The video that started it
Last spring, around the middle of April 2024, a project manager sent me a video of a lobby chandelier that wouldn't stop cycling. It was an oval chandelier, maybe five feet long and two feet tall, hanging over a seating area in a boutique hotel. In the video, the LEDs would ramp up, stay on for a few seconds, then cut out. Stay dark for a few seconds, then ramp up again. It looked like someone was resetting the breaker every ten seconds. The message simply said: please tell me you know what this is.
I work in quality review for commercial lighting, which means I approve or reject product submittals before they reach the field. I also get pulled into problems after installation, particularly when a fixture and its control system don't play well together. This chandelier sat in the middle of a project that specified Acuity Brands lighting controls, DTL photocontrols, and FCOB LED strip. Untangling it took longer than it should have.
DTL photocontrols aren't dimmers
The first clue was in the project's fixture schedule. The oval chandelier was listed with a note: dark to light control. That phrase can mean different things to different people. In this case, the engineer's intention was probably: when the space gets dark, turn the chandelier on. But the electrical contractor read it as product terminology and searched for DTL Acuity Brands photocontrols dark to light. That type of photocontrol is an outdoor sensor. It switches power based on ambient daylight. It is not a dimmer and it doesn't belong on an indoor decorative fixture.
Here's something vendors won't tell you: DTL is easily misread because dark to light sounds like a dimming curve or an architectural lighting scene. It's actually a photocell switch. The DTL family from Acuity is designed to mount on exterior luminaires, wall packs, and area lights. At dusk, the sensor closes and the fixture comes on. At dawn, the sensor opens and the fixture goes off. That's it. There is no scene control, no timeclock scheduling, and no 0-10V dimming.
The DTL on our oval chandelier had been mounted on a small stem below the canopy. The sensor wasn't seeing the sky; it was seeing the chandelier's own light. The fixture would come on, the sensor would see light, open the circuit, and shut the fixture down. Then the sensor would darken, close the circuit, and restart the cycle. The built-in delay kept it from becoming a strobe, but the blinking was clear enough to send me that video.
We were using the same words but meaning different things. The engineer meant turn the chandelier on after dark. The manufacturer heard specify a dark-to-light photocontrol. Nobody caught it until the fixture was already in the air.
The fix wasn't complex. We removed the DTL and made the chandelier a switched and dimmed load on the Acuity Brands lighting controls network. If the owner truly needed the chandelier to respond to daylight, the right device would be a ceiling mounted photosensor connected to the lighting controls, not a line-voltage photocontrol clipped onto the fixture.
What is FCOB LED strip and why it mattered
While the controls were being corrected, I asked the factory to send a sample of the LED strip. The submittal called out FCOB LED strip. The sample under review looked like standard SMD strip with visible dots. The PM asked a question I see often: what is fcob led strip? It matters in this application.
FCOB stands for flip chip on board. Many small LED chips are mounted directly onto the flexible circuit board, then covered with a uniform phosphor layer. Instead of a row of individual dots, you get a continuous band of light. On an oval chandelier with a curved acrylic lens, that continuity matters. With a standard SMD strip, the fixture looks like a dotted line through the lens, especially if the lens is clear or only lightly frosted. FCOB was specified so the chandelier would look like a smooth line of light, not a row of LED spots.
But there is another part of the answer. FCOB strip is not a control technology. An LED strip doesn't dim by itself. Dimming happens in the driver. The first chandelier we received had a fixed-output driver, so the Acuity Brands lighting controls system could never dim it, even if the strip itself was correct. We had to order a replacement driver with a 0-10V dimming interface and make sure the control wiring was carried all the way to the fixture.
Chandelier install: where the education happened
The most frustrating part happened later, during the chandelier install. A technician tried to shorten an FCOB run on site. The cut wasn't on a marked cutting line, and it killed the last segment of the strip. That's a small thing if you know the strip. It's a big thing when the fixture is already five feet in the air and wrapped around a metal oval frame.
I should add that the chandelier install itself was never the real issue. Hanging and leveling an oval chandelier is standard electrical work. What isn't standard is integrating that fixture with lighting controls. The installer needs to know where the driver lives, whether the control wires reach the fixture, how the fixture connects to the 0-10V or network control circuit, and where the FCOB strip can be cut. Those details don't appear in a product photo. They belong in the spec and in the submittal review.
What I'd do differently
The lighting industry has changed. A decorative chandelier used to be a lamp holder with style. Now it's often a precision LED assembly with controls, dimming drivers, and custom strip light. What was best practice in 2020 may not apply in 2025. The fundamentals haven't changed: you need enough light, in the right color, without visible dots or glare. But the execution has changed.
Now I read every submittal looking for the words that are easy to skip. If the drawing says Acuity Brands lighting controls but doesn't list the driver, I ask for the driver model. If the fixture says FCOB LED strip, I ask for the strip specification and cut mark drawing. If the schedule says dark to light control on an indoor fixture, I change it before it becomes a problem.
There is something satisfying about sending a factory back to fix a chandelier when their submittal doesn't match. There is less satisfaction in explaining why a three-word phrase caused an eleven-week delay. The spec is where these problems are born, and the spec is where they can be killed.