Adjacent LED fixtures where the dim levels are very different at 10%

Hi All,

I’m working with a Lutron lighting system for a house that has 800 feet of LED. Each LED section is 6 feet and line the ceiling in all the rooms. The gentleman doing the programming for the lighting system is having a problem with adjacent LED fixtures where the dim levels are very different at 10%. We are using forward phase dimming through an RPM-4A dimming module. It's not that it is not dimming to 10%. It is that 10% looks different on adjacent Linear LED runs. The keypad controls are all low voltage separate from the 120V switch leg. The Lutron RPM-4A dimming module feed the QTran power supplies which feed the Linear LED strips. All of the QTran power supplies are using the same Tap. When he send’s a command to multiple LED switch legs to dim to 10%, the light output on adjacent LEDs is very different. Same Tap, Same dim level, different results. No error codes showing up on the Lutron RPM-4A dimming modules


We have tested the same exact Lutron system in our shop with 4 sections 8 feet long and it dims fine and equal. The power supply company has also tested the same system in their office with no problems.
The power supply company and the Lutron programmer are all blaming the LEDs. We have replaced a few and this does not fix the dimming issue.

The products they are using are as follows:
HW-QS processor
SeeTouch keypads
RPM-4A dimming module
QTran power supplies-QTM-DC+CAP 60 watt/100 watt/200 watt
http://www.q-tran.com/products/power-supply/qtm-dccap

Thanks in advance.

Shine On LED

Hello ShineOnLED,

It might be the LEDs themselves, however it could also come down to how they were installed. Below are some questions that could help determine if the root cause is the LED or the installation.

•How far are the LEDs mounted from the power supply?

•What gauge wire has been installed between the power supply and LEDs?

•Are you getting different light levels from a run of LEDs connected to the same power supply?

•If so look at page 7 and 8 of the following link: http://www.lutron.com/TechnicalDocum...591.pdf#page=7

•If not and the light levels are uniform on the entire run, are the light levels varying between different power supplies/LED runs?

•If so, you could control one power supply per channel of the RPM-4A module and adjust the low end trim of each channel to match.

Please let me know if you have any questions.