Dummy Load for Incandescent Dimmer Used for LED Lights

[jocanon]

I have a dimmer switch, the Lutron Spacer System, that is made for incandescent or halogen light bulbs but not LED. I want to use the switch on LED recessed lights (it is the only dimmer switch I found in my price range that can be controlled via IR for multiple switches in the same room). I have done some research, as well as my own experimentation, and discovered that if I include a 25 watt incandescent bulb in the circuit, the LEDs work just fine with the dimmer. Without the 25 watt incandescent bulb, the LEDs will not turn off or dim. I may be able to get away with less than 25 watts, I have yet to test that. 25 watts is the smallest light bulb I have laying around to test with at the present.

Now, what I am wanting to do is put a resistor in the circuit to act as a dummy load instead of the incandescent so I will not have to hide a 25 watt incandescent anywhere or worry about needing to replace it when the bulb burns out. I have seen this done in other forums.

I have several questions regarding this resistor as a dummy load solution:

1. Is it safe? I can mount it to the recessed light can as a heat sink. The can has a built in thermal shutoff feature already connected. Or would it be safer to mount the resistor remotely with its own heat sink and thermal shut off circuit.

2. Other forums I have seen them use this type of chassis mount resistor for this:
**broken link removed**
Would this be a good resistor for this project and could I use thermal paste to mount it to the recessed light can? I would insulate the leads with heat shrink.

3. Would the way to hook up the resistor simply be: connect it to the hot and neutral wires (black and white wires) in parallel with the LED recessed lighting?

4. Would I potentially be in violation of any sections of the National Electric Code (NEC)? If yes, is there a way to build this and install it that would be in keeping within the NEC requirements? In other words, what key things would I need to be sure I do in order to be in compliance with NEC, particularly with regard to fire safety?

5. Lastly, is it safe? I know I already asked this, but I want to add emphasis. I do not want to burn my house down. Probably a better way to word this question is, is there a way it can be done safely? Obviously it can be done in an unsafe manner that would burn the house down, but I am wondering if there is a way this can be done safely, and to code. Further, if I mount it to the recessed light can that is IC rated (meaning it can come in direct contact with insulation) would I be correct in assuming that the IC rating is probably null and void and I would need to be sure no insulation touches the can is it might get too hot (still falls under the "is it safe question") or can it still come into contact with insulation because the thermal shut off component of the can is what regulates how hot it can get, and the manufacturers and powers that be knew this upper limit when they gave it the IC rating, which would mean that it still maintains its IC rating and can still safely come in direct contact with insulation?

I think some of these questions are going to be difficult, if not impossible, to answer definitively (i.e. will the can loose its IC rating, may not be able to know for certain...), so I am interested in opinions and thoughts on the matter, even if you do not know for sure or cannot cite the code sections, etc...

Thanks,
Jeremy

 

[KeepItSimpleStupid]

Did you investigate "Dimmable LEDS".

Once you modify, you loose the UL rating.

Your not likely to need 25 Watts. Those resistors will be fine. Guessing 5-10 W. Have a nite light bulb? You can test with soldered wires.

I really don't know what you have to work with, BUT wiring all the loads to another enclosure COUD work. So might using the housings.

The wire you use will be important. Building wire, appliance wire and Teflon insulated wire. No lower than 18 AWG. Preferably the size of the circuit (12, 14 AWG).

 

[MrAl]

Hi,

I had recommended using a bulb in conjunction with an LED non dimmable bulb to a friend a long while back. He picked up one of those "Y" sockets where you screw that into the ceiling lamp socket and you get two sockets, then you can screw the LED bulb into one socket and the incandescent bulb into the other and that gives you some dimming features for both bulbs. He used that setup for about a year before i got him a regular dimmable LED bulb, and now he uses that exclusively without the other bulb.

