The short answer
- Light low, not high. Concealed light beneath benches, behind backrests and along bench edges is the most comfortable and the kindest to the fittings.
- The ceiling is the hottest place in the room. Anything mounted high must be rated for it. Harvia’s Cilindro manual, for example, requires electrical equipment more than 1000 mm above the floor to be approved for 125 °C (T125).
- Never above the heater, and never inside the heater’s published safety distances.
- Use fittings made for saunas, installed only where their own rating allows. A sauna LED strip rated to about 60 °C belongs under a bench, not along a cornice.
- Hide the source, show the surface. Light washing across timber looks better and causes less glare than a visible lamp.
- Plan lighting with the control. Most separate sauna controls can switch the lights.
- Steam rooms are different. They need fittings sealed for saturated air, with IP ratings set by the manufacturer.
Every fitting is selected for its location and installed by a licensed electrician to AS/NZS 3000 and the manufacturer’s instructions.
Why sauna lighting is different
A sauna is not just a warm room. It layers heat by height. Hot air rises off the heater and gathers under the ceiling, so the air under the ceiling is far hotter than the air near the floor. Our guide to how a sauna heats explains this layering, and it drives almost every lighting decision:
- Near the ceiling, temperatures are close to the heater’s working range. Light fittings, drivers and cables there face the most heat, for the longest time, every session.
- Above the heater is the hottest column of air in the room. It is also where the temperature sensor usually sits, so a light there both suffers and gets in the way.
- Low in the room, under the benches and near the floor, it is far cooler. Fittings last longer, and light from there falls where people need it: on steps, bench edges and the floor.
Why this matters: a fitting chosen for a living room may look fine on the first night and fail within months in a sauna. Heat ages plastics, seals, LEDs and drivers. Low placement is the main way to give lighting a long, trouble-free life.
Where light works
Beneath the benches
The classic position. A strip or small fitting tucked under the front edge of a bench throws light down onto the floor and across the step below. Harvia’s North American heater manuals say lights placed low last longer and describe under-bench positions as ideal. Harvia also shows LED strips along the bottom edge of the benches to pick out the different levels.
Why it works: the light source is hidden, the floor and steps are lit for safe movement, and the fitting sits in the coolest part of the room.
Behind the backrests
A backrest stood slightly off the wall leaves a slot for concealed light. The light washes up the wall behind the bather and gives the room a soft glow without any visible lamp. This is one of the positions recommended for sauna LED strips. Keep the fitting within its rated height, since backrests sit higher in the room than under-bench positions.
Behind panels and in recesses
Light can be built into the room’s joinery: behind a raised panel, in a recess or in a shadow line. This is where lighting becomes architectural, but each fitting must still suit the temperature at its height. Harvia warns that light protective covers fixed directly to the wall or ceiling may be a fire risk, so shades and diffusers should be products designed for the sauna, fitted as their instructions say.
Wall lights and shades
Purpose-made sauna lamps with timber shades are still widely used. Harvia, for example, makes an under-bench lampshade that spreads the light for a warm, soft glow. Where a wall-mounted sauna light is used, Harvia’s manuals ask that it not be placed over the heater or over the upper benches, and any fitting mounted high must be rated for the temperature at that height.
The ceiling
Ceilings are attractive places for light in other rooms, and the worst place in a sauna. Anything there faces the room’s highest temperatures. Where a ceiling effect is wanted, such as a starry sky, fibre optics are the usual answer because the fibres carry light without electronics (see below).
Around the heater
Some manufacturers offer illuminated guard rails or LED strips integrated into the bench beside the heater, so the light catches the steam as it rises off the stones. These are product systems designed for that position. Never improvise lighting near the heater: its published safety distances apply to every fitting, cable and shade.
The heater's clearances apply to lighting too
Each heater manual includes a safety-distance drawing for combustible materials. Light fittings, shades, cable runs and the timber that hides them all fall within it. The manual for the selected heater governs.
Fittings rated for the heat
What manufacturers ask for
Heater manufacturers set conditions for electrical items in the hot room, and they are model-specific. Some current examples:
- Harvia (Cilindro heater manual): cables more than 1000 mm above the floor, or inside the sauna walls, must withstand at least 170 °C under load. Electrical equipment mounted more than 1000 mm above the floor must be approved for 125 °C (marking T125).
- One European heater maker requires all electrical installations inside the cabin to suit at least 170 °C.
- Harvia’s sauna lamp used in its planning instructions is marked IP44 and ta 125 °C, and must be installed by an electrician.
These figures belong to those documents and products. They are not universal rules, and the heater manual for the room governs.
Why this matters: a fitting’s temperature rating has to match the hottest air it will sit in, not the room’s average. In a sauna, those two can be very different.
LED strips
Sauna LED strips are popular because they are slim, low-glare and easy to hide. They also have tight limits. One Harvia LED strip set is published with a maximum operating temperature of about 60 °C, a low maximum mounting height and a transformer housed in an IP44 enclosure kept low in the room. The heights published for different market versions of that kit vary, so the instructions supplied with the product govern.
Why this matters: 60 °C is far below the temperature near a sauna ceiling. An LED strip run along the top of the walls or around the ceiling, as some photos suggest, would be outside the rating Harvia publishes for its own strip. Ordinary household LED strips are not designed for saunas at all.
Fibre optics
Fibre-optic lighting separates the light from the electronics. A light source, or “projector”, drives a bundle of glass fibres, and only the fibre ends appear in the room. The fibres carry light, not electricity, so they can sit in positions too hot for an electrical fitting, such as a ceiling.
