GREI guide
Sockets and lighting circuits: the GREI rules
How many sockets on a circuit, how many lighting circuits, which appliances on a separate circuit: here is what the GREI says for a domestic installation.
At most 8 sockets per circuit
In domestic installations, the number of single or multiple socket outlets is limited to eight per final circuit (subsection 5.3.5.2). A double or triple socket therefore counts as one.
A fixed appliance, or a group of fixed appliances controlled by the same switch, counts as one socket.
All sockets have an earth contact connected to the protective conductor, except at safety extra-low voltage or behind an individual isolating transformer.
At least two lighting circuits
As soon as the dwelling has more than two rooms or areas, the lighting is split over at least two separate circuits.
Sockets and lighting on the same circuit
Sockets, lighting and fixed appliances may share a circuit, except appliances that need a dedicated circuit. That circuit then follows the rules for socket circuits.
Appliances on a separate circuit
Every fixed appliance of 2600 W or more has its own dedicated circuit, such as the washing machine, dishwasher, tumble dryer, and the electric cooker, hob and oven (subsection 5.2.1.2).
Cross-section, circuit breaker and RCD
A 2.5 mm² socket circuit is protected by a circuit breaker of 20 A at most, and a 1.5 mm² lighting circuit by a circuit breaker of 16 A at most (table 4.11).
Socket and lighting circuits are under an RCD of 30 mA at most, and each 30 mA RCD protects 8 circuits at most.
With Vonkcad
Place the points, the circuits follow
- A circuit is created with the first socket placed on the plan
- 8 sockets per circuit and dedicated circuits checked as you draw
- “Equip the room” suggests the sockets and circuits for the kitchen or laundry
- Circuit letters and point numbers assigned on their own
Read also
The single-line diagram
What it must contain, how circuits and points are marked, the symbols.
The layout plan
The items to show, the letter-and-number marking, keeping it up to date.
The acceptance inspection
The documents to prepare, what the approved body checks, the report.
Cable size and circuit breaker
Table 4.11: the maximum rating for each cross-section, and dedicated circuits.
RCDs
300 mA at the origin, 30 mA for sockets, lighting and the bathroom, earth electrode.
The bathroom
Zones 0, 1 and 2, permitted equipment, the RCD and equipotential bonding.
Voltage drop
What the GREI says, the 3 % and 5 % values, and the calculation with an example.
This guide summarises the GREI Book 1, 2026 version. Only the official text published by the FPS Economy is authoritative.
Your next file, with Vonkcad
Single-line diagram, layout plans, GREI check and PDF file: everything is linked in one project. Free during the beta.
