LED /Low-voltage lighting in new home?

This is the place for any magazine-related discussions that don't fit in any of the column discussion boards below.
User avatar
VernGraner
Posts: 223
Joined: Sun Mar 02, 2003 1:01 am
Location: Austin Texas
Contact:

LED /Low-voltage lighting in new home?

Post by VernGraner » Tue May 19, 2009 4:28 pm

Ok, looking for opinions and/or idea sources. :idea:

I'm in the process of building a new home and I was wondering if it would be worth it to pre-wire for low voltage lighting.. maybe LED lighting?

In my current plans, I am already building to accommodate a roof-mounted solar array (possibly folded into the loan or maybe added later) and will have conduit ready to take the wire from the roof to a wiring closet. After the panels are up, the next usual step would be to place a DC to AC inverter in the wiring closet for a grid-tied system or, if we were to go with off-grid batteries, we would need the inverter to take DC from batteries to 110vac for household appliances etc.

When considering this, it occurred to me that low voltage DC is what the panels natively produce, and converting from low voltage DC to high voltage AC is an inherently inefficient and (for short distances) mostly needless process. A.C. makes sense when you have to step voltage up/down and/or run it long distances, but inevitably most all the consumer electronics in a typical home run on DC (just count the wall-warts in your house!) :???:

Subsequently, I was thinking it might be a good idea to put in some wiring before the sheet rock goes up that could accommodate low-voltage (LED?) lighting. I know that with most devices requiring 110vac or 220vac (HVAC blower, washer/dryer motors etc) won't work with it, but at least the lights would be able to. :cool:

So, anyone else ever done this? Comments / concerns welcome :)

Vern
--
Vern Graner

User avatar
dacflyer
Posts: 4559
Joined: Fri Feb 08, 2002 1:01 am
Location: USA / North Carolina / Fayetteville
Contact:

Re: LED /Low-voltage lighting in new home?

Post by dacflyer » Tue May 19, 2009 9:35 pm

sounds like a good idea to me,,, would be great for mood lighting / indirect lighting , and since its DC it will be great for emergency lighting..and would run for many hrs on end.
just make sure to find a good source for good leds, especially color rendering.. Cree has good leds, build them into your fixture of choice.

i cannot wait til the local power co. here lets me grid tie my 2.2Kw set up here.. Grrrr but they do not participate in green power yet.but yet everyone else does :P

User avatar
MrAl
Posts: 3862
Joined: Fri Jan 11, 2002 1:01 am
Location: NewJersey
Contact:

Re: LED /Low-voltage lighting in new home?

Post by MrAl » Wed May 20, 2009 5:23 am

Hello,


Sounds like a good idea to me too. I do find myself at a loss however as to how much wiring to include...
Every room, or just some rooms?

Now every solar panel is low voltage either though. Some would be higher like 100v or more (DC of course).
I guess it would be a good idea to check that first.
I wouldnt rule out dc to dc down converters either though, if the dc voltage happens to be high.

It can be quite a task to plan the wiring out but im not sure how far you intend to take this.
Put jacks in every room just like AC outlets only with different kind of connector?
LEDs vs Bulbs, LEDs are winning.

User avatar
philba
Posts: 2050
Joined: Tue Nov 30, 2004 1:01 am
Location: Seattle
Contact:

Re: LED /Low-voltage lighting in new home?

Post by philba » Wed May 20, 2009 7:27 am

I would look at this the same way I'd look at using a lighting control system like Lutron Homeworks or similar. Bascially all the lighting loads are wired in a home run configuration (aka Star) back to the central controller. Control wires are run from the switch boxes to the controller as well. We used CAT 5 for our control wires. If you select load wire size to carry the right amount of current, you can switch from AC to DC when the time comes.

This approach can be expensive but probably cheaper than running double the wires.

Phil

User avatar
Bob Scott
Posts: 1192
Joined: Wed Nov 20, 2002 1:01 am
Location: Vancouver, BC
Contact:

Re: LED /Low-voltage lighting in new home?

Post by Bob Scott » Wed May 20, 2009 2:25 pm

Wow, I'd have to think about how much power. If there is intent to run as much power at 12VDC as a regular AC load does at 120VAC, the current required would be 10 times. That means #4 gauge instead of 14 guage wiring.

It's just a thought.
-=VA7KOR=- My solar system includes Pluto.

User avatar
philba
Posts: 2050
Joined: Tue Nov 30, 2004 1:01 am
Location: Seattle
Contact:

Re: LED /Low-voltage lighting in new home?

Post by philba » Wed May 20, 2009 2:52 pm

Clearly, he's not going push 1KW through an array of LEDs so it might just work out for awg 14. Gotta do the math though.

Either way, it means a LOT more copper in the walls...

