Maestro Dimmer Giving Me Fits!

Little Bill

Moderator
Staff member
Location
Tennessee NEC:2017
Occupation
Electrician
First let me apologize for the long post, but I don't know any way to shorten it much.:(

I have a customer that has a Maestro IR dimmer, (MIR-LFQMT-) that I installed about 6 months ago that stopped working. He asked me to look at it and told me something crazy sounding that it was doing. In case some are not familiar with this dimmer, I'll give a brief description of it.

It is a dimmer and fan control in one unit. It has a wall unit that replaces a wall switch. It also has a module that goes in the fan canopy. You don't need a neutral in the wall box. You just either wire it as a SP or 3-way, SP in my case. The module has four wires. One is black for power from the switched leg. The other wires are: red for the light, yellow for the fan, and white for neutral. It also has a remote to operate it. The wall unit has a top section (dimmer) and a bottom (fan) section. There are LED lights at each section to indicate the level you have it set at.

The problem is the dimmer stopped working. If you hit the button to dim/raise the light, the LEDs would just scroll up & down but no dimming took place. Now the crazy part I mentioned. He said he discovered that if he turned on another switch in the box the dimmer would work.:? I checked it and sure enough that was the case.

Here's what is in the 3-gang box where the wall unit is. The dimmer/fan control, a SP switch that isn't connected, (just a space filler), and a 3-way switch for the can lights in the room. Power comes into the box from a 14-2 NM cable. There is another 14-2 that I don't know where it goes, 14-3 to the fan/light, and 14-3 for the can lights. I'm only using two wires for the wall unit since the 3rd (red) wire was originally for controlling the fan/light separately, so it is capped off.

I checked the wiring and everything seemed ok. I reset the dimmer with a pullout service switch it has called a FASS. That didn't help, in fact the LEDs kept scrolling and finally just stopped. I called Lutron support and they had me do a factory reset. They said that if that didn't work they would send me a new unit. It didn't work and they sent a new unit.

When the new unit arrived, I checked all the wiring again then installed it. It did the same thing as the old one.:rant: So I turned on the 3-way for the can lights and it worked.
Just to add, once the lights are dimmed and fan running, if you turn off the 3-way it doesn't stop the fan or lights. So I decided to do a deeper check on everything. I first thought I would check voltage at the wall unit, it had 120V.

Just to rule out phantom voltage, I hooked a test light up that I have. It's just a light socket with pigtail leads. I connected one lead to the neutral in the box and one to the line side of wall unit. The test light lit and I had 120V, so I know the voltage was real.

Now in doing this, the 3-way for the can lights was not on. But I discovered that with the test light connected to the unit that it caused the dimmer to work correctly. So, it wasn't that the can lights had to be switched on, just a load paralleled with the unit made it work.

This sounded like maybe I had a bad neutral connection so I turned off the power to check everything. I took all the splices apart in the box, re-stripped them and put on new wire nuts. I also took the wires apart in the canopy. There is only the 14-3 at the ceiling, no splices. While I had this apart, I checked continuity with the neutrals and everything was fine. I put everything back and checked the unit again. Still wouldn't work without a load in parallel.

I completely disconnected the 3-way for the can lights and that didn't help. I hooked the test light back to the switch and the dimmer worked correctly. I even tied it both on the line side and load/switched side of the unit, either would allow the dimmer/fan control to work.

Ok, now I go back to the fan/light. I hooked my test light to the black wire that powers the module. It turned on my test light, so I know the power (120v) was getting to the ceiling. I also went to the wall unit while the test light was on and pulled out the service switch on the control and it turned off the test light, pushed it back in and turned the light back on. So I know the power is constant to the module. This was all done with no parallel load on, just power and neutral from the wall unit/box.

So I hooked the black wire back to the switched wire and disconnected the fan light from the red wire. I hooked my test light to the red wire and neutral. Then I tried the wall control again to see if it would dim the test light. It did not dim it either. So just to rule out the problem being in the ceiling light I connected the 3-way back up so I could get a parallel load. When I turned on the 3-way, it would then dim/raise my test light. So that ruled out any problem with the ceiling fan or light.

I got on the phone with Lutron and they didn't have an answer for me, other than a bad neutral which I ruled out already.

Anyone have any thoughts on why this thing worked for six months now it won't, even with a new unit?
 

Dennis Alwon

Moderator
Staff member
Location
Chapel Hill, NC
Occupation
Electrical Contractor
Bill I am confused here

It is a dimmer and fan control in one unit. It has a wall unit that replaces a wall switch. It also has a module that goes in the fan canopy. You don't need a neutral in the wall box. You just either wire it as a SP or 3-way, SP in my case. The module has four wires. One is black for power from the switched leg. The other wires are: red for the light, yellow for the fan, and white for neutral. It also has a remote to operate it. The wall unit has a top section (dimmer) and a bottom (fan) section. There are LED lights at each section to indicate the level you have it set at.
The black bold--If the switch has a neutral then it must be in the switch box.... No.

