Calculate dwelling electrical load and required service size with demand factors.
Demand factors apply because connected load far exceeds simultaneous load. Heating and cooling are not added together since only the larger can run, but electric vehicle charging is treated as a continuous load at full value. Adding an electric vehicle charger is what most often pushes an existing 100 amp service over its limit, and this calculation is how that is established before the work starts.
Electrical Load
First 3,000 VA at 100 per cent, remainder of general load at 35 per cent, plus appliances and HVAC
First 3,000 VA at 100 per cent, remainder of general load at 35 per cent, plus appliances and HVAC Demand factors apply because connected load far exceeds simultaneous load. Heating and cooling are not added together since only the larger can run, but electric vehicle charging is treated as a continuous load at full value.
Adding an electric vehicle charger is what most often pushes an existing 100 amp service over its limit, and this calculation is how that is established before the work starts.
This calculator takes 5 inputs: Floor area, Fixed appliance load, Largest of heating or cooling load, Electric vehicle charger, Supply voltage. The pre-filled defaults are a realistic starting point — replace them with figures from your own environment for a result you can act on.