Relay Dimming FAQ


Isn’t Relay Dimming just another form of power line messaging?

Messages are communicated between the switch and the receiving module using the power line but it uses a much different method. The forms of power line messaging you may be familiar with – PLC, PPM, Spread Spectrum - are much different as they impose a signal on top of the 60hz power. The three forms of power line messaging mentioned all can have issues with noise or signal attenuation. Relay dimming has none of those problems. We have a technical note that goes into the differences between Relay Dimming and PLC, PPM, and Spread Spectrum.


Will Relay Dimming work with my fixture?

That’s a hard question to give a simple yes or no, but if we had only one choice it would be yes. At PCS we have tested with many of the most popular fixtures and LED drivers to see how it works with Relay Dimming. But there are many different fixtures and drivers, and no one can test with all of them. If you are starting a project that you think could use Relay Dimming, please contact PCS and we can arrange to test your fixture to ensure correct operation.


Do you have any recommendations for LED fixtures?

We recommend the Phillips EvoKit fixture. For economy jobs, we recommend fixtures from GlobalLux


Can I see a wiring diagram, please?

Of course!


Doesn't the relay in the switch wear out?

The relay is opened and closed at the zero crossing point in the power line cycle. What this means is that there is very little energy at the relay contact points when the connection is made or broken. This prevents damage to the relay contacts and significantly increases the lifetime of the relay beyond its rated lifetime - which is in itself a very long time.


Do I need more than one receiving module if my wall switch controls more than one fixture?

Yes. A receiving module needs to be installed in each fixture. Refer to the wiring diagram to see how they are connected to the LED driver and the power line in each fixture.


Is there a 277V model available?

Yes. There are separate WS models for 120 VAC and 277 VAC. . The RM-0-10V receiving module is universal and operates at either 120V, or 277V.


I hear "clicking" from the wall switch when I control it. Is that normal?

Yes. The clicking you hear is the relay opening and closing that is the message being sent to the receiving module. It is perfectly normal.


Can I set the maximum ON level if the LEDs are too bright?

Yes, Simply turn on the lights - tap the top rocker - then adjust the light level that you want. Next time you turn the light on it will return to that level. If the lights are on and you tap the top rocker again, the fixture will go to 100%. You can also configure the double-tap levels as well.


Can I change the levels that the switch goes to when I double-click the top or bottom rocker?

Yes, these levels are configurable. Simply adjust the dimmer to the desired level, then tap the rocker (top or bottom depending on which double-tap level you want to set) 10 times, (the LED will start blinking) and then tap the rocker  (top or bottom depending on which double-tap level you want to set) 2 times. The new "double-tap" level will be set to the current level.


How does the WS work with an occupancy sensor?

The WS wall switch can work with an occupancy sensor. Wire the output of the occupancy sensor – typically a red wire – to the blue wire of the WS wall switch. When the occupancy sensor is “ON” – the room is occupied – the fixtures controlled by the WS wall switch will be ON. When the occupancy sensor is “OFF” – the room is not occupied – the fixtures controlled by the WS wall switch will be OFF. For more information, see the wiring diagram for more information.


What is the blue wire on the WS use for and what do I connect it to?

The Blue wire is for connection of an occupancy sensor. Connect the output of the occupancy sensor to the blue wire of the WS wall switch. If no occupancy sensor is being used, connect the WS wall switch blue wire to line. See the wiring diagram for more information.


Title 24 does require dimming but what about the other parts like daylighting and auto off?

The Relay Dimming wall switch does what it does – controlling LED lighting on, off, and to any illumination level. It isn’t designed to be a complete solution to all Title 24 problems. The WS wall switch does offer a 2-hour auto off - part of Title-24 - that can be enabled. See the Wall switch user guide for step-by-step instructions. Many installations require all aspects of Title 24 but many do not. Inside offices in a building aren’t subject to daylighting considerations and, depending upon the size and number of the LED fixtures other aspects of Title 24 will not apply. Use Relay Dimming where it works and other solutions where it doesn’t.


Why not just use a low voltage wall switch? It is a solution that has worked for years.

Sure, you can use that, but you have to run low voltage wires from the switch to the fixture and depending upon the installation this can be easy or it can be hard. While it may be a solution you know, you will find that Relay Dimming is a cost effective solution.


What colors do the WS wall switch come in?

White, Light Almond, and Ivory. Other colors are available as a special order. Contact PCS for more information.