Lights-from-bottles project: is it feasible?

[Deeg]

Hello all, I'm looking into a making some ceiling pendant lights from different colored bottles. I want to hang three bottles (red, green, and blue) from the ceiling with a cable. The lights inside the bottles will be 12V LED lights; I want something bright, maybe ~10w like this one. The lights will be suspended inside the bottle using a socket like this one (I know the LED I linked is double-contact and the socket is single-contact; these are examples). I'm using 12v LEDs because they will fit inside the bottles through the neck (I don't want to cut the bottles).

For aesthetics I want to minimize the number of power wires hanging from the ceiling so I was planning on using the main cable that hangs the bottles as the ground wire with another wire being the positive feed. This means that the LEDs will be wired in parallel. I assume that it is safe to have an exposed 12v ground wire: the danger is a short between the two wires.

Assuming I can figure out how to safely hang the bottles from the ceiling and suspend the LEDs inside the bottles, what else should I be concerned about? These are the areas I can think of:

1) Heat from the LEDs. There will be little in the way of heat-sinking and they will be enclosed in the bottle. Is 10w too much for this set up? If it does get too hot, what are the dangers? Just burning out the LED?

2) Power supply. For the setup described above I need at least a 30w PS, preferably more like 40w. Since the PS will likely be installed in the ceiling with the junction box (right?) I assume I need one that is rated for such a purpose. What should I look for?

3) Would colored LEDs work better? I want the lights to be red, green, and blue. I'm planning on using white LEDs and letting the colored bottles filter the light. Would it be more efficient if I used red, green, and/or blue LEDs? I haven't been able to find colored LEDs that are as bright.

Thanks!

 

[jpanhalt]

Sounds interesting. Do you have an atic above the ceiling? I assume you do.
@1: Don't know the answer to that, but there are so many variables, I would just experiment (after looking at the most similar examples I could find)
@2: Requirements for an attic are different, I believe, than for a plenum. Since you have an attic, it will probably be easier. Can you talk casually with your inspector?
@3: This is purely a matter of opinion. I would go with colored bottles and clear LED's to get sparkle. I have gone with halogen bulbs and halophane-type shades (aka ribbed glass) for the same reason.

John

 

[audioguru]

The light bulb is much more efficient if you use red, green and blue LEDs instead of blocking most of the white light you do not want with filters.
A "white" LED is actually a blue LED plus a yellowish phosphor so red and a few other colors will be dim.

I notice that the light bulbs are No Name Brand so the quality could be variable.

 

[jpanhalt]

AG is absolutely right. If you want efficiency, just use bare red-orange LED's. Blue LED's are only about 38% as efficient as red-orange ones. Personally, I would find that disgusting in my home.

I was thinking, however, if heat conduction through the air between the LED's and glass is a problem, you might fill the space with a dielectric of much higher refractive index, such as ethylene glycol. That might also give an interesting sparkle to the lights. (Experimentation required)

John

 

[audioguru]

The light bulbs have 99 hot LEDs tightly crammed together with hardly any heatsink and no free air for convection cooling. Therefore they have no guarantee for their lifetime.
Maybe they will begin to dim permanently from over-heating in a week, a month, a year?

 

[4pyros]

For heat dissipation I would fill the bottle with clear oil and put the LED in that.

 

[tcmtech]

Sounds perfectly feasible to me if you are using a liquid cooling system!

If it was me I would set up a few and let them run continuously for a while to see how they work out. In the end an actual run as used test is the only way you will find out if they will work long term or not.

 

[dr pepper]

Search the forum, someone did something like this recently with cups & saucers, or was it you?
Leds would be a safer way as less heat is produced, you can get MR16 12v led lamps in various colours inc white.

 

[Deeg]

Thanks for the replies!

@2: Requirements for an attic are different, I believe, than for a plenum. Since you have an attic, it will probably be easier. Can you talk casually with your inspector?

I don't have an attic; I'm in a condo and I don't have access from the floor above. Is this a show-stopper in your mind?

The light bulb is much more efficient if you use red, green and blue LEDs instead of blocking most of the white light you do not want with filters.
A "white" LED is actually a blue LED plus a yellowish phosphor so red and a few other colors will be dim.

I notice that the light bulbs are No Name Brand so the quality could be variable.

Yeah, I figured as much. The problem is that I can't find any green or blue LEDs with bayonet sockets that are bright enough. I'm using the cheap LEDs for now until I determine that it'll work. Do you have suggestions on where to get quality LEDs? I was considering SuperBrightLEDs.com.