The problem with a resistor substitute is that the resistor dissipates power and whenever you have power dissipation you have heat, and whenever you have heat you MUST provide a free air flow to the source of the heat (resistor) or else the temperature builds up to an extremely high level. To give you some idea how this works in physics, in theory a perfectly insulated power of 1 millionth of a watt (1/1000000 watt or 0.000001 watt) placed inside a regular 8 foot high room as large as a football field will eventually build the temperature up to infinity. But of course before that happens something burns down and the heat escapes. However, given two small vents one on one end and another on the other end, there is now free air flow getting to the heat source, so it dissipates from the heat source into the box and then out to the free air space. The temperature stays at a safe level.

Even 10 watts is enough to cause problems, and that requires quite a bit of free air space also. The way this is handled normally is to use a very much over rated resistor than the problem really requires, and for something that is somewhat enclosed a 10 to 1 ratio would not be ridiculous but safe. So a 100 watt resistor operating at 10 watts, but again with free air flow. If there is no free air flow then all is lost.

So the problem is an enclosed heat source, and the solution is free air flow or forced air flow. Note that a heatsink does NOT solve the problem unless the heatsink itself has free air flow, and that is because again the solution is free air flow and this is even when a heatsink is also required.

What a heatsink does is draws the heat into a larger volume and that volume being larger must therefore have a larger surface area, and that larger surface area means the heat can dissipate into the free air much faster and thus help to cool the main heat source (the resistor). Heatsinks are designed to have a large surface area to volume ratio so they can help dissipate the power faster, but again into the free air.

So if you plan to use a resistor you must use extreme caution to make sure that the heat can be dissipated into the free air no matter how it is done.

This is sometimes hard to do when the heat source has to be enclosed. In a regular chassis, air holes are often incorporated in order to allow free air flow, or else the heatsink is connected such that it is on the outside of the box, and thus the heat again gets out of the box into the free air.

Another requirement for a safe setup is to use a non resettable thermal fuse. These are available with different temperature ratings. The idea here is that if something blocks the free air flow, the thermal fuse blows open and disconnects the power. The worst case there is that the light goes out, rather than burn down the house. The thermal fuse however must be mounted to the device (resistor) correctly, in a manner that allows it to attain the same or nearly the same temperature as the resistor. That way it truly detects the temperature of the resistor.

Just so you know, some bulbs are designed such that even they can not be used in an enclosed ceiling box and they state that on the packaging usually.

Is this legal? Probably not. Almost nothing out of the ordinary is legal. So you better be careful if you decide to do this.
Also keep in mind that engineering mainstream consumer devices means rigorous testing to make sure there is no danger. This often requires testing and retesting over a period of time to make sure a new design is capable, and this is often done by engineers with advanced degrees and years of experience, and they still dont get it right sometimes.

So after reading the above if you think you are up to this task, then by all means proceed and i wish you good luck. However, with my 40+ years of experience with design and testing in the lab and in the field and seeing how the craziest things can go wrong with intial designs, my best recommendation is to avoid all the work and possible heartache and just buy a dimmable LED bulb. Even then you may want to test it over several hours to make sure it doesnt get too hot also.

 

[jocanon]

Did you investigate "Dimmable LEDS".

Once you modify, you loose the UL rating.

Your not likely to need 25 Watts. Those resistors will be fine. Guessing 5-10 W. Have a nite light bulb? You can test with soldered wires.

I really don't know what you have to work with, BUT wiring all the loads to another enclosure COUD work. So might using the housings.

The wire you use will be important. Building wire, appliance wire and Teflon insulated wire. No lower than 18 AWG. Preferably the size of the circuit (12, 14 AWG).

Thanks for your response. The LEDs are dimmable, it is the particular switch that needs help in dimming them (it is not a switch designed to be used with LEDs, dimmable or not). As far as wires, I was just thinking I would solder the hot and neutral from the household circuit directly onto the leads to the resistor, so I would be using Romex 14 AWG wire. Could ceramic resistors work as well, or would you recommend sticking with the surface mount resistors?

 

[jocanon]

Hi,
So after reading the above if you think you are up to this task, then by all means proceed and i wish you good luck. However, with my 40+ years of experience with design and testing in the lab and in the field and seeing how the craziest things can go wrong with intial designs, my best recommendation is to avoid all the work and possible heartache and just buy a dimmable LED bulb. Even then you may want to test it over several hours to make sure it doesnt get too hot also.

