Cooper RF9540 dimmer lights unstable at ~90% bright point

Other Devices & Integrations Lighting & Load Control
#1

Hello, I have 3 Cooper RF9540 dimmers at my house, they all control LED ceiling can lights.
On one of them, my lights will be unstable at around 80-90% dim (typical led jitteriness). If I go above that or below that I am fine.

Any thoughts on the cause? Bad switch maybe, bad LED in the circuit? I have noticed this is my one Cooper that also has trouble with instant status, but it is also the farthest run from my Vera.

#2

[quote=“shallowearth, post:1, topic:187277”]Hello, I have 3 Cooper RF9540 dimmers at my house, they all control LED ceiling can lights.
On one of them, my lights will be unstable at around 80-90% dim (typical led jitteriness). If I go above that or below that I am fine.

Any thoughts on the cause? Bad switch maybe, bad LED in the circuit? I have noticed this is my one Cooper that also has trouble with instant status, but it is also the farthest run from my Vera.[/quote]

How well it’s connected to your Z-wave network is irrelevant to its dimming capabilities.

I use RF9540s in several places in my house. Every electronic dimmer is going to be hit or miss depending on the bulbs used.

Here’s my recent experience: I had three older Cree LED 60 watt-equivalent A19 bulbs in a dining room fixture controlled by a RF9540. It was too much light, so I repurposed those bulbs and put in three Cree LED 40-watt equivalent bulbs, which might be their newer model. Amount light is perfect now, but, there are several steps in the middle of the dimming range that will cause the lights to flicker. If I go above or below this middle range, lights are fine.

Now it’s possible that maybe with a different batch of these bulbs I could be fine again? Who knows. Maybe I’ll try removing one or two of the bulbs from the fixture to see if the varying the electrical load makes a difference (shouldn’t since these are neutral wire dimmers).

#3

OK, I figured out what is going on sort of. I have three dimmers, that must be on the same circuit. If I dim one of the first two in the line, than the third becomes unstable, not sure why it would do that, but it is super annoying. Any thoughts on that?

#4

If they are being fed by the same circuit from your breaker panel, and one becomes unstable when the other two are dimmed, there’s one of two possibilities:

A) The third is bad.
B) More than likely, you have a wiring issue. It almost sounds like each dimmer and fixture combo doesn’t have a dedicated neutral or primary wire that ties back into the main circuit feed junction box.

#5

Well the switch isn’t bad, because I swapped with another one to test that theory earlier :slight_smile:

Neutrals was my next guess too. But one of my dimmers (not even a z-wave just a two wire Lutron LED rated wall dimmer) doesn’t have a neutral, yet dimming that one can also cause the freak out down the line. But I am guessing that LED fixture itself might be causing issues on the neutral line that you might only see downstream.

So usually there are a bundle of neutrals (white wires) in the box and I just tie in the switches to those. Do I need to be teasing something apart? For example if there are 4 neutrals in a two gang box, do I need to separate them into 2 pairs then tie into them that way? Does that even gain me anything? Or would there usually only be 3 wires in a bundle in that case (one from the loop for each switch and one to take it all back to the circuit breaker).

#6

The proper (modern NEC code in America) wiring should be a 2/1 conductor (Black, White, Green/Ground) feeding the junction box.

Then for every separately controlled fixture, there should be 2/1 conductor ran into the box from the fixture.

So let’s say you have three fixtures controlled from that one junction box, that means you should have a total of 4 black, 4 white, and 4 ground wires. This doesn’t include any pigtail/jumper wiring that was done inside the box to distribute the hots to the various switches.

As long as all the neutrals are electrically joined inside the box it doesn’t matter how (as long as it meets code in terms of wire nuts and wire gauge sizing). Sometimes bundles get too large for one wire nut and have to be split.

Using switches like the Coopers (and most Zwave ones) complicates things since they have their own pigtails coming out of them (instead of terminal screws), that increase the wire bundle sizes even more. I’ve had 4 gang boxes that were a nightmare to fit everything inside. I’ve had to remove the previous old switches and undo the bundles because the previous installers method wouldn’t work because of the additional pigtails the zwave switches introduce. YOu might want to think about that, it also gives you a chance to volt and ohm test everything to identify what’s going where.