User avatar
VernGraner
Posts: 223
Joined: Sun Mar 02, 2003 1:01 am
Location: Austin Texas
Contact:

Re: LED /Low-voltage lighting in new home?

Post by VernGraner » Wed May 20, 2009 3:04 pm

Bob Scott wrote:Wow, I'd have to think about how much power. If there is intent to run as much power at 12VDC as a regular AC load does at 120VAC, the current required would be 10 times. That means #4 gauge instead of 14 gauge wiring.
True... IF the watt-to-lumen ratio is the same. :) What I'm hoping for is a vast efficiency increase in LED lighting in the next few years that makes the lumen output at a given wattage higher than incandescent / CFL bulbs, resulting in a lower current requirement for LEDs. Also, there is efficiency gain in not having to use an inverter with its inherent loss.

I was thinking about using 14 gauge speaker wire maybe..? :?

Vern
--
Vern Graner

User avatar
MrAl
Posts: 3862
Joined: Fri Jan 11, 2002 1:01 am
Location: NewJersey
Contact:

Re: LED /Low-voltage lighting in new home?

Post by MrAl » Thu May 21, 2009 1:55 am

Hi again,

Oh yeah we almost forgot an important thing...

It would be a good idea to check what the local electrical code is for low voltage wiring.
There were a number of fires caused by low voltage doorbell transformers in the past
so they might have some strict codes in force. Knowing beforehand would certainly be
a good idea.
LEDs vs Bulbs, LEDs are winning.

User avatar
sofaspud
Posts: 531
Joined: Wed Feb 13, 2002 1:01 am
Location: San Antonio, TX
Contact:

Re: LED /Low-voltage lighting in new home?

Post by sofaspud » Thu May 21, 2009 7:27 am

From the sound of it, 14AWG or bigger ought to do the trick. You could even just run conduit&string for now until
your plans (and that LED efficiency) are better developed.

User avatar
haklesup
Posts: 3046
Joined: Thu Aug 01, 2002 1:01 am
Location: San Jose CA
Contact:

Re: LED /Low-voltage lighting in new home?

Post by haklesup » Thu May 21, 2009 3:11 pm

My first question would be how do you terminate a DC system. In other words, do you just pigtail the wires from a multitude of J-boxes or is there some sort of receptacle you could plug into. Might look funny with 12V car cigar lighter style jacks all over the place.

I suppose I would run one branch to ceiling recessed j boxes and wire nut them until needed. I would run another branch to anyplace you might want to have a PC or networking gear. Separate branches so you can use different voltage if need be. If I had to pick a voltage, I would choose 12V. However, 5V from USB style jacks seems to be an up and coming standard that might be worth looking at.

Sure most things ultimately run off of DC but what DC do you want 3.3V, 5V, 12V, 24V or even 48V (new power over ethernet). Notebook PCs run off all manner of oddball Voltages and external HDD, Routers and modems run off 12V, 5V or even 3.3V. Cell phones charge from a variety of voltages too.

DC-DC converters are complex and somewhat expensive when compared to tried and true AC-DC linear and switching supplies made in vast quantities with reasonable prices (not to mention they usually come with the applicance)

So if you stick with just lighting applications, you can't really count on the voltage being standard there either. All sorts of new driver chips and switchers designed for AC will come with those lamps. You would need to survey the market and get the lamps when you choose the supply voltage. The high brightness LEDs usually are driven from special driver chips (presumably PWM) and not steady state DC supplies.

Its a great idea but the infrastructure and technical standards don't really exist yet. As such you would be swimming upstream and destroying your cost savings by buying things that may not be applicable in the future. Without code standards, you could end up with a White Elephant, it wouldn't necessarily improve the value of the house since the next owner will be so confused as to not use it.

If you want to run extra wires, stick to A/V. Whole house audio and room to room video is useful but even there, what wire to use Composite or HDMI and when wireless video comes of age, what then. Come to think of it, 12V would sure be handy for Car Audio equipment, you could save a lot using a car amp but #14 wire won't do it there.

Before you jump, try attending some of the many webinars on the LED lighting topic. Design news T&MW, EDN, ECN, PD&D (and others) magazines all have specialty e newsletters for LED lighting or ones covering the topic with others. Most of the semiconductor companies also have multiple chips for driving and LEDs for lighting complete with white papers, app notes and datasheets galore. Its very early in that industry now, a wild west scenario for those trying to sort it out now. Good luck.

In the end, you might be better off running empty conduits and pulling the wire later when the choices are more universal. Grey PVC is reasonably priced and easy to work with as a DIY project. Just be sure not to let it become a mouse or bug highway.

One final Note. Title 24 is a must read for anyone remodeling or building a new house, even if you don't live in CA
http://www.energy.ca.gov/title24/
http://www.energycodes.gov/

User avatar
dtief
Posts: 59
Joined: Wed Aug 20, 2008 4:13 pm
Contact:

Re: LED /Low-voltage lighting in new home?

