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Lighting Regulations UK: the 75 Lumens Per Circuit-Watt Rule, Switching, Outdoor Lights and Part P

Lighting regulations in UK homes are lighter than most people expect, but they do apply whenever you fit new light fittings, in a new build or an existing house. In England the energy rules sit in Approved Document L: each new internal light fitting needs lamps with an efficacy of at least 75 lumens per circuit-watt, lights need switching by room or zone, and outdoor lights need automatic controls. The electrical side falls under Part P. Here is what each rule means when you are planning a renovation.

Where the lighting rules come from

Fixed lighting counts as a "fixed building service" under the Building Regulations 2010, so it has to meet the energy efficiency requirement in Part L. The practical guidance is in Approved Document L, Volume 1: Dwellings (2021 edition, with 2023 amendments), paragraphs 6.57 to 6.60. It covers fixed lighting only: lamps you plug in, such as floor and table lamps, are outside the rules, and so are emergency escape lighting and specialist lighting like display or stage lights.

A new edition of Approved Document L, published in 2026, applies in England to most building work from 24 March 2027. If your project starts close to that date, ask your building control body which edition it will check against.

The 75 lumens per circuit-watt rule

Paragraph 6.58 says that where installed in a new or existing dwelling, each internal light fitting should have lamps with a minimum luminous efficacy of 75 light source lumens per circuit-watt.

• Light source lumens means the light output of all the lamps in the fitting, measured as the average initial (100-hour) output.
• Circuit-watt means the power drawn by the lamps plus any control gear, such as transformers and LED drivers.

In practice that rules out old incandescent and halogen lamps, which come in well below 75, and most compact fluorescents. Most mainstream LED lamps and integrated LED fittings clear it comfortably, but check the specification, especially for decorative filament-style LEDs, dim-to-warm lamps and fittings with a separate driver, where the driver losses count against you. A fitting that gives 800 lumens and draws 8 watts including its driver manages 100 lumens per circuit-watt; one that gives 400 lumens from 7 watts manages only 57.

Paragraph 6.57 adds a common-sense duty: fixed lighting should give levels appropriate to how the space is used, and rooms should not be over-lit. The guidance also accepts that householders will often choose the lamps themselves, so the rule bites hardest on integrated LED fittings, where you cannot change the lamp later.

Switching: control by room or zone

Paragraph 6.59 says internal light fittings should have local controls so that the lighting in each space or zone can be controlled separately. The controls can be manual switches, automatic sensors or a mix. For an open-plan kitchen and living area, that means the kitchen run, the dining table and the sitting area should each be switchable on their own, which is good design anyway. Our guide to lighting design basics covers how to layer task, ambient and accent lighting.

Outdoor lighting rules

Fixed external lighting, meaning lights fixed to the outside of the house and wired to your own supply, has two requirements under paragraph 6.60:

1. Automatic daylight control, so the lights switch off when it is light, for example a dusk-to-dawn photocell.
2. Presence detection, so the lights switch off once the area is empty, unless the lamps exceed 75 lumens per circuit-watt, in which case manual switching is acceptable.

Lighting in the shared areas of a block of flats is not counted as fixed external lighting for this purpose. Garden lights on a separate circuit can still bring Part P into play, so plan the wiring before the landscaping.

Part P: when lighting work must be notified

Electrical safety is covered by Part P. Most lighting jobs are not notifiable, but these are:

• fitting a new circuit, for example a dedicated lighting circuit for an extension or a garden;
• replacing a consumer unit;
• adding to or altering a circuit in a special location, which mainly means the zones around a bath or shower.

Swapping a light fitting, adding a light point to an existing circuit in a living room or bedroom, or changing a switch are not notifiable, though they must still be done safely to BS 7671. The easiest route for notifiable work is a registered competent person electrician, who self-certifies and gives you a certificate. Our Part P guide has the detail.

Bathrooms, downlights and fire safety

In a bathroom, the IP rating a fitting needs depends on which zone it sits in. Zone 1, directly above a bath or shower, generally needs at least IPX4, and many installers specify IP65. Our guide to bathroom zones sets out each zone's limits.

Recessed downlights cut holes in the ceiling, and where that ceiling is a fire separation, such as between floors in a loft conversion or below a flat above, they can weaken it. Fire-rated downlights, or covers tested with the fitting, restore the protection. See our guide to fire-rated downlights before you plan a grid of spotlights.

Do I need building regulations approval to change my lights?

For a straight swap of a fitting or lamp, no application is needed, but the new fitting's lamps should still meet the 75 lumens per circuit-watt standard. For a renovation, an extension or a loft conversion, lighting is checked along with the rest of the work, so specify compliant fittings and switching in the drawings. Your building control body or competent person will want to see that external lights have the right controls and that any notifiable electrical work has been certified.

The rules above are for England. Wales, Scotland and Northern Ireland have their own building regulations and guidance documents, so check the local version if your project is outside England.

More guides on design and the regulations on the Vertigo Interiors homepage.