Who Specifies the Driver?
By C. “Webster” Marsh
I’ve seen a wide spectrum of approaches to specifying luminaires. Sometimes the specification is little more than a narrative description paired with a preferred manufacturer. Other times it drills all the way down to an exact catalog number, delivered lumens, efficacy, TM-30 metrics, and L70 projections. Both approaches have their merits depending on the project, budget, and delivery method. But there is one sticking point that most lighting designers, regardless of rigor, seem to stop short of specifying: the driver.
Why is this the case?
According to the IES definition of a luminaire, the driver is an integral component of the system. Whether it is neatly tucked inside a troffer or mounted remotely to power a short length of tape light, it is still part of the luminaire package. Yet in specifications, the driver is often treated as an afterthought or ignored entirely. We define the light-emitting components in great detail while the device that controls their behavior is described as “0–10V.”
Part of this stems from a lack of transparency on the manufacturing side. Many manufacturers will state that a luminaire includes a 0–10V driver, but stop short of identifying the driver manufacturer, model, or dimming performance. Some go above and beyond, clearly listing minimum dimming levels, dimming curves, flicker metrics, and compatibility. Others keep that information opaque.
One reason is flexibility.
On a large project, the ability to swap driver brands when inventory tightens can be the difference between meeting a schedule and missing it. From a supply-chain standpoint, that makes sense. From a design standpoint, it raises questions.
We already understand the visual consequences of inconsistency in LED packages. Anyone who has walked a project with mixed diode bins has seen color shifts of 200 Kelvin or more in worst-case scenarios. Driver performance introduces a similar, though often less obvious, variability. Different driver manufacturers implement 0–10V dimming differently. Response curves, low-end stability, dead travel, and dropout behavior all vary. This is one of the reasons many lighting designers zone controls by fixture type, attempting to avoid mixing dimming performance within a space. But what happens when the fixtures appear identical while the drivers inside are not? The result can be uneven light levels, flicker at low end, or illuminance variations that climb into the hundreds of lux, all within the same control zone.
The other contributor to this issue is philosophical.
Drivers are often framed as an “electrical thing,” something best left to engineers. Engineers are already responsible for circuiting, load balancing, voltage drop, and upstream power infrastructure so shouldn’t they also be specifying the drivers? In theory, perhaps. In practice, there’s a disconnect. If the engineer did not select the luminaire, how would they know which driver is most appropriate for it? The performance characteristics that matter most to occupants are smooth dimming, deep low-end control, and visual comfort. These are rarely the primary lens through which electrical systems are designed.
Take 0–10V dimming as an example. On paper, it sounds standardized. In reality, it encompasses a wide range of behaviors, from drivers that bottom out at 10% output to those capable of stable dimming down to 1% or even 0.1%. Choosing between those options is not simply a technical decision; it’s a design decision tied directly to the intent of the space. Expecting an engineer to intuit that intent without guidance places both disciplines in a difficult position.
So, the question remains: if the driver is part of the luminaire, and the luminaire is part of the lighting design, why do we so often stop short of specifying it? As lighting systems become more adaptive and more human-centric, the driver may prove to be less an electrical accessory and more a pivotal part of the experience itself.
About the author
C. “Webster” Marsh is a Lighting Controls Designer at Sladen Feinstein Integrated Lighting and as Education Manager for the Lighting Controls Academy.
A Certified Lighting Controls Practitioner (CLCP), Webster is also Director of Education and Programming for ArchLIGHT Summit, creator of Tonight in Controls, and he co-hosts the Lighting Controls Podcast, helping professionals stay connected with the latest in lighting controls.