As I already mentioned above, I do have dimmable bulbs (I posted that at the same time you posted your response, so you didn't see it). My problem is I want to use a dimmer that is not designed for LED dimmable bulbs. At any rate, I appreciate your response. I think you make good points. Now I am leaning to simply putting an incandescent light fixture in my attic above the recessed lighting. I think that is a much easier and less problematic solution even though I will periodically have to change out the bulb. One concern I have is, aren't they making incandescent bulbs illegal so they will no longer be selling them? What can I do then if I cannot even get an incandescent bulb in the near future. Maybe I will just not be able to use the Lutron Spacer System anymore. It says I can use halogen lights too, are those going away as well?

 

[MrAl]

Hi,

The trend is to use the curly bulbs, but i am not sure if you can get dimmable ones or not as i never needed that.

Dimmers should work on dimmable LED bulbs, but they probably dont work on non dimmable LED bulbs. Who said you need a special dimmer? Maybe some dont work, but i think the newer models should work.

 

[KeepItSimpleStupid]

I was thinking, something like this: http://www.homedepot.com/p/Wiegmann...r-Pull-Box-with-Knockout-SC101004RC/100118037

You could mount a 1/8" aluminum plate to the bottom like most process enclosures have. e.g. **broken link removed**

Not too crazy over the solder direct. There are other neater, more expensive methods. DIN rail. e.g. http://www.automationdirect.com/adc...nal_Blocks/DINnector_DIN-Rail_Terminal_Blocks Just using this as an example. You have to buy bpxes from these guys.

You assemble terminals/jumpers on a shallow T-shaped rail. They could be arranged like
stop-ground-neutral-hot-end-cap-(Repaeat*x <round-neutral-hot-end-cap->)stop

The terminals are typically open at one end, so the entire set has to be closed. You can use the end caos as partitions. The ground terminals are red/yellow and don;t need caps.

You resistors would be connected to a terminal vis stranded wire. The romex wires would enter, be strained relieved and connected directly to a set, the neutral-ground-hot might be better suited, but it requires more end caps.
It's more expensive, neat and clean.

 

[jocanon]

Hi,

The trend is to use the curly bulbs, but i am not sure if you can get dimmable ones or not as i never needed that.

Dimmers should work on dimmable LED bulbs, but they probably dont work on non dimmable LED bulbs. Who said you need a special dimmer? Maybe some dont work, but i think the newer models should work.

I don't know who said it, but I am telling you it is true...you cannot use certain dimmers even on dimmable LEDs. I know because I can go into my family room and demonstrate it right now. I have dimmable LEDs, just recently purchased from Lowes. They say dimmable on the box. They work perfectly with the dimmers I got that say they are compatible withe LEDs, but not with the Lutron Spacer System dimmers because they say right on the box only works with incandescent or halogen. But you can make it work with dimmable LEDs if you put an incandescent on it. I know I can get dimmers that are compatible with LEDs without an incandescent (I have 3 installed in different rooms right now and two more in a box waiting to be put in my kids rooms). I would gladly do get an LED compatible dimmer if you could show me one that can be controlled via infrared so I can use my Harmony remote, and cost less that $50 a switch. That is what I get with the Spacer System (on Amazon/ebay). I cannot find it in LED compatible dimmers. There is an LED dimmer Lutron makes that can be controlled via RF but that doesn't work, I need IR, as far as I can tell even in the less than $100 category, IR controlled dimmable LED compatible dimmers do not currentlt exist on the market.

I am surprised you guys do not know this. It is a very well known fact. If you check the package on any dimmer at the big box stores it will always say what type of bulb it works with and what type it does not. I do not fully understand why some dimmers do not work with dimmable LEDs, but I think it has something to do with the low voltage needed to turn them on and particularly with the Spacer System, it needs to draw a small current to function even when lights are off, I think this small current us just enough to not let the LEDs turn off...trust me, that is exactly what happens. If I do not have an incandescent with the Spacer System dimmer, the LEDs will turn on but never turn completely off.

