The consumer unit is the brain of the installation: every circuit has its breaker, every row its residual-current protection. Here is its composition rule by rule, per the French NF C 15-100 standard (2024 edition, applicable since September 2025).
The architecture (diagram)
The composition rules
- 30 mA RCDs: at least 2 per dwelling, rated 40 A or 63 A to suit the load. Type A for hobs, washing machines and EV chargers; type AC (or F) for the rest.
- One breaker per circuit, rated to the cable size: see our cable size table.
- 20 % spare slots minimum — the future air-conditioner or EV charger will thank you.
- Technical space: 600 × 250 mm of floor reserved floor-to-ceiling; controls between 0.90 and 1.80 m.
- Labelling: every outgoing circuit labelled (room + use) — required, and vital at the first fault.
- Surge arrester: mandatory in storm-prone areas or with a lightning rod; recommended everywhere.
In renovation
Replacing an old fuse board with a modern RCD board is THE best safety investment (1 to 2 days of work). With the walls open, run the conduits properly and plan enough sockets.