How do you calculate residential electrical load?
How do you calculate residential electrical load?
Calculating Load
- Add together the wattage capacity of all general lighting branch circuits.
- Add in the wattage rating of all plug-in outlet circuits.
- Add in the wattage rating of all permanent appliances (ranges, dryers, water heaters, etc.)
- Subtract 10,000.
- Multiply this number by .
- Add 10,000.
What is the unit load per square foot for dwelling units?
3 volt-amperes per square foot
Table 220.12 stipulates a minimum unit load of 3 volt-amperes per square foot for dwelling units.
How do you calculate electrical load per square foot?
Divide the wattage consumed in the room by its area in square feet to calculate watts per square foot. In our example, 650 watts divided by 192.89 square feet is 3.37 watts per square feet.
How many steps are there in this class to figure out a load calculation for a dwelling unit?
The standard method consists of three calculation steps: General lighting VA load. When calculating branch circuits and feeder/service loads for dwellings, include a minimum 3VA per sq ft for general lighting and general-use receptacles [220.12].
What is the general lighting load of a dwelling unit?
Table 220.12 General Lighting Loads by Occupancy
| Unit Load | ||
|---|---|---|
| Type of Occupancy | Volt-amperes/m2 | Volt-amperes/ft2 |
| In any of the preceding occupancies except one-family dwellings and individual dwelling units of two-family and multifamily dwellings: | ||
| Assembly halls and auditoriums | 11 | 1 |
| Halls, corridors, closets, stairways | 6 | 1/2 |
What is the minimum size service for a dwelling unit?
Explanation of Solution For a one family dwelling, according to National Electric Code NEC 230.79(C), the required minimum-size service is 100 amperes.
How many watts do you need per square foot?
The number of watts = area x 10. This result is valid for houses containing rooms whose ceilings are 8 feet high. In the case of modern homes having higher ceilings than 8 feet, the rule of thumb for the calculation is 1.25 watts per cubic foot.
How do you calculate electrical service size?
Minimum service size can be found by adding up the total wattage that will be used, counting the first 10 kW at 100%, and using a 40% demand factor on all the rest. Once the calculated demand is determined in terms of wattage, divide that by 240 volts to convert it into amps. This would be your required service size.
How do you calculate breaker size wires and watts?
To calculate the breaker size, simply divide the adjusted wattage by 240 volts to find the rated amperage needed for your subpanel. Often, the result is not a common circuit breaker size.