Dim-to-off on horticultural lights


LED grow lights most often utilize a 0-10V analog wiring interface to receive dimming signals from lighting controls. These dimming interfaces are built into the LED driver (pictured below) and connect to a lighting control system, which then sets a control voltage on the 0-10V dimming line; the driver in turn senses this voltage and sets the LED driver output appropriately in response. Modern high power LED drivers used in the horticultural lighting industry utilize an additional feature - dim-to-off to shut the power supply down and turn the LEDs off entirely. 

An Inventronics LED power supply

How does dim-to-off work?

Dim-to-off is not an industry wide feature, and therefore it is often implemented differently across power supply manufacturers. For most manufacturers, the power supply is designed to shut the output down when the 0-10V control voltage is set to 0.5V or less; for some manufacturers, this lower limit is 1V. The diagram below shows the dimming response curve for an Inventronics driver, which is commonly used in horticulture:

Inventronics 0-10V dimming curve

How dim-to-off saves capital costs

Conventional lighting without dim-to-off requires that growers and integrators to eliminate mains AC controls that disconnect lights from AC power to turn lights off. This is most often done with contactor panels in large commercial grow facilities (pictured below). Smaller grow facilities may use plug in timers or relay boxes designed to turn off grow lights. For larger facilities, contactor panels for horticultural lighting may reach hundreds of thousands of dollars and can add months of engineering and installation to a project timeline. 

Contactor panels in a commercial greenhouse



Some 0-10V dimmable lights don't dim-to-off

While dim-to-off is a relatively new feature, only being built to most high power LED drivers in the last several years, 0-10v lighting controls are not new. 0-10V controls have been in use for decades in the general lighting industry, and have most often been used in conjunction with light switches or switched AC circuits to turn lights off. Most conventional 0-10V lighting products from the general illumination industry and 0-10V lighting controllers do not support dim-to-off, so it is important to verify that your lights and controllers support dim-to-off before making a purchasing decision. All GrowFlux lighting control products support dim-to-off. 

Some lights that are marketed with 1-10V control, which most often means that the lights do not dim-to-off. However, just because a light indicates support for 0-10V dimming, this does not necessarily mean that the light supports dim-to-off. The lighting manufacturer must explicitly state that the lights support dim-to-off. 


Most grow light controllers can't reliably dim-to-off

Since there is no unifying industry standard around 0-10V control, controls providers and lighting manufacturers have not managed to make the process of pairing up lights and controls easy. Most often, growers have trouble with dim-to-off once 10 or more lights are added to a single wired 0-10v dimming interface, resulting in unpredictable behavior. 


GrowFlux's Universal Dimmer features enhanced support for dim-to-off lights

GrowFlux's Universal Dimmer is designed to support the widest range of horticultural lighting manufacturers, and includes control circuitry and software that intelligently manages the 0-10V interface, ensuring that your lights always turn off when directed. The Universal Dimmer can reliably dim-to-off up to 50 lights on a single 0-10V interface. 

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