The red bold-- black on the switch is constant power not the switched leg-- was that a typo?

Sounds like the feed to the unit is wired thru the other switch somehow.

Bill , did you check to see if you had 120V not a test light, with a load on the unit? Did you replace the module in the fan as well as the wall switch- skype me if you want to talk about it-
 

gar

Senior Member
140427-0827 EDT

Little Bill:

I do not understand this system. I looked at an Internet Lutron page and it was next to useless in providing a useful description of how the system works.

I suspect there is some sort of carrier current communication.

From your description you seem to have a wall control that can provide two independent functions. One function is on-off and dimming control of a remote light. The second function is on-off control and speed adjustment of a fan motor. Because only a single receiver module is use it is necessary that both the light and fan be in the same location.

You mention a hot and neutral supply to the wall control location, and three wires from the wall control to the receiver module at the light-fan assembly. I suspect that the three wires are neutral and hot with the third wire being a data line. Likely the data signal is transmitted using the data line and neutral pair.

That a lower impedance shunted across the input (hot-neutral) to the wall control allows the system to work implies that Lutron did not provide a sufficiently low high frequency impedance between the input hot and neutral to make their communication (data) path work reliably. Quite possibly a 0.1 to 1.0 mfd 600 V ceramic capacitor from hot to neutral at the input side of the wall control might solve the problem.

Lutron needs to provide a better theoretical description of their system so that one can understand its operation. Simple one-line diagrams with neblus descriptions are of no value. If you do not have an understanding of the basics of a system, then it is hard to troubleshoot such a system.

.
 

Dennis Alwon

Moderator
Staff member
Location
Chapel Hill, NC
Occupation
Electrical Contractor
I think I mis read Bills scenario-- there is only 2 wires from the switch to the module then 5 wires in the module-- 2 of them is power from the switch and the other 3 are neutral, fan, light.
 

Dennis Alwon

Moderator
Staff member
Location
Chapel Hill, NC
Occupation
Electrical Contractor
Bill if the bulb is LED then what is the wattage. The unit says it must have 40 watt minimum.....Not sure that is your problem but it may be worth investigating and eliminating that issue.
 

Little Bill

Moderator
Staff member
Location
Tennessee NEC:2017
Occupation
Electrician
Bill I am confused here

It is a dimmer and fan control in one unit. It has a wall unit that replaces a wall switch. It also has a module that goes in the fan canopy. You don't need a neutral in the wall box. You just either wire it as a SP or 3-way, SP in my case. The module has four wires. One is black for power from the switched leg. The other wires are: red for the light, yellow for the fan, and white for neutral. It also has a remote to operate it. The wall unit has a top section (dimmer) and a bottom (fan) section. There are LED lights at each section to indicate the level you have it set at.


The black bold--If the switch has a neutral then it must be in the switch box.... No.

I meant the wall control (switch in the wall box) does not need a neutral. The canopy module needs the neutral which is fed from the wall box where the power comes in.

The red bold-- black on the switch is constant power not the switched leg-- was that a typo?

No, the wall control sends constant power even though it's wired as a switch. The wall control sends a signal, in addition to the power, to the canopy module

Sounds like the feed to the unit is wired thru the other switch somehow.

No it's not wired through the other switch. Only thing in common is the power to the 3-gang box is spliced/pigtailed to provide power to all the switches in the 3-gang box.
I completely removed the 3-way switch and tried the wall control. It would not work without putting the test light parallel with it to create a load.


Bill , did you check to see if you had 120V not a test light, with a load on the unit? Did you replace the module in the fan as well as the wall switch- skype me if you want to talk about it-
I put the test light in the ceiling and checked the voltage there and in the wall box, both had 120V.
 

mopowr steve

Senior Member
Location
NW Ohio
I just had a conversation with Leviton the other day about some home automation and he said that they ( I know it's not lutron but) are having issue with wall controls that utilize communication on the power wires between units when LED bulbs are being used. I guess Leviton is going to a new system.
So try putting regular bulbs in the sockets and let know what happens!
 

Little Bill

Moderator
Staff member
Location
Tennessee NEC:2017
Occupation
Electrician
140427-0827 EDT

Little Bill:

I do not understand this system. I looked at an Internet Lutron page and it was next to useless in providing a useful description of how the system works.

I suspect there is some sort of carrier current communication.

From your description you seem to have a wall control that can provide two independent functions. One function is on-off and dimming control of a remote light. The second function is on-off control and speed adjustment of a fan motor. Because only a single receiver module is use it is necessary that both the light and fan be in the same location.

You mention a hot and neutral supply to the wall control location, and three wires from the wall control to the receiver module at the light-fan assembly. I suspect that the three wires are neutral and hot with the third wire being a data line. Likely the data signal is transmitted using the data line and neutral pair.

