A Quality Inspector’s 6‑Step Checklist for Specifying Smart Lighting: Stair Lights, Occupancy Sensors, Zigbee Dimming & a Note on Grow Lights

Who This Checklist Is For

If you’re specifying lighting controls for a commercial build, a multi‑family development, or even a large renovation, you’ve probably stared at a page full of options and thought: “Which combination actually works without calling me back in six months?”

I’m a quality compliance manager in lighting. I review every delivery before it reaches the contractor — roughly 200 items a year. Over four years I’ve rejected about 18% of first shipments because specs didn’t match what was promised. Not because the vendors are bad, but because the chain from spec to installation has too many places for a mismatch to slip in.

This checklist covers the six areas I check every time. It’s built around typical projects I see: smart stair lights, occupancy sensors, Zigbee‑connected dimming, and the occasional question about grow lights vs. regular bulbs (yes, that comes up more often than you’d think).

Step 1: Map the Space to the Lighting Task

Before you pick a Legrand occupancy sensor switch or a dimmer, ask: what is this room actually used for?

• Stairwells / corridors — need consistent illumination, often with step‑lighting. Here the Legrand stair lights series (under‑cabinet or wall‑mounted) works well because they are rated for continuous operation and have a low profile. I’ve seen contractors try to use standard recessed step lights; the failure rate on vibration and moisture in stairwells was 12% in one building we audited.
• Offices / meeting rooms — need occupancy‑based control. An occupancy sensor switch (like Legrand’s radiant or adorne series) should have both PIR and ultrasonic detection for open‑plan areas. I’ve rejected switches that only had passive infrared because they missed movement behind partitions.
• Plant rooms / storage — a simple vacancy sensor is fine. Don’t waste money on Zigbee dimming if the light is only on for 10 minutes a day.
• Greenhouses / indoor farms — this is where how is a grow light different from a regular bulb matters. A grow light emits specific PAR (photosynthetic active radiation) wavelengths, usually weighted toward blue and red. A regular LED bulb is designed for human vision (Color Rendering Index > 80) and will starve your plants. As of Q1 2025, the industry standard for grow lights is PPFD (photosynthetic photon flux density) rather than lumens.

I’m not a botanist, so I can’t tell you the exact PPFD for tomatoes. What I can tell you from a compliance perspective: if a project lists “grow light” but the spec sheet shows only CCT and CRI, it’s wrong. We rejected a batch of 80 fixtures last year because the vendor labeled them “grow light” but the spectral distribution was identical to a 3000K office bulb. That cost the client a $22,000 redo.

Step 2: Select the Right Occupancy / Vacancy Sensor

The Legrand occupancy sensor switch family comes in multiple detection patterns and load ratings. Here’s the short version of what I check:

• Coverage pattern — the spec sheet should show a floor‑plan diagram with the detection radius at 1.5m height. For a stairwell, you need a corridor‑shaped pattern, not a circle. Many standard sensors have a circular coverage that leaves the ends of a long staircase dark.
• Time delay options — minimum 30 seconds for vacancy, maximum 30 minutes for occupancy. If the delay is fixed at 15 minutes, you’ll have lights on in empty rooms for too long — a waste of energy. We once had a client complain that the occupancy sensor switch in their restrooms kept the lights on for 20 minutes after someone left; the spec didn’t specify adjustable delay.
• Neutral wire requirement — most Legrand occupancy sensors require a neutral. If the building was wired switch‑loop only, you need a special version or a smart relay. Check before ordering. About 10% of our rejections in 2024 were because the sensor ordered was for a neutral‑less setup but the job site had neutrals (or vice versa).

Step 3: Verify Zigbee Compatibility (Don’t Assume “Zigbee” Means Interoperable)

Zigbee connect and Zigbee dimming are two different things. I see this confusion every quarter.

• Zigbee connect means the device can join a Zigbee network and communicate with a coordinator (hub). But it doesn’t guarantee that it follows the same application profile. For example, a dimmer using the Zigbee Light Link profile won’t talk to a sensor using the Zigbee HA (Home Automation) profile unless the coordinator supports bridging. Legrand’s IoT ecosystem uses Zigbee 3.0 and Matter, which helps, but I still check the certification logo on the box. As of January 2025, Zigbee 3.0 certified devices carry a specific mark. If the product says “Zigbee compatible” without the 3.0 logo, I flag it.
• Zigbee dimming — the dimmer must support the same dimming protocol (phase‑cut, 0‑10V, or DALI) that your LED driver expects. Many people assume “Zigbee dimming” automatically does phase‑cut. Actually, Zigbee is just the communication; the dimming method is a separate choice. Legrand offers both phase‑cut and 0‑10V modules. I’ve rejected a shipment of 50 dimmers because the spec said “Zigbee dimming” but the actual device was a relay (on/off only).

