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Can anyone direct me to the best information on wiring a new residence for 100% LED lighting?

Caroline Di Diego | Posted in General Questions on

I am looking for LED wiring 101 ~ What are wire gauge options, voltage regulating options and what are the things to watch out for?

I understand we are still very much in a hybrid AC/DC universe and AC has to exist for kitchen appliances, and infrastructure appliances in the Utility room, however our client wants to take the step into LED. The house is around 1600sf and one floor.

Unfortunately I’ve had difficulty finding a good resource so thought I would turn to the experts here as I am also interested in hearing about any positive or negative experiences with wiring for LED and LED lighting?

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Replies

  1. Thomas Stone | | #1

    You might be overthinking this. There is no need to do anything out of the ordinary. My house was built in 1957 and has been converted to nearly all LED lighting. What did I have to rewire? Nothing. After some experimentation, I can recommend Cree and Philips as reliable brands, but not the new low price-point versions. The Philips BR30 flood is excellent and the Cree A19 60 watt equivalent (not 4Flow or TW) is great in table lamps. For me, the Philips bulbs have performed better on dimmers. Try to avoid can lights in the ceiling of that one floor house!

  2. Charlie Sullivan | | #2

    Agreed. Although inherently LEDs run on DC, the high-quality end-use products are all made to run on AC. The current draw on an LED light on an AC circuit is small, so in theory you could use smaller wire than normal wiring for lighting, but in practice you can't go smaller than is allowable with a standard 15 A circuit breaker, so you'll be wiring it the same as for any other lighting.

    So it's only when you select bulbs or perhaps fixtures that the LED intent matters. LEDs are still improving rapidly, so I wouldn't recommend fixtures with built-in LEDs that lock you into that technology--I'd buy standard fixtures (not recessed cans of course, so as to avoid air leaks), and outfit them with LED bulbs.

  3. Caroline Di Diego | | #3

    I’ve been speccing LED fixtures for 6+ years now. There is now some really great product out there and I can do the entire house lighting with actual LED fixtures (That’s what the client wants) and they like our design focus with indirect lighting everywhere:-) or light source hidden:-) My thought was to have a central device near the service panel instead of multiple transformers ~ seems obvious…….and much cleaner design. Obviously there will be AC throughout the house for 110/220 outlets and appliances. Since this an opportunity to start from scratch I want to find the best “way to go” currently available.

  4. User avatar GBA Editor
    Martin Holladay | | #4

    Caroline,
    Engineers have been touting the advantages of wiring homes for DC power for over a hundred years, ever since Thomas Edison lost the AC/DC battle with Nikola Tesla. There are still a few engineers lobbying for DC wiring -- most recently, I heard Paul Savage from Nextek give a presentation on the topic at this year's NESEA conference in Boston -- but these engineers don't seem to be gaining any ground.

    DC advocates can't even agree on a voltage, so I wouldn't be putting all my eggs in one basket if I were you. Stick with AC wiring.

  5. Mike M | | #5

    I would still think for ease, it would be much better to run 110/120 AC to each area and use a transformer there if DC is wanted. Even if you have a central transformer, you'd have to have a DC protection panel with fuses or breakers to protect all of the DC wiring. You would also end up with two sets of wires running to each area, one for the AC receptacles and one for the DC lighting. I think this would be extremely cumbersome and more difficult to retrofit or alter later.

    The main area I have seen DC is being used for high voltage transmission because there are less losses associated with hysteresis and charging currents as the current changes direction in AC. These do require large converter stations and the wiring and DC machines are all significantly bigger than a similarly rated AC counterpart.

  6. Charlie Sullivan | | #6

    For indirect lighting, an LED fixture makes more sense to me than it does in a standard fixture--you can hide LEDs more easily. I still think it's a bad time to invest in a 60 lm/W fixture when in a few years you can probably get > 120 lm/W efficacy.