Post by dtief » Thu May 21, 2009 8:16 pm

I've been experimenting with high power LEDs a bit. Some of the best current technology devices are comparable to flourescents for Lumens / Watt. They are better than the worst, but not quite as good as the best. Comparing to 48" T12 & T8 tubes.

I just ordered a 3,500 Lumen :shock: RGBW LED to experiment with.

I ran a 12VDC solar system while building my house. Had about 1000AH of lead acid batteries as the storeage.

For any DC power distribution system, be sure to use fuses or breakers rated to interrupt the DC voltage & power available from the SOURCE, just like regular AC distribution is done.

You will likely find that you need to run heavier wire than the code tables list for 120VAC because the voltage drop will matter more at 12V than it does for 120V.

stevech
Posts: 138
Joined: Mon Jun 05, 2006 10:27 pm
Contact:

Re: LED /Low-voltage lighting in new home?

Post by stevech » Thu May 21, 2009 9:33 pm

I just put in kitchen under-cabinet LED light - Flex printed circuit strips. High end. Cool white. More than bright enough for task lights. Elegant looking. Just 8W or so. Really like them.

Also replaced ceiling florescents and after great study, I went with halogen can lights. Technically illegal by Title 24 in this state - they don't want incandescent or halogen can lights for greening-up reasons.

User avatar
Bob Scott
Posts: 1192
Joined: Wed Nov 20, 2002 1:01 am
Location: Vancouver, BC
Contact:

Re: LED /Low-voltage lighting in new home?

Post by Bob Scott » Fri May 22, 2009 6:21 am

haklesup wrote:In the end, you might be better off running empty conduits and pulling the wire later when the choices are more universal. Grey PVC is reasonably priced and easy to work with as a DIY project. Just be sure not to let it become a mouse or bug highway.

One final Note. Title 24 is a must read for anyone remodeling or building a new house, even if you don't live in CA
http://www.energy.ca.gov/title24/
http://www.energycodes.gov/
After my experience wiring a mobile TV truck, I'd recommend some type of invisible or decorative opening wall panels instead of conduit. It gets almost impossible to run more wires through a crowded wiring conduit. They tend to tangle and pull and bunch up, and conduit wire lubricant is too messy, especially if you make your own wooden conduits.

Thanks for the links Hackles! Now that California is broke (again), can they afford to employ code inspectors?
-=VA7KOR=- My solar system includes Pluto.

User avatar
haklesup
Posts: 3046
Joined: Thu Aug 01, 2002 1:01 am
Location: San Jose CA
Contact:

Re: LED /Low-voltage lighting in new home?

Post by haklesup » Fri May 22, 2009 7:50 am

Thanks for the links Hackles! Now that California is broke (again), can they afford to employ code inspectors?
In my city they simultaniously increased the price for a permit, increased the number of things needing permits and implemented a self serve website to apply and pay for these permits. While the up front cost of the web app must have had an impact, in the long run it should increse the profit margin to pay for those $100k+ city employees. They put in several hunderd new condo/townhome units last year and almost no new commercial property.

Presumably the cost of the permit pays for the inspection which is a city responsibility not the state. That dosen't seem to matter to my next door neighbor who seems to have no concept of what a setback is as he builds whatever he pleases right up against the fence. I checked online, he never has applied for any permits while I have had several. I think he is the only one in the city with an 8 foot fence across the front of his property, at least I can't see in his backyard cause I have this nice row of italian cypress almost 50 foot tall along that border.

I didn't intend to be so pessimistic about DC lighting but I do think the lighting should be chosen first. Might be wise to use 12-2 romex so you can use it for AC if you choose to.

k7elp60
Posts: 226
Joined: Wed Dec 05, 2001 1:01 am
Location: Ivins, UT
Contact:

Re: LED /Low-voltage lighting in new home?

Post by k7elp60 » Mon May 25, 2009 7:56 am

I have been using some DC lighting in my home for about 10 years, and it has been powered mostly by batteries charged with solar panels. I have 3 ea 75 watt solar panels that charge 4ea 6V 225AH golf cart batteries connected in a parallel/series configuration. The primary purpose of the the system was to run my amateur radio equipment. The lighting is RV light fixtures that are mounted on the headboard in the bedroom for reading lights. Knowing that the life of incandescant bulbs have a limited life, and believing that the initial surge on the bulbs affects the life I built a circuit on each fixture to limit the surge current. As of this date the original bulbs are still in the fixtures. I have stayed with the incandescent bulbs for two reasons. 1. I still have a large number of replacement bulbs. 2. I still haven't found an LED that gives the same pleasant light.

Post Reply

Who is online

Users browsing this forum: Google [Bot] and 36 guests