I have used 12V LED lights on my mtn property for more than 5 years now. Since I have a few PV panels and batteries, but no AC (except through the inverter), I have a limited experience. Still, none have burned out nor have the batteries given up. I have 5 lights that I use 3 or 4 days a week. They are all in the 2-6 watt range.

When I started using 12V LED lights, it was on just an old tractor battery that would not start the tractor, due to it's age and poor condition. Two lights lasted all night with no problem from the weak battery. So I bought more, added PV panels (45 watts total), and set up the mtn space with 3 more LED lights.

Yesterday I was at Micro Center. They had a selection of 110volt LED's bigger than the big box hardware. A 65watt, 800 lumen bulb for $17 was the brightest. The 65 watt number was not the bulb's, but the package.

LED's on AC need a surge protector. The only ones I had burn out were not on a surge protected line. Due to the cost, the burnout ended my usage of AC LED lights on lines not surge protected. I have a 1 watt AC LED light that has been on (never off) now for 4 years.

All,

After purchasing a solar LED motion detector light from HomeDepot it sparked an interest to convert all the lighting to my house to DC LED based on solar and battery backup. Does anyone have any resources or a write up in which someone converted just their lighting in their house to a solar and battery setup? It seems with LED bulbs taking very little electricity that this could be done with a relatively small setup and wouldn't require a vast array of panels or batteries. I'm also married with a wife who doesn't exactly support my "geek" activities so I was thinking about doing some type of LED recessed can setup. Can someone point me in the right direction? Resources or anything? Thanks in advance for your time.

-Jeremy

I would start with a calculation of how many dollars are involved. And the effect of a long period without much sun.

I would like to build a new home with only 24V DC wiring from solar and have no connection to electric utility. NEC 690.10 implies that I have to wire my house as if were connected to the utility. My motivation for having no utility hook up was to save money on AC panel box and house wiring. The savings could be put into panels. Has anyone found a way around this aspect of 690.10?

Building codes exist in part to protect all future owners and users of structures. A future owner might not share your enthusiasm for AC-less living.

Anyone here have experience with LumenCache?
http://lumencache.com/

I am bout to start rough in elect and plumbing and am seriously considering this system. Would really like to get some real life feedback. Pretty cool to think all your LED lighting can be accomplished with CAT-V wire and RGB connections. Low voltage no inspection required.

Thoughts?

Drew

I also am wondering what peoples ideas are or experiences are with Lumencache. It is an interesting product. Anyone know anything about it?

AC LED bulbs run off an inverter may be short lived. Most of these use a switching power supply to develop the DC the LED requires from the AC input. They really need the sine wave shape of commercial or generator sourced AC. Most inverters are modified square wave and lack that good sinewave shape(unless you pay a lot for the sinewave output type). This will be very hard on AC led's and CFL's... If i was DC based, i would stay with DC based lights to take the two conversions out of the process. Each conversion has loss...

Posted By ntor on 22 May 2012 11:39 AM
  Besides, when was the last time you saw residential(or commercial) Ethernet wire run over a few hundred feet?

The reason for that is, I believe  propagation time. ie once the cable gets over about 300ft long, the sending computer(or whatever) times out before the signal gets to the far end and a response is sent back. Based on this the max allowable length for a cat5 or 6 cable is about 300ft.

The specifications for 10BASE-T networking actually specify a 100 metre length between active devices. This allows for 90 metres of solid-core permanent wiring, two connectors and two stranded patch cables of 5 metres, one at each end.

It is however possible to add repeaters in the line to go 'longer'. ;-)

There is a reason that power companies use high voltage and then step it down to 240V or more specifically three phases of power which ends up as 240v / 120v in your house. They use AC high voltage to overcome electrical resistance to send the power long distances.

And when they need to send really long distances, they use high voltage DC.

Posted By colinmcc on 24 Jun 2013 06:36 PM

Posted By ntor on 22 May 2012 11:39 AM
  Besides, when was the last time you saw residential(or commercial) Ethernet wire run over a few hundred feet?

The reason for that is, I believe  propagation time. ie once the cable gets over about 300ft long, the sending computer(or whatever) times out before the signal gets to the far end and a response is sent back. Based on this the max allowable length for a cat5 or 6 cable is about 300ft.

The specifications for 10BASE-T networking actually specify a 100 metre length between active devices. This allows for 90 metres of solid-core permanent wiring, two connectors and two stranded patch cables of 5 metres, one at each end.

