Low voltage house lighting

Discussion in 'General Electronics Chat' started by geoffers, Mar 20, 2016.

  1. geoffers

    Thread Starter Senior Member

    Oct 25, 2010
    Hi All,
    We are half way through our new build house and are at the stage where so wiring desicions need to be made. We are off grid so have a bit of a unique situation, we have a large 48v battery bank, generator and solar. I want to use led lighting to keep power consumption to a minimum, I would aslo like to use remote switches, I was considering using (say it quietly) a transformerless supply for each light and triac dimming (with a pic). I've a feeling I might run into regulation problems (uk). Seems to make more sense to tap into the battery and run some 12v dc lines into the house for the lights and avoid losses through our inverter stepping up to 240v then transformers stepping back down for the led's. 12v is much easier to switch and I could pwm a mosfet to dim the lights.
    Am I barking up the wrong tree? Has anyone here got experiance doing this? Will my losses on the low voltage dc cable be enough to out weigh the gain of not using the inverter and led transformers?
    I can get away with short dc runs if I do the remote switchs, compared to quite a lot of 240 ac wiring.

    Cheers Geoff
  2. ian field

    AAC Fanatic!

    Oct 27, 2012
    With the most recent LED bulbs; 13W is just about equal to 100W incandescent.

    For such low power, a simple flyback converter local to each bulb is feasible. Being local it gets switched off by the switch, so no standing current draw.
  3. #12


    Nov 30, 2010
    A quick thought: If LEDs are 10 times as efficient in producing light compared to incandescent, and you're using 1/10th of the voltage you would normally use, the same amount of light would need the same wire size.
    P = IE
    120 watts incandescent = 120 volts times 1 amp
    12 watts of LED light = 12 volts times 1 amp.
    House wiring is decided by the current it carries so both wires would be the same size.
    Running mostly 120 volt circuits and using local regulators is the way to go.
  4. hp1729

    Well-Known Member

    Nov 23, 2015
    I don't know what is available locally for you or what fits your budget but across the pond here we can get120 V LED fixtures that plug into regular housings. Edison bulbs or fluorescent tube substitutes. Large low voltage systems have a lot of line lose.
    If you want to go with individual LEDs ...
    I have been pretty happy with these. They come in 3,000 K and 5,000 K colors. About 900 lm. 9 to 12 V at about 1 amp. I have a 5,000 K one I use as a desk lamp, running at 9 V, with heat sink and fan. It will tolerate 12 V but I have never used it that way.
    Most of my LED lamps run on 120 V AC or 12 V DC. Designed for my son, the survivalist.