MOBILE HOMES AND MOBILE HOME PARKS 70-599

(b) Continuity and Operational Tests and Polarity Checks. Each mobile home shall be subjected to: (1) An electrical continuity test to ensure that all exposed electrically conductive parts are properly bonded; (2) An electrical operational test to demonstrate that all equipment, except water heaters and electric furnaces, is connected and in working order; and (3) Electrical polarity checks of permanently wired equipment and receptacle outlets to determine that connections have been properly made. 550-13. Calculations. The following method shall be employed in computing the supply-cord and distribution-panelboard load for each feeder assembly for each mobile home in lieu of the procedure shown in Article 220 and shall be based on a 3-wire, 120/240-volt supply with 120-volt loads balanced between the two legs of the 3-wire system. (a) Lighting and Small Appliance Load: Lighting Volt-Amperes: Length times width of mobile home floor (outside dimensions) times 3 volt-amperes per square foot; e.g., Length X width X 3 = lighting volt-amperes. Small Appliance Volt-Amperes: Number of circuits times 1,500 volt-amperes for each 20-ampere appliance receptacle circuit (see definition of "Appliance, Portable" with note) including 1,500 volt-amperes for laundry circuit; e.g., Number of circuits X 1,500 = small appliance volt-amperes. Total: Lighting volt-amperes plus small appliance = total volt-amperes. First 3,000 total volt-amperes at 100 percent plus remainder at 35 percent II volt-amperes to be divided by 240 volts to obtain current (amperes) per leg. (b) Total Load for Determining Power Supply. Total load for determining power supply is the summation of: (1) Lighting and small appliance load as calculated in Section 550-13(a). (2) Nameplate amperes for motors and heater loads (exhaust fans, air conditioners, electric, gas, or oil heating). Omit smaller of the heating and cooling loads, except include blower motor if used as air-conditioner evaporator motor. Where an air conditioner is not installed and a 40-ampere power-supply cord is provided, allow 15 amperes per leg for air conditioning. (3) 25 percent of current of largest motor in (2). (4) Total of nameplate amperes for: disposal, dishwasher, water heater, clothes dryer, wall-mounted oven, cooking units. Where number of these appliances exceeds three, use 75 percent of total. (5) Derive amperes for freestanding range (as distinguished from separate ovens and cooking units) by dividing the following values by 240 volts. 70-600 NATIONAL ELECTRICAL CODE Nameplate Rating Use 0 thru 10,000 watts 80 percent of rating Over 10,000 thru 12,500 watts 8,000 volt-amperes Over 12,500 thru 13,500 watts 8,400 volt-amperes Over 13,500 thru 14,500 watta 8,800 volt-amperes Over 14,500 thru 15,500 watts 9,200 volt-amperes Over 15,500 thru 16,500 watts 9,600 volt-amperes Over 16,500 thru 17,500 watts 10,000 volt-amperes (6) If outlets or circuits are provided for other than factory-installed appliances, include the anticipated load. See following Example for illustration of application of this calculation. Example A mobile home floor is 70 feet X 10 feet and has two small appliance circuits, a 1000-volt-ampere, 240-volt heater, a 200-volt-ampere, 120-volt exhaust fan, a 400-volt-ampere, 120-volt dishwasher, and a 7000-volt-ampere electric range. Lighting and small appliance load Lighting 70 X 10 X 3 VA/sq ft = 2100 volt-amperes Small appliance 1500 X 2= 3000 volt-amperes Laundry 1500 X 1= 1500 volt-amperes 6600 volt-amperes 1st 3000 volt-amperes at 100 percent 3000 volt-amperes Remainder (6600 - 3000) at 35 percent 1260 volt-amperes 4260 volt-amperes 4260 volt-amperes =17.75 amperes per leg 240 volts Amperes per leg A B Lighting and appliances 17.75