That a lower impedance shunted across the input (hot-neutral) to the wall control allows the system to work implies that Lutron did not provide a sufficiently low high frequency impedance between the input hot and neutral to make their communication (data) path work reliably. Quite possibly a 0.1 to 1.0 mfd 600 V ceramic capacitor from hot to neutral at the input side of the wall control might solve the problem.

Lutron needs to provide a better theoretical description of their system so that one can understand its operation. Simple one-line diagrams with neblus descriptions are of no value. If you do not have an understanding of the basics of a system, then it is hard to troubleshoot such a system.

.

Gar,
Here is a link to a PDF with the manual. Maybe it will help you see how this unit works.

It does not have a data line. It just needs the switched leg (which is not switched at all) from the wall control to the module. The module needs hot & neutral, then it has two wires, red for light & yellow for fan. So the module has four leads on it.

http://www.smarthome.com/manuals/6615wh.pdf
 

Little Bill

Moderator
Staff member
Location
Tennessee NEC:2017
Occupation
Electrician
I just had a conversation with Leviton the other day about some home automation and he said that they ( I know it's not lutron but) are having issue with wall controls that utilize communication on the power wires between units when LED bulbs are being used. I guess Leviton is going to a new system.
So try putting regular bulbs in the sockets and let know what happens!
The bulbs are not LED or CFL. They are candelabra style incandescent bulbs.

Plus I ruled that out when I disconnected the fan light and put the test light on. I got the same results with my test light.
 

PetrosA

Senior Member
Ok, so if I'm understanding things correctly:

When you hook up an incandescent light to the circuit ahead of the controller, or between the controller and the module in the fan everything works fine. If you hook up the incandescent light (in place of the fan's lights) to the load side of the module in the fan, it does not work correctly.

If that's right, then I would look for sources of noise that may have been installed recently. LEDs, CFLs, fluorescent lights somewhere in the vicinity (maybe new basement lights?) or some other kind of electronics that may be messing with the power quality on that circuit or broadcasting some EMF in the vicinity of the controller/module.
 

gar

Senior Member
140427-1109 EDT

Little Bill:

Step 12a has a limited schematic but no real useful information. Thus, no real way to know how the Wall Control works.

The Wall Control appears as a terminal device with a ground connection. We don't known how essential the ground connection is to the operation of the Wall Control.

Is the ground only to serve as a safety ground for the wall plate, or is it a critical part of the communication path?

How does the electronic circuit in the Wall Control obtain energy to power it? Is the ground connection part of the energy source, or is all energy derived from the series hot line thru the Wall Control? The minimum 40 W incandescent lamp load may or may not be important relative to the operation of the Wall Control.

It is probable that the dimmer function within the Canopy Module requires the 40 W minimum load to function.

It may be necessary to try to determine whether the Canopy or Wall Control is where the problem exists. It is fairly clear that some sort of carrier current method is being used for signalling from the Wall Control to the Canopy module. Knowing the carrier frequency and signalling code would be useful. Then this could be monitored and probably determine where to look for the problem.

.
 

Dennis Alwon

Moderator
Staff member
Location
Chapel Hill, NC
Occupation
Electrical Contractor
Ok, so if I'm understanding things correctly:

When you hook up an incandescent light to the circuit ahead of the controller, or between the controller and the module in the fan everything works fine. If you hook up the incandescent light (in place of the fan's lights) to the load side of the module in the fan, it does not work correctly.
After talking to bill on skype I would say this is not correct. He hooked the 120V pigtail of a 100 watt bulb ahead of the light to the fan- he disconnected the red to the light on the fan and wired it to the red on the controller. Same issue. We discussed eliminating the entire circuit by using an ext. cord from another cir and a piece of 14/2 thru the air to the fan and see what happens. We also talked about eliminating the module and use a sep. fan control and light dimmer.

I am thinking there may be an issue in the fan that is causing problems but I can't fathom how that is possible unless this fan has it's own built in module-- not the case if there are 3 wire coming out the top.
 

PetrosA

Senior Member
After talking to bill on skype I would say this is not correct. He hooked the 120V pigtail of a 100 watt bulb ahead of the light to the fan- he disconnected the red to the light on the fan and wired it to the red on the controller. Same issue. We discussed eliminating the entire circuit by using an ext. cord from another cir and a piece of 14/2 thru the air to the fan and see what happens. We also talked about eliminating the module and use a sep. fan control and light dimmer.

I am thinking there may be an issue in the fan that is causing problems but I can't fathom how that is possible unless this fan has it's own built in module-- not the case if there are 3 wire coming out the top.
I guess I'm confused. I thought he meant that if he hooks up a 100W bulb at the switch as an additional load, either to the line or load side terminal, the dimmer works correctly and that putting the same light bulb on the load side of the fan control module doesn't fix anything. If that were the case, I'd suspect that some interference is messing with the signal between the controller and module in the fan that a light bulb is smoothing out. It would still be possible that something in the fan is the source of that interference - possibly some PCB for load control or fan control.
 
Top