The light source still has limits. It sits either outside the room or low inside it, within its own rating. Harvia’s Luminous fibre sets for saunas, for example, have a power source rated IPX4 that can be installed in the sauna, rated for ambient temperatures from −25 to +80 °C, with fibres of about 2.4–3.6 m. Harvia’s steam-room fibre sets come with longer fibres, up to 10 m. Harvia says the light source should be replaced only by a professional.
Why it works: a starry ceiling or points of light in hot positions become possible, while the part that can fail stays somewhere cooler and reachable.
What we use
In the custom saunas we build, lighting is usually LED strip set in aluminium profiles, concealed at bench level or behind backrests and kept within the rating of the strip used. It is our own detailing rather than a Harvia lighting product; the Harvia figures above are quoted as published examples of the limits sauna lighting has to respect.
Glare and comfort
People in a sauna sit and lie still, often looking up or across the room. A bare lamp at eye level, or a strip that can be seen end-on from the top bench, quickly becomes uncomfortable.
- Conceal the source. Light should come from behind a bench lip, backrest or panel, so bathers see lit timber rather than the fitting.
- Think about every sightline, including lying on the top bench looking up, and looking back towards the door.
- Keep it dim. Saunas are at their best in low light. A dimmable system lets the room be brighter for cleaning and softer for bathing.
- Light the hazards. Steps, bench edges, the floor and the way out should always be visible. Harvia’s safety guidance notes that adequate lighting matters, particularly where children or older bathers use the sauna.
- Watch reflections. Glass doors and walls reflect concealed light back into the room. See our guide to sauna glass and doors.
Colour temperature
Most sauna lighting is warm white. Harvia publishes about 3000 K for its sauna fibre lights and LED strip sets. Warm light brings out the colour of timber such as western red cedar and suits a calm room. Cooler white light can make a sauna feel clinical.
Coloured or tunable lighting is available in some systems, mainly for commercial and spa settings. It is a matter of taste rather than a technical requirement.
Lighting and the sauna control
Separate sauna controls usually do more than run the heater. Harvia’s Xenio and Fenix controls, for example, have a lighting output, so the lights can come on with the sauna and be switched from the panel or the app.
- Why it helps: one panel for heat and light; lights that switch off with the sauna instead of being left on; and, in commercial rooms, a consistent setting for every session.
- What to check: the light load must suit the control’s rated output, the lighting must be compatible with the control (dimming in particular), and the transformer or driver must sit where its own rating allows.
Our guide to sauna controls explains control units, outputs and remote start.
Steam rooms are lit differently
A steam room is not as hot as a sauna, but its air is saturated and every surface is wet. The risk shifts from heat to moisture.
- Harvia asks that the suitability of each lighting type for humid conditions be confirmed, citing IP65, and uses fibre-optic lights on the ceiling and on the bench fronts so bathers can see where the floor ends and the benches begin.
- Some other manufacturers cite IP67, and at least one recommends extra-low-voltage lighting inside the room.
- Every fitting penetrates the room’s vapour-control layer and must be sealed into it.
- Fittings designed for pools may rely on being cooled by water, which a steam room does not provide.
The luminaire maker and the licensed electrician confirm the product, its rating and its position. Our guide to steam room design and construction covers the rest of the enclosure.
Lighting as architecture
Light shows off what has been built. Concealed light grazing along vertical timber, under a floating bench or behind a backrest reveals the grain and the joinery and makes the room seem larger. In a glass-fronted sauna, the interior lighting is also what people see from outside, so the sauna can become a lit feature of the bathroom, pool house or spa.
That only works if lighting is designed with the benches and joinery, not added at the end. Bench lips need to be deep enough to hide a strip; backrests need a gap behind them; cable routes, drivers and service access need planning before the lining goes on. On our custom saunas we use low, indirect light, often concealed beneath benches or behind backrests, with fittings rated for sauna temperatures. See custom saunas.
Electrical work
Sauna lighting must use fittings rated for their location, installed by a licensed electrician to AS/NZS 3000 and the manufacturer’s instructions. Saunas are a special location under the Wiring Rules, and the electrician confirms each product and position.
Common mistakes
| Mistake | Why it is a problem | Better approach |
|---|---|---|
| LED strip around the ceiling or top of the walls | Far hotter than many sauna strips are rated for | Run strips low, under benches or behind backrests, within the product’s rated height |
| Ordinary downlights in the sauna ceiling | Hottest position in the room; not designed for it | Fibre optics for ceiling effects, or a fitting rated for that height |
| A light above the heater | Hottest air; interferes with the sensor; inside the heater’s safety zone | Keep lights away from the heater, per its manual |
| Visible lamps at eye level | Glare for seated and lying bathers | Conceal the source; light the timber, not the eyes |
| Drivers or transformers hidden in the hot room | Electronics fail early in heat | Place them where their rating allows, often outside the room or low down |
| Lighting added after the joinery is designed | No space to hide fittings or route cables | Design lighting with benches, backrests and the control |
Questions to settle at design stage
- Which surfaces should be lit: floor, steps, bench edges, walls, ceiling?
- Where will each fitting sit, and what temperature is its rating for that height?
- Where will drivers, transformers or fibre light sources go, and can they be reached for service?
- Will the sauna control switch the lights, and is the lighting compatible with it?
- Is dimming wanted, and does the system support it?
- For a steam room, what IP rating does the luminaire maker specify, and how will each fitting be sealed?
If you are planning a sauna or steam room, talk to us about lighting early, while the benches and joinery are still on paper.