[bvbellomo]

I built a custom LED fixture for my fish tank, and got to thinking about whether I could use the same lighting in my house - it is much cheaper (long term) than AC LED bulbs or compact florescents, or probably any other lighting. I could easily put a driver inside a wall or ceiling, and run low voltage wiring between individual LEDs. The driver could work on a standard light switch, or use a potentiometer as a dimmer.

The only problem is when I go to sell the house, or if I had it inspected for some other reason. Is there a way to do this to code? Can it be exempted if it is below a certain voltage? Obviously, a buyer might not want LED lighting, so that would still be an issue selling the house.

If there was an easy legal way to do this, or if people knew they were staying in 1 place for many years, I would think this would be much more common.

 

[joed]

All of the 120 volt portions needs to be in accessible junction boxes with covers.

 

[bvbellomo]

120 volt portions are not relevant. With few exceptions, MeanWell drivers top out at 54 volts. For lighting a house (and not a shopping mall) 54 volts is plenty.

Of course, common drivers require 120 volt input, so would the driver need to be entirely within a junction box? Or would only the connection to the driver need to be within a junction box? Either way, this is a much smaller problem then the wiring for the lights themselves.

 

[Ocelaris]

I'm going to have to chime in here and say that LEDs are not cheaper than any other lighting. Lumens per watt, LEDs are in the 60-70 lumens/watt range, where as Compact Fluorescents are 80-90, and HIDs are 100-250. If you're talking about sufficiently lighting your home with DC powered LEDs, you're going to need to consider the problem of DC voltage drop over a long distance. You're going to need significant balancing of current with voltage regulators and large diameter copper to not induce voltage drop along the distance of the run.

It's funny to me that people think LEDs are god's gift to lighting, they actually DO put out a lot of heat when you start to ask them to perform at similar light output levels of conventional fluorescent or incandescent bulbs. They suffer from the same complaint of Fluorescent lights, that they're phosphor based lights, any "white" LED is just a blue LED with similar phosphors as fluorescent lighting, so they suffer from the same problem with color rendering and color temperature. The only benefit they have over fluorescent is that they're a point source of light, which most people prefer.

Save yourself some significant hassle and use LEDs only for hobbyist projects. As a previous moderator of a lighting website, I'll just say that I've spent many hundreds of hours playing with these and other DC circuits and it's not reliable or safe long term. You'll never sell your house if you rig it up with a custom DC led lighting scheme. It will definetly NOT be cheaper by any stretch of the imagination once you consider all of the AC-DC converters, and large gauge copper wire, the complex circuitry for balancing multiple LEDs in parallel etc... Trust me on this one, if you want to string together premade LED rope light go for it, but LEDs DO burn out significantly quicker than they're stated life span due to fluctiations in voltage/current/heat dissipation etc...

 

[bvbellomo]

LEDs are in the 60-70 lumens/watt range

Cree XML's are 1040 lumens @ 10 Watts, being somewhat better lumens/watt with less amps.

Compact Fluorescents at 80-90 is believable but I'd love to see a HID that is 250 lumens per watt.

 

[bvbellomo]

It will definetly NOT be cheaper by any stretch of the imagination once you consider all of the AC-DC converters, and large gauge copper wire, the complex circuitry for balancing multiple LEDs in parallel etc.

You are probably imagining something far larger than I am. This would be for a house (and not a shopping mall), with a single 54 volt driver, no parallel strands, no complex circuitry and no runs longer than 20 feet.

 

[tylernt]

Limit seems to be 50 volts:

http://charmeck.org/mecklenburg/county/CodeEnforcement/Electrical/Pages/Low-VoltageWiring.aspx

So, code requires lights in a room. I don't know if low-voltage lights satisfy this requirement.

 

[Ocelaris]

http://en.wikipedia.org/wiki/Luminous_efficacy

Sorry, 250 is the theoretical max, low pressure sodium are up to 200. Most LEDs are still <60 lumens/watt. When you have done enough circuits with LEDs and had so many burn out, I just don't trust anyone who says they will recoup the gigantic inital investment over 20 years. It's just not realistic, particularly when building your own fixtures, accounting for heat dissipation in such a high wattage LED. To say that you could reliably build an LED fixture cheaper and more reliable than the professionals is a stretch. The technology is there if you have the knowledge to not fry your fixture over the long term, but I don't think it's worth the effort at this point. You also have to consider the ac/dc conversion loss in any of your designs.