The surprise wasn’t the technology gap. It was how many specifiers assumed that “Zigbee” implied “works with everything.” Never expected a $4,000 order to be useless because the bridge didn’t support the profile. Now every contract includes a line: “All Zigbee devices must be Zigbee 3.0 certified and tested with the project gateway before shipping.”

Step 4: Check Dimming Compatibility with LED Loads

Zigbee dimming can be smooth or flickery depending on the pairing. Here’s my practical check:

• Minimum load — most Legrand dimmers have a minimum load of 10–25W. If you’re using a 4W LED strip, you’ll need a low‑load dimmer. I’ve seen installations where only three out of ten dimmers worked because the LED load was below the minimum.
• Flicker — ask for a photometric test report showing the flicker index (< 0.1 recommended) and percent flicker (< 5%). Many cheap LEDs flicker at low dimming levels even with a good Zigbee dimmer. We run a simple test during quality inspection: dim from 100% to 1% and video at 240 fps. If we see pulses, the combination is rejected.
• Noise — dimmers can emit a buzzing sound when paired with certain LED drivers. I’ve rejected batches for audible buzz at 50% brightness. The fix is usually a driver with a higher PWM frequency (above 1 kHz).

Step 5: Special Considerations for Stair Lights

Legrand stair lights (often part of the under‑cabinet line or the Halo series) need attention because of voltage drop and moisture.

• Voltage drop — if you’re running a daisy‑chain of stair lights more than 10 metres, you need to calculate the voltage drop. I’ve seen installations where the last step light was 30% dimmer than the first. The solution: parallel wiring or a larger gauge conductor. Legrand provides a calculator in their spec sheet; use it.
• IP rating — stairwells can be dusty and sometimes damp (cleaning, condensation). I specify a minimum IP44 for surface‑mounted step lights. A contractor once installed IP20 lights in a stairwell that had a cleaning schedule twice a day; the moisture killed three units within three months.
• Emergency backup — if the stairwell is a fire escape route, the lights must stay on during power loss. Many stair lights are not rated for emergency use. Check the UL listing. Legrand has a specific emergency‑rated version for stairways.

Step 6: Don’t Forget the Grow Light Question (Even If It’s Not on Your Spec)

I get asked at least once per quarter: “How is a grow light different from a regular bulb?” — and it often comes from a project manager who’s sourcing lights for a plant room or a break‑room herb garden. Here’s the short answer from a quality perspective:

• Spectral output — grow lights have a peak in the blue (~450 nm) and red (~660 nm) regions. Regular bulbs are designed for smooth spectrum across the visible range (400–700 nm) to render colors well. A regular bulb’s light is mostly useless for photosynthesis because the energy is distributed across the whole spectrum instead of concentrated where plants need it.
• Measurement units — regular bulbs are rated in lumens (human visual perception). Grow lights are rated in PPF (μmol/s) or PPFD (μmol/m²/s). If a product claims to be both a grow light and a regular bulb, check which metric is on the datasheet. I rejected a product once that listed “10,000 lumens” and called itself a grow light — the vendor couldn’t provide a PPF figure.
• Heat — many grow lights produce more heat than regular LEDs because they operate at higher current to push the peak wavelengths. That means the thermal management is different. For a Legrand lighting control system, if you’re dimming a grow light, you need a driver that handles the heat load without thermal derating. I’ve seen dimmers overheat when used with grow lights because the load was actually higher than the nominal wattage.

My experience is based on reviewing about 30 projects that included grow‑light zones over the last four years. If you’re working with vertical farms or commercial cannabis, your requirements will be far more stringent — I’d recommend consulting a horticultural lighting engineer. From a quality control standpoint, the main takeaway is: never treat a grow light like a regular LED when specifying controls.

Common Mistakes & Final Tips

• Mistake #1: Over‑specifying occupancy sensors for stairwells. A stairwell usually has transient traffic; an occupancy sensor that holds the lights on for 10 minutes wastes energy. Use a vacancy (manual‑on) sensor with a short time delay, or a combination with photocell.
• Mistake #2: Assuming all Zigbee dimmers are forward‑phase. Check the data sheet: Legrand Zigbee dimmers can be either forward‑phase or reverse‑phase. Reverse‑phase is recommended for LED loads because it reduces inrush current. I’ve rejected shipments where the dimmer was forward‑phase and the LED drivers required reverse‑phase.
• Mistake #3: Forgetting to test the system end‑to‑end before installation. I run a bench test: one dimmer, one sensor, one LED load, and the Legrand Zigbee bridge. If the sensor can’t trigger the dimmer over the network, we fix it before 200 units go up the wall.
• Cost vs. reliability: Switching to a verified Zigbee occupancy sensor switch with adjustable delay and a neutral requirement increased our per‑unit cost by about $12. On a 500‑unit project that’s $6,000 upfront — but we eliminated the rework calls. The ROI was positive within the first year.

— Quality Inspector, Legrand compliance team. Based on Q1 2025 reviews at a 50‑,000‑unit annual order volume.