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Voltage: Enter the source nominal voltage. Use the larger voltage of the system. Example: For a 120/240V Use 240V Square Footage: Measure the total square footage of the occupancy using the outside dimensions. Do not include open porches, unused or unfinished spaces not adaptable for future use. Small Appliance Branch Circuits: Enter the number of small appliance branch circuits. At least 2 are required for dwelling units.210-11(c)(1)Appliance Branch Circuit - A branch circuit that supplies energy to one or more outlets to which appliances are to be connected, and that has no permanently connected lighting fixtures that are not part of an appliance. Laundry Branch Circuits: Enter the number of laundry branch circuits. At least 1 is required for dwelling units. 210-11(c)(2) Fastened In Place Appliances: Use Volt Amps or Watts. These are appliances you can not pick up and carry out of the house without using some kind of tool. Examples of fastened in place appliances: electric water heater, attic fan, disposal, trash compactor and dish washer. Do not include electric ranges, air conditioners, clothes dryers or space heaters. Use the nameplate ratings. Horse power ratings should be converted to Amps using T430.148, then converted to VA by multiplying by the rated voltage (i.e. 120 volts) Clothes Dryers:(optional) Enter the rating in volt-amps. A clothes dryer is not required. If there will be no clothes dryers then enter a zero. The minimum rating is 5000va so, use 5000va or the name plate rating which ever is larger. If your rating is listed in kW then multiply that rating by 1000. for example 6kW = 6000va. The neutral load will be calculated at 70% of the dryer load. Household Cooking Appliances:(optional) Enter in kilo-watts the household cooking appliances rated over 1.75kW. Examples of Household cooking appliances are Ranges, Ovens, Cooktops rated over 1.75kW. If there will be no household cooking appliances over 1.75kw then skip this section. The neutral load will be calculated at 70% of the total calculated load. Heating or Air Conditioning: Enter in volt-amps the larger of either the ac or heating loads. For example you have central system comprising of an AC compressor(4000va), condenser fan(240va), air handler(345va) and heat coils(15000va). You also have a space heater(3500va). Now what is the largest load that will be running at any time? Will it be when you run the heating or the AC? You can eliminate one since you will not be using both at the same time. When the AC is being used the compressor, condenser, and air handler will be running. This gives us a total AC load of 4585va. The total heating load is the sum of the heat coils, air handler and the space heater which in this case is 18845va. I would enter 18845 and select the Heater button. If your compressor also serves as a heat pump it should be added to the heating load. Heating or Air Conditioning Neutral: Enter the neutral load in Volt Amps. This is the same as the 120V load. Example: An AC system usually consists of a condenser fan motor(208-240V), compressor motor(208-240V) and a blower motor(120V). In this case I only need the Volt-Amps of the blower motor. Use the nameplate ratings. Horse power ratings should be converted to Amps using T430.148, then converted to VA by multiplying by the rated voltage (ie 120 volts). A 1/2 horse motor is a large common blower motor. The same is true with heating find all the 120V loads in the system and add them up. For this calculation Watts are the same as Volt-Amps. Largest Motor: Enter in volt-amps the larges motor. In most cases this will be the AC compressor. If this motor is only listed in horse power it should be converted to Amps using T430.148, then converted to VA by multiplying by the rated voltage (ie 120 volts). If this is a 120V motor check the neutral box. |