Panels grow
Every real household adds circuits over time: an air conditioner, a garden line, an EV charger, a workshop. If the enclosure is packed on day one, any addition means replacing the enclosure — the most expensive change possible.
The 20–30% rule
Standards and common sense agree: leave at least 20–30% of DIN-rail space free. On a 24-module panel that is 5–7 free modules — enough for a new RCBO group or a small sub-feed.
What PlanMyPanel does
The generator adds your chosen reserve on top of the calculated module count and then picks the next standard enclosure size (12/18/24/36/54 modules). The rule engine warns you when an edited panel drops below the reserve.