 

[jocanon]

I was thinking, something like this: http://www.homedepot.com/p/Wiegmann...r-Pull-Box-with-Knockout-SC101004RC/100118037

You could mount a 1/8" aluminum plate to the bottom like most process enclosures have. e.g. **broken link removed**

Not too crazy over the solder direct. There are other neater, more expensive methods. DIN rail. e.g. http://www.automationdirect.com/adc...nal_Blocks/DINnector_DIN-Rail_Terminal_Blocks Just using this as an example. You have to buy bpxes from these guys.

You assemble terminals/jumpers on a shallow T-shaped rail. They could be arranged like
stop-ground-neutral-hot-end-cap-(Repaeat*x <round-neutral-hot-end-cap->)stop

The terminals are typically open at one end, so the entire set has to be closed. You can use the end caos as partitions. The ground terminals are red/yellow and don;t need caps.

You resistors would be connected to a terminal vis stranded wire. The romex wires would enter, be strained relieved and connected directly to a set, the neutral-ground-hot might be better suited, but it requires more end caps.
It's more expensive, neat and clean.

Those sound like good ideas. Maybe I can do it after all...I just don't know if it is worth it, or just get an incandescent in the attic so the LEDs will work right.

 

[MrAl]

I don't know who said it, but I am telling you it is true...you cannot use certain dimmers even on dimmable LEDs. I know because I can go into my family room and demonstrate it right now. I have dimmable LEDs, just recently purchased from Lowes. They say dimmable on the box. They work perfectly with the dimmers I got that say they are compatible withe LEDs, but not with the Lutron Spacer System dimmers because they say right on the box only works with incandescent or halogen. But you can make it work with dimmable LEDs if you put an incandescent on it. I know I can get dimmers that are compatible with LEDs without an incandescent (I have 3 installed in different rooms right now and two more in a box waiting to be put in my kids rooms). I would gladly do get an LED compatible dimmer if you could show me one that can be controlled via infrared so I can use my Harmony remote, and cost less that $50 a switch. That is what I get with the Spacer System (on Amazon/ebay). I cannot find it in LED compatible dimmers. There is an LED dimmer Lutron makes that can be controlled via RF but that doesn't work, I need IR, as far as I can tell even in the less than $100 category, IR controlled dimmable LED compatible dimmers do not currentlt exist on the market.

I am surprised you guys do not know this. It is a very well known fact. If you check the package on any dimmer at the big box stores it will always say what type of bulb it works with and what type it does not. I do not fully understand why some dimmers do not work with dimmable LEDs, but I think it has something to do with the low voltage needed to turn them on and particularly with the Spacer System, it needs to draw a small current to function even when lights are off, I think this small current us just enough to not let the LEDs turn off...trust me, that is exactly what happens. If I do not have an incandescent with the Spacer System dimmer, the LEDs will turn on but never turn completely off.

Hi,

We dont have to buy dimmers every day.
Sometimes technology is not that unique in that everything is not so much the same that you can not always say the same thing about all products even if similar. I've been surprised at what i see out there these days.
Another example is one of the Panasonic microwave ovens. It's got a built in inverter, so you would think that it would work on ALL power settings, but it doesnt. You would also think that the power setting is just like other mic ovens, BUT it's NOT, you have to press the friggin' power button 10 friggin' times to get to power level 1. Who designed such a stupid thing.
And that is only ONE example.

So it does not surprise me too much to find that some dont work, but since LED makers must know the workings of a standard dimmer they must go by that.

Anyway, a friend has an LED bulb in the ceiling and he uses an RF type remote. That means some RF remote dimmers do work with LED bulbs.
If you are having this much trouble go out and buy one that works.

 

[jocanon]

If you are having this much trouble go out and buy one that works.

Again, I need IR not RF. I do not have a universal RF remote, not even sure there is one, but I do have a universal IR remote (Harmony). So I need a dimmer controlled via IR, not RF.

 

[crutschow]

I would get some small night-light type incandescent bulbs as small as you can find (I've seen as small as 3W) and experiment to see how small a bulb you actually need.
If you want to use a bulb as a load, you can greatly increase their lifetime by connecting two bulbs of the same wattage in series, This would significantly minimize how often they would have to be replaced.