LEDs have been getting better for years, but they're still not reliable or cost efficient to best any of the residential fixtures out there. In certain limited circumstances they have a leg up, particularly when you're starting from a DC system (cars) or need a single wavelength (traffic lights), or need pulsing (camera flashes etc...). But efficiency wise, even with the latest LEDs, those are theoretical based on low temps, no ac/dc conversion, and perfect heat dissipation. They're not held up to the same standards as regular lights yet. I'm optimistic, but I just wanted to caution people not to jump on the LED bandwagon with abandon.

 

[bvbellomo]

Sorry, 250 is the theoretical max, low pressure sodium are up to 200. Most LEDs are still <60 lumens/watt.

Not sure I agree, but what *most* of them are doesn't concern me, only the ones I'd use.

Low pressure sodium is not acceptable for lighting a house anyway (cost, scale, monochromatic, etc).

...accounting for heat dissipation in such a high wattage LED.

Is 10 watts high wattage?

To say that you could reliably build an LED fixture cheaper and more reliable than the professionals is a stretch.

If I could build them better and cheaper than the professionals , I'd be selling them. I can build something that looks more utilitarian than what is being sold now at a much cheaper price. There is no market for ugly fixtures you have to hard-solder to install.

The technology is there if you have the knowledge to not fry your fixture over the long term, but I don't think it's worth the effort at this point.

Very little knowledge if any is required - connect 2 wires, if it lights, you connected them correctly.

You also have to consider the ac/dc conversion loss in any of your designs.

Hence the driver mentioned above.

LEDs have been getting better for years, but they're still not reliable or cost efficient to best any of the residential fixtures out there. In certain limited circumstances they have a leg up, particularly when you're starting from a DC system (cars) or need a single wavelength (traffic lights), or need pulsing (camera flashes etc...). But efficiency wise, even with the latest LEDs, those are theoretical based on low temps, no ac/dc conversion, and perfect heat dissipation.

People wouldn't be using them for aquariums if they weren't more efficient or reliable than anything else. When you are paying hundreds or even thousands a year in bulbs and electricity, it pays to do the research and come up with the most optimal solution. When you are just lighting your basement, it doesn't matter as much, which is why most people are still on conventional fixtures.

The wikipedia numbers and manufacture specs are based on a theoretical ideal - lumens per watt with no reflector (measured in all directions) or an ideal reflector (no loss of light). This is a huge factor for florescents, but not a factor for LEDs.


FYI - All of the AC/DC issues mentioned above apply equally to florescent lights - they just have more economical premade fixtures available, so no one would build a custom.

 

[Ocelaris]

What I'd suggest, is build a free standing LED Lamp for now, buy an Ikea free standing light and retrofit the LED fixture into that and see how it does. That's what I did with 35w HID car bulbs, worked great for moving around lamps. The consideration with LEDs is the heat dissipation. In a free standing fixture, you won't have that issue. 10w of heat is a lot of heat if you've ever worked with heat dissipation in building these circuits. I'd look at any commercial designs of similar wattage fixtures and basically just copy that. For 10w of heat dissipation you are talking a good amount of aluminum bonded to the back of the actual LED, you have to consider if that light is in a can light, will the temperature raise? I've had many a white LED's phosphors degrade to a greenish/white tint because they over heated over time.

Actually fluorescents run on a/c power, just different frequencies/voltages etc... so it does not directly apply to LEDs which run on DC. You don't have to chop up the sine wave in quite the same manner as you do when you change ac to dc. I'm not saying there aren't inefficiencies in fluorescent ballasts, my intention was to share the problems I have had with regulating voltage fluctuations when converting ac to dc, and just plain old DC stable power, which I attribute to a significant portion of failed LED fixtures. Ever hear the hum for LED fixtures that are drop ins? That's typically the switching power supply which has exceeded it's thermal limits and harmonics have developed, really annoying. I see that all the time in elevators, people think "wow great, bulbs that will never burn out!" but typically the switching power supply fails or the 8 different fixtures have 8 different shades of white because they've over heated at different times.

Just because people use them in aquariums doesn't mean that they are the best. If you haven't noticed my screen name is based on Percula Ocellaris, so I'm quite familiar with reef aquariums and the technology. Although reef people have some good knowledge, often hobbyists lose perspective on the value of a certain technology when applied to different circumstances.

I'd like to see how it turns out, because I think most residential/commercial LED fixtures are junk, too low Color temp and poor CRI. I wish I had pics of HID lamps I have around my house that are basically what you're looking to do with LEDs. So I'd just not build it into the house at this point.

If you really want to see what applies, download the 2008 NEC code book, it's pretty available in PDF online.