Adding up a home
The incomer must carry the realistic peak load of the home. We sum the loads of all circuit groups: lighting and socket estimates per room plus the nameplate power of every dedicated appliance.
Demand factor
Not everything runs at once — the oven, the dishwasher and the boiler rarely peak together. Standards apply a demand factor to the raw sum to get a realistic maximum.
The exception is continuous loads: an EV charger or underfloor heating runs for hours at full power, so PlanMyPanel counts them in full (factor 1.0) and applies the demand factor only to the rest.
Checking the main breaker
The estimated load current is compared with the main breaker rating. If the load exceeds what the incomer can carry, the app warns you: the fix is a bigger supply contract or staggering heavy loads. Undersized incomers trip on winter evenings; oversized ones are not allowed by the utility.