It is however possible to add repeaters in the line to go 'longer'. ;-)

It's not a timing/digital handshake issue, it's a signal attenuation issue. Ethernet signaling is in packets with the digital clock embedded in the first bits of the packet. Twisted pair cabling is pretty lossy at 100Mhz signaling, over 20dB @ 300meters which is a LOT, and has corresponding crosstalk between the pairs. The amplitude at the receiving end can fall into the noise floor or above the signal levels of one of the other pairs if you take it too much further than spec, but it has nothing to do with the actual velocity latency of the cable. (The speed of light is still pretty fast in cat-5, about 2 x 10⁸  meters per second rather than 3 x 10⁸  meters per second in a vacuum.)

Hi - I have stubled upon this topic and am interesting in bringing it up again, but my interests have nothing at all to do with lighting. Rather, I am building a house soon and am looking for solutions to redude or eliminate the wall warts throughout the house. As you know, most consumer electronic products nowadays are standardizing on a USB connector and 5v+/- for charging. There is a new spec being developed for USB charging that will allow up to 100 watts of power (See here for more details, http://www.economist.com/news/international/21588104-humble-usb-cable-part-electrical-revolution-it-will-make-power-supplies). In my opinion this is the future of devices, and in my new build I want to set my home up ready for it. I am looking into solutions that would involve having a USB port or possible two on each outlet in the home. Outlets with these kinds of ports are already available - what I am NOT sure of is the wiring to bring the 5v back to the panel, and a power supply. What kind of wiring would you use for this? I am trying to gather as many details as I can so I can bring them to my contractor.

Standard USB delivers very few amps, so it can be quite small. Like two conductor telephone wire. But you might as well do barrel plugs too.

But this is not standard USB.... 5 volts at 100 watts means 20 amps, does it not?

OK so I did some reading on the spec and it looks like this. PROFILE 1 5V @ 2A PROFILE 2 5V @ 2A, 12V @ 1.5A PROFILE 3 5V @ 2A, 12V @ 3A PROFILE 4 5V @ 2A, 12V, 20V @ 3A PROFILE 5 5V @ 2A, 12V, 20V @ 5A So looks like I need to be able to handle 5 A? What kind of wire for that. This tool http://www.solar-wind.co.uk/cable-sizing-DC-cables.html says I would need a 1AWG for a 25m run! That is pretty damn thick wire. This idea maybe is a non starter.

22 awg can handle the amps, but you need to specify an allowable voltage drop. For example, 10 gauge wire would drop .45 volts (not too bad). http://wiki.xtronics.com/index.php/Wire-Gauge_Ampacity

sorry to bring back an old thread but I was considering something simmilar for a stand alone electric system, I'm glad I came across this as you all have dug into some specifics allready.

I was considering wireing the lighting in low voltage DC white led run about 3.5v further more learned a solar panel is made out of half volt modules and a custom build could give you pretty much any voltage you desire, lifepo4 batteries have a nominal operating 3.2v empty 3.6v full, I have experimented some last fall but at the moment it was just a thought, the solar gurus seem to disagree, put putt all these together you can have a standalone lightoing system,

again same can be aplied to computers TV even fridges some are 24v , and welders I am pretty sure are low volt high amp, on the output side

OMG. There is a reason things are done a certain way. 1 watt LEDs are used in display cases and sometimes under counter. More often, you will need a 3 watt LED undercounter and maybe for task lighting. A 7 watt LED is about reasonable to put on the ceiling and still have it give some light to the floor. In your 3.5 volt system, that means 2 amps. 3.5V X 2A = 7W. Run your 22AWG wire up from a switch to the ceiling, out to the light and back and you've got minimum 20 feet of wire. The voltage drop on your little circuit is going to be 1.29 Volts or 37%

The same setup in 12V will be 12V X 0.58A = 7 W. The voltage drop will be 0.37V or about 3%. You get one luminaire per run.

I have a pair of brutalicious 12V sump pumps that are operated by a weenie little 14 AWG wire. That's if they sit right next to the power supply. Stick them 40' away and you go up to #4 battery cable.

The funny thing about lighting technology is that with 100 lumen/watt LEDs instead of 10 lumen/watt incandescents it takes the same current, and the same size wire to deliver the same lumens with the LED with 12VDC that it took with the 120VAC with incandescents.

But when you're talking 3.6V power distribution the wire requirements get very heavy, which is fine as long as you own the copper mine (and the smelter too. :-) ), or your are just fine living in the dark. Even at the theoretical maximum ~250lm/watt you'd still have some comparatively fat wire to deal with.

There's no advantage at all to going ultra-low voltage, but there are safety issues at 75VDC and higher, since it can be harder to let go of than 120VAC should you happen to make yourself part of the circuit.