You use demand factors to adjust the rating of the main service for a building based on the expectation that at any given time, not all of the electrical equipment will be drawing at the full rated load. You can specify one or more demand factors for lighting, power, HVAC, or other systems in your project based on system load. In addition to the predefined demand factors, you can also create your own.
For example, for the load classification Kitchen, with a demand factor of 1.00, if you have 10 lights at 60 VA each, the load is 60 VA x 10 (lights) = 600 VA. Therefore, the lights for the load of this load category would be 600 VA. This value is accurate only if all the lights are turned on at the same time. To account for only half of the lights being turned on at a time, you would specify the demand factor as a constant value set to 0.5 (50%). The estimated load is then 600 VA X 0.5 (demand factor unit) = 300 VA.
Building codes determine what values to use for demand loads. For example, if the total receptacle on a panel is 20,000 VA, the demand load could be 15,000 VA depending on the local code.
Demand factors are assigned to load classifications, and load classifications are assigned to device connectors. The estimated load for a device is calculated by multiplying the load by the demand factor. See Load Calculations and Demand Load Calculation.
The estimated demand load is displayed in the panel’s instance properties (in the Properties Palette) and in the panel schedule. The panel schedule can also display the load for each load classification. See Panel Schedules.
You can specify a demand factor to calculate the estimated demand load on a circuit. The demand factor can be determined by:
You can specify a constant demand factor to be applied to the load.
You can specify several quantity ranges for connected objects and apply a different demand factor to each range or apply the same demand factor to all objects depending on how many objects are connected.
In the example in the table below, you can specify a demand factor based on a percentage of the entire quantity and specify that the demand factors are calculated incrementally for each range.
| Greater Than | Less Than or Equal To | Demand Factor |
|---|---|---|
| 0 | 1 | 125% |
| 2 | 3 | 100% |
| 4 | unlimited | 60% |
These settings will apply a 125% demand factor to the object with the largest load, a 100% demand factor to the objects with the second and third largest loads, and a 60% demand factor for any additional objects after the third object.
You can specify several load ranges for an object and apply a different demand factor to each range or apply the same demand factor to the total load connected to the panel.
In the example in the table below, you can specify a demand factor based on a percentage of the entire load and specify that the demand factors are calculated incrementally for each range.
| Greater Than | Less Than or Equal To | Demand Factor |
|---|---|---|
| 0 | 3000VA | 100% |
| 3000VA | 10,000VA | 50% |
| 10,000VA | unlimited | 30% |
These settings will apply a 100% demand factor to loads less than 3000VA, a 50% demand factor to loads between 3000VA and 10,000VA, and a 30% demand factor for loads greater than 10,000VA.