120-volt systems. (c) 20-Ampere. 125-volt, 20-ampere, 2-pole, 3-wire, grounding type for 120-volt systems. (FPN): Complete details of these configurations can be found in American National Standard Dimensions of Caps, Plugs and Receptacles, ANSI C73.17-1972; ANSI C73.13-1972; and C73.12-1972.