I was thinking, however, if heat conduction through the air between the LED's and glass is a problem, you might fill the space with a dielectric of much higher refractive index, such as ethylene glycol. That might also give an interesting sparkle to the lights. (Experimentation required)

I hadn't thought of that; that's a very interesting idea! Would Propylene glycol work as well? Ethylene glycol is moderately toxic and I'd like to avoid it if I can.

What about power supplies? I have a 12v/5A transformer laying around; can I use that? It has plenty of power but I'm concerned about fire hazard.

Leds would be a safer way as less heat is produced, you can get MR16 12v led lamps in various colours inc white.

Yeah, that was me. I'm slowly replacing all the ugly lights in my condo.

 

[KeepItSimpleStupid]

How about "lamp chain" which is used for hanging lamps.

 

[tcmtech]

I hadn't thought of that; that's a very interesting idea! Would Propylene glycol work as well? Ethylene glycol is moderately toxic and I'd like to avoid it if I can.

I think you have your facts messed up. Ethylene glycol is at best mildly toxic and even then its only if you drink a fair amount of it.

To be honest any drain, toilet or stove cleaners you have at home are far more toxic to you than ethylene glycol would be.

 

[jpanhalt]

@1 I don't know the fire rules for condos. I suspect they may be pretty stringent as what you describe sounds like a multifamily unit (e.g., apartment). Also, there may be condo regulations on top of fire code. I would be concerned about a buried power supply anywhere, not just for fire, but also for troubleshooting and repair.
@2 Any non-electrically conductive, non-corrosive, relatively non-flammable, and relatively high boiling fluid should work, e.g., propylene glycol, oil, etc. Both glycols are relatively non-flammable too and have high refractive indexes due to the polar hydroxyl groups. Silicone oil might be another choice. I would try to stay away from liquids that support microbial growth well, such as edible oils.

John

#1 I was typing while tcmtech posted. The major concern with ethylene glycol is that it is sweet. Thus, pets that get into it are likely to eat a toxic amount. Propylene glycol, while also sweet, is less toxic.
#2 BTW, I am not suggesting that you re-invent the "lava Lamp." Any similarity is merely coincidental: https://science.howstuffworks.com/innovation/science-questions/question36.htm

 

[shortbus=]

One thing about LEDs that no one has addressed yet is the illuminating angle of the light. Unlike a incandescent bulbs LEDs emit light in a limited angle. Unless they have changed over the years.

 

[jpanhalt]

That's why I suggested something with a high RI (https://spie.org/x94809.xml). I know very little abut LED's, but I was aware of their narrow angle of emission. Old time PBB transformer oil would be great I was trying to be more green.

John

 

[audioguru]

One thing about LEDs that no one has addressed yet is the illuminating angle of the light. Unlike a incandescent bulbs LEDs emit light in a limited angle. Unless they have changed over the years.

Didn't you see the link to the light bulb that has 99 LEDs all over it?

 

[Deeg]

#1 I was typing while tcmtech posted. The major concern with ethylene glycol is that it is sweet. Thus, pets that get into it are likely to eat a toxic amount. Propylene glycol, while also sweet, is less toxic.

jpanhalt said it; I'd use ethylene glycol if that was the only option but it sounds like PG will work just as well so it makes sense to go with it.

 

[jpanhalt]

Hey, I use both and don't even have any dogs. For my sprayers and so forth, I use PG. For my engines, I use EG. No explanation is needed.

John

 

[MrAl]

Hi,

In a pinch distilled water will also work if you can find a way to deal with the evaporation.

10 watts is enough power such that it has to be dissipated properly with heat sinking or relying on convection currents through the liquid to the sides of the container and given enough surface area it should dissipate well enough, but a test of one unit first is always in order.

Alternately a pumped liquid cooling system with the heatsink hidden somewhere.

A 5 amp power transformer isnt too bad of an idea, but keep in mind that many house fires in the past were caused by simple door bell transformers that went bad and heated up much too much. A fuse can help here, but not only a fuse but also one or more thermal switches that turn off when the temperature exceeds the limit of the rating of the switch. These make things much safer to run long term and are used in coffee makers, house fans, and lots of other stuff like surge protectors. The thermal switches should be mounted so that they are in very close contact with the windings. In house fans they mount them right in the winding or between the winding and the metal core of the motor.
Of course you have to rectify the AC from the transformer at the very least to run the LED's.

 

[KeepItSimpleStupid]

This will probably fall under Class II wiring: https://ecmweb.com/content/understanding-nec-circuit-classifications

< 24 V (AC or DC) and under 100 W. The power source has to be either fused or use a PTC (Positive Temperature Coeficient) thermister. There are transformers, typically around 40 VA that can be purchased as "energy limiting". These do not require fuses and the secondary can survive a direct short forever.

Remember that in any raceway, the voltage rating of the wiring has to be rated for the highest voltage.