    But that's not the question you asked--you asked whether it could make sense to centralize the AC-DC conversion. The voltage you choose might depend on the fixtures you like, but it will probably be 12 V or 24 V. For the same amount of power, those lower voltages require bigger wire (or have more loss with the same size wire) compared to 120 VAC. So distributing the conversion makes more sense in that respect. Also, power supplies have standby losses. If you switch the 120 V off with a conventional switch, that goes to zero. If you have a central power supply, it's on all the time, so you maximize standby losses. Another disadvantage of a central system is that if it fails, all the lights quit. Having one "burn out" is much more tolerable, especially given that the power supply is not something you can buy at a local hardware store.

  7. Alok Khuntia | | #7

    Caroline, what did you end up doing in this project? Do you have any experience with Lumencache? They run cat5 to each fixture from a central controller. I am curious to hear your thoughts as i am considering whole house LED also.

  8. Laurel Davison | | #8

    How about Power over Ethernet (PoE)? is the capacity sufficient for lengths of LED ambient lighting, task lighting and device charge applications? How about the future of DC powered appliances (thinking TV currently)?
    Category 5 cable uses 24 AWG conductors, which can safely carry 360 mA at 50 V -per Wikipedia PoE

  9. User avatar GBA Editor
    Martin Holladay | | #9

    Laurel,
    0.36 amp x 50 volts = 18 watts.
    So, at maximum capacity, the cable can handle one or two LED lamps.

  10. Steve Knapp CZ 3A Georgia | | #10

    Laurel. If you plan to dim your LEDs, find out in advance which switches the manufacturer recommends. Not every switch works with every light. Some lights require expensive dimmers (think $30+ each) to work correctly.

  11. Kenneth Gartner | | #11

    Folks, I enjoy GBA quite a lot.

    However, LED lighting is one clear area where "energy efficiency" dominates over "human health" in these discussions. LED lighting is not equivalent to "efficient incandescent", except superficially. There are many LED downsides that have longer term costs (think: electromagnetic smog, excessive blue spectrum that causes cellular oxidative stress, lack of red and near infrared spectrum, etc). The suggestion to use a dimmer is a unintentionally harsh one since the pulse-width modulation for LED dimmers has demonstrated cellular health risks. A small way to diminish LED downside would be to run them on DC instead of AC, though not just to save money. I, too, am interested in how to cheaply setup some DC wiring in a new construction, along with the normal AC wiring.

    I think the building scientists, who usually are thinking the best ways to build healthful houses, are merely ignorant of such dangers. In hopes of raising awareness, I suggest this podcast episode for those who want to take a deeper look "The Dangers of LED Lightbulbs". https://youtu.be/K1mHTpdEWm8

  12. Trevor Lambert | | #12

    It is my understanding that low voltage cable is of no interest to the electrical authority. As long as you meet all the wiring requirements for the code (which might require a minimal amount of traditional light fixtures, you should have no problem adding low voltage DC lighting to your heart's content. Confirm with your local inspector first, of course.

  13. Steve Knapp CZ 3A Georgia | | #13

    Kenneth,

    Don't most LEDs use a DC power supply?

  14. User avatar
    Dana Dorsett | | #14

    The spectral emissions of low frequency EMF from simple thyristor based dimmers running tiny loads like LED lighting have such little punch behind them that it's ludicrous to be talking about health risks. Even running incandenscent loads at 5x or more power (for the same amount of visible light) have emissions so low that it's a "who cares?" scenario. The assertion that there are "...demonstrated cellular health risks..." associated with the use of dimmers with LEDs is a serious stretch.

    Not all LEDs are heavy on the blue, even though some first generation LEDs using phosphors on blue LED dice were. Almost none of the current middle range products out there are as heavily in the blue as the long standing argon-mercury fluorescent tubes that have dominated office lighting for decades. The electronic ballasts of T8 tubes put out an order of magnitude or more low and mid frequency EMF power than LEDs on dimmers.

