If you’ve ever replaced a downlight or LED strip and watched it flicker for no obvious reason, you know the feeling. I work in quality management at Signify (formerly Philips Lighting), and I’ve spent the last four years reviewing LED driver specs, returned samples, and field failure photos. Most problems trace back to one early decision: constant current vs constant voltage LED driver selection.
This checklist is for specifiers, electrical contractors, and facility managers doing retrofit work. It applies to downlight modules, linear strip fixtures, and track-mounted rows—especially when you’re mixing brands. In my current role, I review every fixture and driver spec before it reaches customers—roughly 400 SKUs a year. I’ve rejected about 12% of first deliveries in 2025, and driver mismatch is the most common reason. This list comes from that experience.
Start With the Correct Driver Type
Most buyers focus on wattage and lumens and completely miss the driver type. The label on the module usually says either “constant current” or “constant voltage.” If it says 24 VDC or 12 VDC, that’s a constant voltage product. If it says 350 mA or 700 mA, it’s a constant current product.
Constant current drivers output a fixed current and let the voltage settle within a defined range. Constant voltage drivers keep the voltage fixed and allow the load to determine the current. Mixing the two—for example, trying to power a 24 V strip with a 350 mA CC driver—is a reliable way to get flicker, dead LEDs, or smoke.
I call these “downlight strip” problems. They happen both in a row of small downlights and in a continuous strip installation. The symptom is similar: one section stays dark, or the whole row pulses. The fix starts with the same question: what does the LED actually need?
Why the Downlight Strip Test Is Different
Before you buy a replacement driver, find out where it lives. Some downlights have an integrated driver inside the fixture. Others are designed for a remote driver mounted in a junction box. A downlight strip—a linear arrangement of downlight modules or a continuous row of LED strip—adds another layer because voltage drop and current sharing become real factors.
Take a Feit downlight as an example. I’m not picking on Feit; they make a lot of solid consumer fixtures. But if you open a Feit downlight and assume any driver with the same wattage will work, you’re guessing. The LED module inside may need a specific constant current. If the replacement driver’s current is higher, the module runs hotter and loses life. If it’s lower, you get dimmer output. That’s why the module spec sheet matters more than the fixture brand name.
If you follow Signify lighting news December 2025, you’ll see a lot of connected driver and system announcements. That’s exactly why this checklist still matters. New drivers add features like wireless control and sensor integration, but they still require the correct CC/CV match and control protocol.
Step-by-Step Quality Checklist
Step 1: Record the Module’s Required Current or Voltage
Find the LED module datasheet. If it’s a downlight module, look for a line like “rated current: 350 mA” or “700 mA.” If it’s an LED strip, look for “12 VDC” or “24 VDC.” Write this down in your request for quote. Do not rely on the old fixture’s driver label; in retrofits, previous drivers are sometimes the wrong ones.
Step 2: Match the Driver Output Range to the Load
A constant current driver will have a current rating and a voltage range. For example, a 700 mA driver with a 10–42 V output range works with modules whose total forward voltage falls inside that window. A constant voltage driver is usually simpler: pick 12 V or 24 V and make sure the driver’s wattage rating is at least 20% above the strip load.
This is the point where “good enough” fails. When I first started reviewing specs, I assumed any 700 mA driver would work with any 700 mA module. Three field failures later—or rather, three avoidable field failures—I learned to check the voltage range, thermal environment, and wiring distance before approving a sample.
Step 3: Define the Control Interface Before You Order
This is the step most buyers ignore. A driver can be constant current and dimmable, but if the control system is 0-10 V and the driver accepts only DALI, you have a compatibility problem before you turn the lights on.
When I compared two drivers side by side—same LED strip, same lumen output, same wiring diagram—the only difference was the control protocol. At 100% brightness, both looked fine. At 5% brightness, one was stable and the other stuttered. That contrast changed our spec template. Now we require the driver manufacturer to state the control protocol in the quote. Trust me on this one: control compatibility is way more than a checkbox.
Step 4: Check Voltage Drop and Ambient Temperature
The assumption is that a 24 V strip works fine if the driver wattage is high enough. The reality is that voltage drop along the strip changes the current balance. Long runs need shorter segments or heavier wire. For downlights, the common mistake is ignoring the driver’s thermal derating curve. A driver rated for 700 mA at 25°C may not deliver the same current at 50°C in a closed ceiling cavity.
In Q1 2024, that issue cost us a $22,000 redo—or somewhere close to that; the exact number is buried in a purchase order. We received a batch of 150 drivers that looked right on paper. After a heat test, 12% failed to maintain current at 60°C. The vendor claimed they were “within industry standard,” but our acceptance criteria said otherwise. We rejected the batch, and the vendor replaced it at their cost. Now every contract includes a thermal test requirement.
Step 5: Ask What’s Not Included in the Driver Price
I’ve learned to ask “what’s not included” before “what’s the price.” A low quoted driver price often excludes connectors, mounting brackets, control cables, programming fees, or commissioning time. The vendor who lists those costs upfront—even if the total looks higher—usually costs less in the end.
That transparency matters in B2B lighting more than people expect. A $500 difference on a driver quote can turn into a $5,000 difference at the job site if the installer has to chase missing components.
Final Inspection Points
Before you approve a driver sample, check three things:
- Does the driver output match the LED module’s constant current or constant voltage requirement?
- Does the driver’s dimming or control input match the project’s control system?
- Does the driver’s temperature derating match the real installation location?
If you can answer all three with a document, not a promise, you’re ahead of most retrofit projects. That is the whole checklist. The technology changes—especially with Signify’s connected lighting updates—but the verification habit does not.