 

[jocanon]

If you want to use a bulb as a load, you can greatly increase their lifetime by connecting two bulbs of the same wattage in series, This would significantly minimize how often they would have to be replaced.

Good to know. Thanks.

 

[jocanon]

The problem with a resistor substitute is that the resistor dissipates power and whenever you have power dissipation you have heat, and whenever you have heat you MUST provide a free air flow to the source of the heat (resistor) or else the temperature builds up to an extremely high level.

It will be in the attic which has some air flow through the vents, not a lot, but some...would this be enough, or do you mean it has to have fan.

 

[KeepItSimpleStupid]

An interesting blurb: https://www.archlighting.com/technology/leds-a-deep-dive-in-dimming_o

so, you have a couple of things going on:
The dimming characteristics are different.
Th incandescent lamp, needs a minimum light output to always come back and start at the same place.

So, I'm thinking that a 7W nite light bulb might be better than a 7W resistor.

 

[MrAl]

Again, I need IR not RF. I do not have a universal RF remote, not even sure there is one, but I do have a universal IR remote (Harmony). So I need a dimmer controlled via IR, not RF.

Oh i see, well that sounds strange that they dont make one, but that's the way things are these days.
Some people build their own stuff but yeah that is harder to do.
The remote the friend has is a separate remote, but it is small so it is not too much more trouble having that extra RF remote.

It will be in the attic which has some air flow through the vents, not a lot, but some...would this be enough, or do you mean it has to have fan.

Most attics are large enough, as long as you have a good heat sink or at least have the resistor out in the free air of the attic. Free air means it is mounted so that the air in the space around it can circulate with convention currents. Forced air means a fan.

Some cautions would be:
Use a very much over rated resistor, like 10 percent would be very good.
Make sure nothing can drop onto the device and thus block the air flow, especially paper, cardboard, etc.
Make sure no debris can build up on it over time, which includes dust.
Probably should mount it inside a steel box with air holes like a regular chassis would have.
Try to think of anything that can go wrong and correct it.
Last but not least:
Have a mechanical motor driven arm mounted such that if it gets too hot, it throws your home owners insurance policy in the garbage <chuckle>
Seriously though, if a fire did start and they found out it was that it might be a problem with the insurance company.

 

[jocanon]

Seriously though, if a fire did start and they found out it was that it might be a problem with the insurance company.

That's the part that makes me nervous...I think it would keep me up at night and probably make the effort not worth the trouble. I may try the nightlight idea. What I am thinking is mounting 3 separate lights in the attic (I have 3 separate LED circuits with Spacer System dimmers this applies to). I am thinking the cheapo pull string lights from Lowes (like less than a couple bucks a pop) that have a three prong outlet included on them. Then I will put a night light on each one of those power outlets if that works to fix the LED dimming and leave the light bulb pull string turned off (not the nightlight light bulb, but the larger one attached to each fixture) unless I want light in the attic, then I always have the option of turning one or all three on while I am up there. That way I do not think anything will be in code violation (assuming I connect everything correctly according to NEC codes...) or give the insurance company an out in event of fire. If I ever sell the house, the new owner will probably wonder why I have three lights with nightlights in the attic lol...unless I explain it to them. I will just tell them we make our kids sleep up there when they are bad, but we are nice enough to give them lights. The space is only about 3 feet high at its high point, so that would be cruel and unusual punishment! Actually, the more I think about it...my kids would love that, they are always begging me to get in the attic when I am up there lol, btw, in case you can't tell, I am kidding about making them sleep up there...I don't need cps knocking on my door in case they are reading this and don't get the humor .

 

[KeepItSimpleStupid]

A duplex outlet gets you two nightlights. A dual box gets you 4. 4*7 = 28W.

I put a quartz halogen light in the attic. It says to only use outside, so it's kinda a gray area.

The light's never on for very long AND there is an indicator if it should accidentally get switched on. It's on a dual box, where the hall height is up/down and the attic light goes left/right with an indicator. I'd love to put another one up there.