Lighting Design – Planning Light Circuits
Well-planned lighting design is an essential part of every electrical installation. The right number and distribution of lighting circuits, suitable switching types and correct LED driver sizing ensure comfort, energy efficiency and safety.
Planning Tip
Plan the lighting early together with the room concept. Subsequent changes to light switch positions or additional ceiling outlets are complex and expensive.
Planning Lighting Circuits
Lighting circuits should be carefully planned to ensure even load distribution and flexible control.
Basic Rules for Lighting Circuits
- Provide at least one separate lighting circuit per room
- Equip large rooms (> 20 m²) with multiple circuits for different lighting scenes
- Protect lighting circuits with max. 10 A (B10 breaker) and 1.5 mm² cable
- Always run outdoor lighting on a separate circuit with its own RCD
Recommended Illuminance Levels (Lux)
EN 12464-1 specifies minimum illuminance levels for different areas. For residential spaces, these serve as guidelines for comfortable lighting.
| Room | Rec. Lux | Notes |
|---|---|---|
| Living Room | 300 lx | Dimmable general lighting + accent lighting recommended |
| Kitchen | 500 lx | Under-cabinet task lighting for work surfaces essential |
| Bathroom | 300 lx | Mirror lighting separate, observe protection zones |
| Bedroom | 200 lx | Bedside reading lamps separately switchable |
| Home Office | 500 lx | Glare-free task lighting per EN 12464-1 |
| Hallway / Staircase | 100 lx | Motion sensors or push-button switching recommended |
Switching Types for Lighting
Depending on room size and access points, different switching types are used. The choice of switching type affects wiring complexity and user comfort.
Simple Switch
The simplest circuit: one switch controls one light. Suitable for small rooms with only one entrance such as storage rooms, guest WC or basement rooms.
Two-Way Switch
Two switches control one light – ideal for rooms with two access points such as bedrooms (door + bedside), hallways or connecting rooms.
Intermediate (Crossover) Switch
Three or more switches control one light. Used in long hallways, large living rooms or staircases with multiple floors.
Push-Button / Dimmer Circuit
Via push buttons and a central dimmer actuator, brightness can be continuously adjusted. Ideal for living and bedrooms. Standard in KNX/smart home systems.
LED Drivers and Transformers
Modern lighting is almost exclusively LED-based. Correct selection of the LED driver is crucial for longevity and dimmability.
LED Driver Selection Tips
- Size driver power at least 20% above the total load of connected LEDs
- For dimmable installations: choose DALI, 1-10V or trailing-edge compatible drivers
- Observe minimum load: many dimmers require a minimum load of 10-25W – may not be reached with few LEDs
- LED transformers for low-voltage systems (12V/24V) must be electronic – do not use conventional halogen transformers
Room-by-Room Lighting Planning
Each room has specific lighting requirements. Here are the key planning considerations for the most common room types.
Living Room
Combine general lighting (ceiling), accent lighting (spots, indirect lighting) and task lighting (reading light). Plan at least 2-3 separate lighting circuits with dimming capability.
Kitchen
Under-cabinet task lighting is essential (500 lux). Additionally, general ceiling lighting and possibly mood lighting above the dining table. Separate circuits for task and ambient light.
Bathroom
Strictly observe protection zones! Mirror lighting separate with min. 300 lux. General lighting must be wet-room rated (IP44/IP65). Night light option with dimmed warm white recommended.
Outdoor Lighting
Separate circuit with dedicated RCD (30 mA). IP44 or higher for all outdoor luminaires. Motion sensors for entrances and pathways. Plan garden lighting with 12V/24V SELV system.