Lighting built into joinery: drivers, heat and access

At a glance

Typical behaviour from general practice: confirm against the strip, profile and driver data sheets. Only the heat principle and the replaceability rule are sourced.

Choose the light source, and draw the section

Three questions settle most of a lit-joinery design. What will the light fall on, and will the source be seen? Where does the heat go? And how will each part be replaced when it fails? Our live libraries and wardrobes pages say integrated LED lighting is standard; this sheet sets out what a specification should fix so that it works and can be repaired. It gives principles, not a design: the lighting designer and a competent electrician settle the details.

The table compares the usual options. It is general practice, not a ranking from a source, so confirm each against the supplier's data sheets. Draw the section at the same time as the carcase: the channel, rebate or groove has to be routed before assembly, with room for the profile, the diffuser and the cable.

• Shelf-front rebate. The profile sits in the front edge, lighting the shelf below. Allow for the profile width and depth (w and d in the drawing) from its data sheet.
• Cove. A strip behind an upstand on top of a cabinet lights the ceiling or wall. Keep the upstand tall enough to hide the source from standing eye height, and the cove reachable for cleaning and replacement.
• Under-shelf. A strip behind a small front lip washes the shelf below. The lip hides the source; it must not trap the heat.
• Wardrobe jamb. A vertical strip in a groove at the door jamb lights hanging space evenly from the side. A door switch or sensor changes the controls, not the section.
• Handle-free reveal. A strip in the lower edge of an upper panel lights the finger-pull gap. Keep the gap clean and the profile removable from below.

Drivers and wiring: where the mains stops

A 12 V or 24 V strip is extra-low voltage, which Approved Document P defines as not exceeding 50 V a.c. or 120 V ripple-free d.c., whether between conductors or to earth. The driver converts the mains supply to it. So the driver, and the cable that feeds it, are on the mains side and are fixed wiring for a competent electrician; only the low-voltage side is the joiner's to route.

The wiring standard is BS 7671. In dwellings in England, Approved Document P (2013 edition) says electrical installations should be designed and installed to it (paragraph 1.1) and that installing prefabricated modular wiring linked by plug and socket connectors, for example for kitchen lighting systems, is within Part P, but is notifiable only if it involves a new circuit, a consumer unit replacement or alterations to circuits in a special location (paragraphs 2.5 and 2.9). Non-notifiable work should still be designed, installed, inspected, tested and certified to BS 7671 (paragraph 3.13). Part P applies to dwellings; in hotels, restaurants and offices it does not, but BS 7671 remains the standard. In the 2008 edition of BS 7671, extra-low-voltage lighting installations had their own regulations (group 559.11), covering protection against shock (SELV) and against fire from a short circuit. The research file for this sheet places them in Section 715 of the current edition. We did not read the current edition, so confirm the numbering and the rules.

Place the driver for access and air.

• Reachable. In a compartment behind a removable hatch, a plinth panel or a top void, fixed with screws or magnets, not glue. Size the hatch from the driver's dimensions on its data sheet plus clearance for hands and tools: [ ] mm by [ ] mm. We give no universal figure.
• Ventilated. A driver makes heat too. Follow its data sheet for the maximum ambient temperature, leave air paths top and bottom, and do not bury it in a sealed box.
• Not overloaded. Load it to no more than [80] per cent of its rated output, or whatever the supplier states, and add up the strip power, not the length.
• Isolatable. A switched spur or isolator on the mains feed lets the electrician make the driver safe before the hatch is opened.
• Close to the load. Keep the low-voltage runs short. The table shows why with example figures only: the current is the power divided by the voltage, so a 24 V strip carries half the current of a 12 V strip of the same power, and a run that carries less current loses less voltage in its copper tracks. The strip's data sheet gives its maximum run length: ask for it in writing.
• Dimming. The driver and the dimmer or controller must suit each other; see dimming protocols.
• Sequenced. The electrician runs the mains to the driver position and any chases before the joinery is fixed (first fix), then connects and tests after the strip and driver are in (second fix). Agree who does each, and when.

Example figures only: 14.4 W per metre is an assumption, not a product. Current is power divided by voltage.

