How do you light a stairwell?

With light that picks out every tread and that can never go fully off. In a shared stairwell, lighting is not atmosphere but an escape route, and that sets different requirements from a home: more lux, light that is always available, and a switching arrangement that leaves nobody in the dark.

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How a stairwell differs from stairs at home

At home you know your own staircase. In a communal entrance, an office building or an apartment block, people walk who are there for the first time, often with a bag or a pushchair, and sometimes during a power cut.

For workplaces, EN 12464-1 names a figure of 100 lux on a staircase, the same requirement as for corridors and circulation areas. In a home that is not an obligation; in a building where people work it is a guideline you are held to.

A stair lighting module of 150 lumens does not reach those 100 lux on its own. It picks out the tread, but it does not light the stairwell.

Two layers, not one

In a stairwell you therefore work with two kinds of light at once.

General light provides the lux. That comes from the ceiling or the wall and lights the whole stairwell including the landings. Surface-mounted spotlights or wall lights suit that, and in a suspended ceiling above a landing an LED panel does too.

Tread light picks out the edge of every tread, so you see where your foot lands. That is what the Trevo is for. Why that stays necessary even with plenty of general light is in How does stair lighting work?

The mistake you see most often is a single lamp high in the stairwell. On paper it gives enough lux, but it puts every tread in the shadow of whoever is climbing the stairs.

Switching without leaving anyone in the dark

A stairwell with a push button and a timer is the classic solution, and also the source of most complaints: the light goes out while you are still on the third floor.

Three approaches that work better:

• Motion detectors per floor, so the light travels with you instead of counting down.
• Base lighting that is always on, topped up with brighter light on movement. The treads then stay visible even if the sensor misses you.
• Tread light continuous, general light on a sensor. A 1.5 watt module burning day and night costs next to nothing, and the stairwell is never fully dark.

With a motion detector, check that it is suitable for LED. An old detector designed for incandescent bulbs sometimes has a minimum load that a few 1.5 watt modules do not reach.

Which colour temperature

Neutral white. A stairwell is not a living room, and at 4000K you see contrast and colour differences better than at 2700K. The Trevo has a CCT switch that sets 3000K, 4000K or 6000K during installation.

The same setting everywhere, though. A stairwell where the bottom floor is warmer than the top looks messy, and in a long shaft that stands out all the more. What the settings mean is in What light colour is 4000K?

What to watch in the execution

Access. A fixture high in a stairwell is not something you replace on a whim. Choose something with a long stated lifespan there, or hang it where you can reach it.

IP rating. An open entrance or an outdoor staircase calls for a sealed fixture. Our stair lighting is IP20 and therefore for indoor use only. What the digits mean is in What is the difference between IP44 and IP65?

Who wires it. In a communal space the installation is a matter for the owner or the owners' association, not for a resident with a screwdriver. Have an electrician do it and keep the documentation.

The range is at stair lighting, and the positioning in Stair lighting in the riser or in the wall?