What is 0-10V Dimming?
By Shoplight Solutions, Ted Schaefer
Triac dimming is a type of semi-conductor chip that is used for dimming incandescent lights. However, it is not suitable for CFL and LED lights although some lower wattage LED lights are beginning to support it. An industrial/commercial standard of dimming, 0-10V, originally developed for florescent fixtures, is beginning to make its way into residential lighting. For instance, if you are looking at dimming LED panels, you will probably find that 0-10V dimming is your only option.
0-10V dimming fixtures have a power supply that has 2 additional wires, most often violet and gray. If these wires do not touch and you measure the voltage across them, you will find that it is 10VDC (direct current) and your fixture will be at full illumination. However, if you touch these wires together, shorting them, then your fixture will go dark. If you use a resistor to adjust the DC voltage to 5V, then your fixture will product 50% intensity.
To control this voltage across the violet and gray wires at the fixture, you need a corresponding wall switch that also has both the on/off switching and a slider that operates its own set of violet and gray wires. A typical 0-10V switch is shown at the right. It operates as both single pole and 3-way. Naturally they are more expensive than other dimmers, ranging from $45-$60. Also, you will need to run a separate set of 18-gauge control wires from the fixture(s) to the wall switch. In a retrofit, this can be difficult. You can separate the dimming function to a separate dimmer or use remote control.
An incandescent bulb will dim to almost no output – very dim. Generally, LED fixtures have a cut off at about 10-20%. Because our eyes adjust to lower light, 10% is perceived as 32% brightness in scientific studies. For most applications, this 10-20% level is good.
0-10V dimming is not suitable for RGB color LEDs if you want to control each color independently. Look to DMX.
Below is a single pole diagram using the switch above. You can see the Violet and gray wires that run from the fixture back to the switch. If there is more than one fixture they are wired in parallel using these control wires. In other words, all of the violet wires are connected back to violet on the switch. Likewise, grays are connected together and routed back to the switch.