Heat: what the sources say and what to ask

LEDs are not cool. A US Department of Energy fact sheet (PNNL, February 2007) says LEDs make little or no infrared but turn only a fraction of their power into light (15 to 25 per cent for the best devices of that time), and the rest is heat that must be conducted from the LED to the board and on to a heat sink or the luminaire body. Too much heat shifts colour and cuts output in the short term, and speeds the loss of light over time. In one example in the sheet, 11 degrees Celsius more at the LED cut the estimated life to 70 per cent output from about 37,000 hours to about 16,000. Three things set that temperature: the drive current, the thermal path and the ambient temperature. The figures are dated and for one 2007 device, and efficacy has improved since, so we take the principle, not the numbers.

For joinery the principle is practical. Give the strip a thermal path, which is why a strip in an aluminium profile is the default, and do not let the cabinet trap the heat: leave air around drivers and do not wrap a strip in insulating material. Timber does not carry heat away well (general knowledge, not read in a source), so a strip bonded straight to timber has little path.

Heat on timber. An IET article on Section 559 of BS 7671:2008 says that BS EN 60598-1 defines a non-combustible surface as one incapable of supporting combustion, that wood and wood-based material over 2 mm thick counts as flammable, and that a luminaire marked with the symbol for direct mounting on normally flammable surfaces is limited so that the mounting surface does not exceed 90 degrees Celsius, even if a component fails. Luminaires that cannot meet that carry a warning notice or a different symbol. The article adds that the marking requirements were then changing and tells readers to check the latest edition, and web pages we saw disagree about the status of the older mark, so do not rely on a symbol you remember. Regulation 559.5.1 of that edition also asks the installer to account for the thermal effect on the surroundings, including the maximum power the lamps dissipate, the fire resistance of adjacent material and the minimum distance to combustible material.

So ask the supplier, in writing, for:

• the mounting-surface statement in the luminaire or strip instructions: is it suitable for fixing to timber or wood-based board, and for an enclosed space;
• the maximum ambient or case temperature, and the maximum strip power per metre for the profile you have chosen;
• the driver's ambient limit and its ventilation clearances;
• whether a compartment in the joinery counts as the enclosure the data sheet assumes.

Replace without dismantling

The rule we read. The Ecodesign for Energy-Related Products and Energy Information (Lighting Products) Regulations 2021 (SI 2021/1095) define a 'containing product' as a product containing light sources or separate control gear, and say it includes household appliances containing light sources and 'furniture containing light sources (for example display cabinets)' (regulation 2(1)). Regulation 6(1) requires manufacturers, authorised representatives and importers of containing products to ensure that light sources and separate control gears can be replaced with commonly available tools and without permanent damage to the containing product. Paragraph (2) lifts that where a technical justification is given in the technical documentation, and paragraphs (4) to (6) require information about replaceability on a public website, and on the packaging and in the instructions of products sold directly to end users, and dismantling instructions for end of life. We read the revised text on legislation.gov.uk on 5 November 2026.

Fitted wardrobes, shelving and panelling are not named, and what we read does not say whether building a lit cabinet into a room changes the answer, or who the 'manufacturer' of a bespoke piece is. We do not claim the Regulations apply to fixed joinery, or that they do not. The safe specification is the same either way: design for replacement.

Design-for-replacement rules (practice, not a standard):

1. Fit strip in clip-in profiles with removable diffusers. Never bond a fixed panel or trim over a strip.
2. Put the driver outside the lit carcase in a ventilated compartment with a hatch, in the plinth, a top void or a side bay.
3. Join lengths with plug connectors at the hatch or at a reachable end. No soldered joint out of reach.
4. Leave a service loop of cable so that a strip or module can be drawn out and refitted.
5. Label each driver, circuit and strip run, with the model, batch and colour temperature.
6. Keep spares from the same batch, and put the drawing of cable routes and driver positions, with the data sheets, in the handover pack.

Failure points and how to design them out

Colour, moisture and handover

A strip is seen along its whole length, so a mismatch shows. Specify one batch per run, ask for the supplier's stated colour consistency (see the SDCM and binning entries in the terms), and keep a spare length from the same batch so that a repair matches. Choose the colour temperature with the finishes: the colour temperature sheet has the by-space ranges. Warm white is a colour temperature; how true colours look depends on colour rendering, so ask for the colour rendering index and R9 as well, not only the kelvin figure. Treat the tolerances in the wording as brackets to fill from the supplier's data, not as recommendations.

Moisture needs an IP rating suited to the place (see the IP and IK sheet and, near water, bathroom zones). The luminaire's own conformity papers are covered in luminaire conformity, and the data sheet to ask for in luminaire data sheet to demand.

