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What the building code requires for stair lighting: 1 footcandle of brightness on every tread, a switch at each floor level on flights of six or more risers, and fixtures at exterior stair landings.
Most stair falls do not happen because the steps were built wrong. They happen because someone walked down a dark flight and missed a tread they could not see. Building codes treat stair lighting as a safety system: the International Residential Code (IRC) sets a minimum brightness, and the National Electrical Code (NEC) dictates where the switches go. Here is what both require in plain terms.
IRC Section R303.7 requires an artificial light source that illuminates the landings and treads of every interior stairway, with three conditions:
1. It must run on the building wiring. Battery puck lights and stick-on LEDs do not count as the primary source, because they can die quietly and leave the stair dark.
2. It must deliver at least 1 footcandle (11 lux) at the center of the treads and landings. One footcandle is modest, roughly a candle a foot away, but enough to read each tread edge. One 800-lumen LED fixture (a 60-watt equivalent) over a standard straight flight usually clears it; long or L-shaped flights often need a second source.
3. It must be switch-controlled from every floor level when the stairway has six or more risers.
The light itself has no riser minimum: even four or five steps need a wired source. Only the multi-level switch rule starts at six risers. To check your work, measure at the center of several treads, top, middle, and bottom. A phone light-meter app is close enough to confirm you are above 11 lux.
The IRC (E3903.3.1) and the NEC (210.70(A)(2)(c)) use identical wording: where lighting outlets are installed for an interior stairway, there must be a wall switch at each floor level, and at each landing level that includes an entryway, controlling the outlets, when the stairway between floor levels has six or more risers.
In practice: a normal flight between two floors needs a working switch at the top and at the bottom, both controlling the stair light. The standard method is a pair of three-way switches, plus a four-way for any intermediate landing with its own entryway, such as a door opening onto it. The code never says "three-way"; it only demands a switch at each required location that controls the light.
Two details catch people out. First, dimmers are restricted: these outlets must not use dimmers unless the dimmers give the full range of dimming control at each switch location. A dimmer at one end only does not comply. Second, automatic control is allowed: remote, central, or automatic control may replace the wall switches. A properly installed occupancy or motion sensor satisfies the switch rule, handy for basement and garage stairs.
Count risers, not treads: a flight with 13 treads has 14 risers, since the top landing surface counts as the last one. A typical 8-foot ceiling with 7.5-inch risers gives 13 risers, so nearly every full flight between floors needs switches at both ends.
The threshold matters for short connectors: steps into a sunken living room, garage entry steps, or porch steps with four or five risers. These still need the wired light under R303.7, but no switch at each level. Install one anyway; a three-way setup on a five-riser flight costs little and is the kind of detail inspectors and buyers notice. The IRC counts the whole run between floor levels, so on an L-shaped or U-shaped stair, the multi-level switch rule applies when the total between the two floors reaches six risers, even when each segment is shorter.
IRC Section R303.8 requires an artificial light source at the top landing of every exterior stairway, powered from the building wiring. One special case: exterior stairs giving access to a basement from grade level must have the light at the bottom landing instead, by the basement door, where the hazard is.
Mount a weather-rated fixture under the eave, on the soffit, or on the wall beside the top landing door, aimed down the flight. For basement areaway stairs, place it at the bottom near the door so whoever unlocks it can see every tread. Put the switch inside near the door, or use an outdoor-rated motion sensor so the light is on before anyone steps out.
A single ceiling fixture at the top of a long flight leaves the bottom treads in shadow; one at the bottom throws shadows upward. Plan so the full run is lit:
- Split long flights. Beyond about 12 treads, use two sources, for example a ceiling fixture over the upper half plus a sconce or step lights below.
- Recessed LED step lights give the most even coverage. Set them in the riser or wall just above tread level, every third or fourth tread. Sitting low, they wash each tread evenly and never glare.
- Wall sconces suit narrow enclosed wells. Mount about 5 feet above the nosings, staggered on alternating walls if the well is wide, so light rakes across the treads and defines each nosing.
- Cover the landings. The code measures landing centers too, and landings with doors are where people pause and turn. Give each landing its own source or ensure flight lighting spills onto it.
- Avoid glare. A bare bulb at eye level at the top can blind someone just enough to miss the first tread. Use diffused fixtures and one consistent color temperature (2700K to 3000K warm white).
Still planning the stair? Run the numbers with a stair lighting calculator and check the opening with a stair opening calculator. Correct geometry makes the lighting layout easy, since fixture positions follow the flight.
The automatic-control exception is genuinely useful. An occupancy sensor at the top and bottom, or one sensor with a wide field of view, can replace the three-way pair entirely, popular for basement, attic, and garage stairs where hands are often full.
Set the timeout to at least 5 to 10 minutes so the light never dies mid-flight, and position sensors to catch someone approaching the stair, not only someone on it. Keep a manual override at a customary switch location, since a failed sensor must not leave the only path between floors dark.
- Switch at only one end of a flight with six or more risers, the most common failure.
- Light wired to the breaker only, with no switch, common in unfinished basements. Add switches or an occupancy sensor.
- Dimmer without full-range control at each location.
- Battery puck lights as the primary source. Fine as accent over a wired source, never as the required illumination.
- Exterior stair with no fixture, or the fixture at the wrong landing on basement-access stairs.
- Burned-out bulb at final inspection. Walk the stair beforehand and confirm every required light works.
The code requires a wall switch at each floor level controlling the stair lighting when the flight has six or more risers (NEC 210.70(A)(2)(c), IRC E3903.3.1). It never says "three-way," but a three-way pair is the standard way to comply. Add a four-way for any intermediate landing with an entryway.
Yes. Both codes explicitly permit remote, central, or automatic control instead of wall switches. An occupancy sensor that reliably lights the full flight, with a sensible timeout, satisfies the requirement. Many electricians still add three-way switches as backup, which is good practice.
At least 1 footcandle (11 lux) at the center of every tread and landing (IRC R303.7). That is a minimum, not a target. Brighter, even lighting with well-defined tread edges is safer and looks better.
No, the multi-level switch rule starts at six risers. The flight still needs a wired light source under IRC R303.7, and most electricians recommend switches at both ends anyway. The extra cost is small.
At the top landing (IRC R303.8). Exception: exterior stairs leading down to a basement from grade need the light at the bottom landing, by the basement door. Use weather-rated fixtures.
Only if the dimmers give the full range of dimming control at each switch location. A dimmer at one end with a simple on/off companion at the other does not comply. When in doubt, use standard switching or automatic control.
Stair lighting code is short and easy to satisfy: a wired source delivering at least 1 footcandle on every tread and landing, a switch at each floor level on flights of six or more risers, and a fixture at the top landing of exterior stairs.
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