All LED light sources and drivers to be replaceable with commonly available tools, without removing or damaging fixed joinery, panels or finishes. Strip to be fitted in clip-in profiles with removable diffusers; no strip to be bonded behind a fixed panel or trim. The supplier states in writing how each light source and driver is replaced, in line with regulation 6 of SI 2021/1095 where it applies.

Drivers located at [position, for example plinth or top void] in a ventilated compartment, reached through a hatch not smaller than [ ] mm by [ ] mm, fixed with [screws / magnets], not glued. Ventilation openings [ ] mm2 top and bottom. Each driver loaded to not more than [80] per cent of its rating. A switched spur or isolator within reach of the hatch.

Mains supply to each driver by [electrician] from [spur or isolator], installed, inspected and certified to BS 7671 [edition in force]. Low-voltage cable [type, size] sized so the voltage at the far end is not less than [ ] per cent of supply, within the strip's stated maximum run. Plug connectors at [hatch or reachable end]; no joint behind a fixed panel; cable clear of hinges and runners; service loop [ ] mm.

Strip, profiles and drivers suitable for fixing to [timber / wood-based board] and for the enclosure as drawn, as the supplier's data sheet states [mounting-surface classification, maximum ambient or case temperature, maximum power per metre for the profile]. Strip in an aluminium profile in thermal contact, fixed by [clips / screws], not by tape alone.

Strip for [area] from one batch per run, [2700] K, colour consistency not worse than [3] SDCM, colour rendering index not less than [90], R9 not less than [ ], as the data sheet shows. Spares: [10] per cent spare length of each strip type from the same batch and [ ] spare driver per type, with data sheets and a labelled drawing of driver and cable positions in the handover pack.

Standards and sources

• SI 2021/1095, Ecodesign (Lighting Products) Regulations 2021, regs 2(1) and 6: read 5 Nov 2026.
• Approved Document P, Electrical safety, Dwellings, 2013 edition (England): paras 1.1, 2.5, 2.7 to 2.9, 3.13; England, dwellings.
• IET Wiring Matters, Autumn 2008: Section 559, luminaires and lighting installations: BS 7671:2008; confirm current edition.
• US DOE / PNNL: Thermal Management of White LEDs (PNNL-SA-51901, Feb 2007): principle; figures are dated.
• BS 7671 and BS EN IEC 60598-1 (current editions): named only; not read.

Questions we are asked

Should I use LED strip or downlights in a bookcase or alcove?

Strip in a profile with a diffuser suits continuous lines such as shelf fronts, coves and reveals. Pucks or small downlights suit deep niches and glass shelves where light should land in pools. Choose by what the light falls on and whether the source may be seen, then draw the section so that either can be replaced.

Where does the LED driver go in fitted joinery?

Outside the lit carcase, in a ventilated compartment you can reach through a removable hatch, for example in the plinth or a top void, with a switched spur or isolator within reach. Do not bury it behind a fixed panel. Size the hatch from the driver's data sheet plus clearance for hands and tools.

Do LED strips get hot enough to matter in a timber cabinet?

They make heat that has to be conducted away, and a US Department of Energy fact sheet says too much shifts colour, cuts output and shortens life. Use an aluminium profile in thermal contact, do not seal a strip in insulating material and ask the supplier for its mounting-surface and temperature limits.

Can I stick LED strip straight onto timber?

It is the weakest option: there is little thermal path for the heat, the adhesive can fail and a stuck strip cannot be replaced without damage. A strip in a clip-in profile, fixed with clips or screws, is the safer specification.

How do I replace a failed LED strip in fitted furniture?

Only if it was designed for it: a profile with a removable diffuser, plug connectors at a reachable end, a service loop and a driver behind a hatch. Without them the joinery may have to be opened. Regulation 6 of SI 2021/1095 expects light sources and control gear in containing products to be replaceable with commonly available tools and without permanent damage, and names furniture containing light sources.

Why is the far end of my strip dimmer?

Voltage is lost along the strip's tracks, and more is lost the more current it carries. A 24 V strip carries half the current of a 12 V strip of the same power, so it loses less over a run. Shorten the run, feed it from both ends or use a higher voltage, and keep within the supplier's maximum run length.

Does lighting in joinery need an electrician?

The mains supply to the driver is fixed wiring and should be done by a competent electrician to BS 7671. In dwellings in England Approved Document P puts such work within Part P, notifiable only if it involves a new circuit or a special location. The low-voltage side is often installed with the joinery, but check with the electrician who certifies the installation.