    The fear mongering of Mercola & Wunsch is the stuff of snake oil self promotion, borrowing on bits of actual science to build a grant theory of doom that they're going to save you from.

  15. User avatar GBA Editor
    Martin Holladay | | #15

    Kenneth,
    Anyone who gets their medical information from a YouTube video featuring Dr. Mercola is making a grave mistake. For more information on Dr. Mercola, see "Dr. Joseph Mercola Ordered to Stop Illegal Claims."

    "Many of Mercola's articles make unsubstantiated claims and clash with those of leading medical and public health organizations. ... In 2005, the FDA ordered Mercola and his Optimal Wellness Center to stop making illegal claims for products sold through his Web site."

  16. User avatar GBA Editor
    Martin Holladay | | #16

    Dana,
    You beat me to the punch by one minute...

  17. User avatar
    Dana Dorsett | | #17

    Yeah, but in the rush to beat you I misspelled "grand" as "grant". :-)

    Whatever- cat-crap wrapped in a thin veneer of science still isn't worth much, even if it's German-accented cat. ;-)

  18. thrifttrust | | #18

    I wanted high CRI (color rendering index) lamps for my new bathroom. I found these from Green Creative. They mount in standard J boxes but look like can lights. The 90 CRI is great but there is a bonus. Many LEDs will not dim much, or if dimmed too far will not turn on then next time the switch is thrown until the dimmer is raised. Special LED dimmers have a threshold adjustment to fix this but this also limits dimming range. The Green Creative lights work with the threshold set to minimum. They dim so far that we use them as night lights.

    Strip lights are slightly less efficient than individual lamps but offer versatility. I mounded a strip to each cabinet flanking the "floating" lavatory mirror. The indirect light is a nice effect. These also have a high CRI. Strip lights typically have low power LEDs to keep heat down but have different LED densities. These have two rows of LEDs spaced about 1/2" apart. They are bright. Strip lights run on 12 or 24 VDC. I used a transformer type power supply and a "magnetic" dimmer. Unfortunately when dimmed the lights strobe or "shimmer". I added a 10,000 μF computer capacitor to the power supply output to smooth the light output. Like the overheads they also dim to a very low level.

  19. Davidab | | #19

    I am experiencing new construction. Say I want a dozen 'can' lights in my living room. Why not have one Driver that would be capable of driving a dozen LED's rather than a driver for each light? This would also allow less expensive wiring to be used in that room . Are there such drivers available? Is there an overall cost benefit to such a plan?

    1. Trevor Lambert | | #21

      Multi channel drivers do exist. They are not common, and for that reason likely to be expensive. You will have a hard time finding driver-less "can" lights, too. If you find them, they are likely to be more expensive than their driver-included counterpart. So yes, possible. More work, more expensive. The amount you would save on the wiring is going to be a drop in the bucket compared to the increased cost of the driver and lights. If this was a mass market thing, it would probably be cheaper to have one driver feeding multiple lights. Cobbling it together yourself, I don't think so.

  20. User avatar GBA Editor
    Martin Holladay | | #20

    David,
    If you read all of the comments on this thread -- a thread which incidentally is 4 years old -- you'll discover all of the arguments against DC wiring. Stick with AC.

    Contrary to popular belief, low-voltage DC wiring (for example, wiring for 12 volts or 24 volts DC) needs to have a bigger wire gauge, not a smaller wire gauge, than 120-volt AC wiring (assuming loads of the same wattage).

    1. Trevor Lambert | | #22

      Martin,

      All other things being equal, yes 12-24Vdc requires bigger wires than 120Vac, i.e. to carry the same load. But the smallest wire you can use by code for residential AC is 14/2. That wire size can handle 15A. For a circuit of say 8 LED light fixtures at 12W, that's 96W. At 24V, that is only 4A. So you could certainly get away with 18 gauge wires for that application. However it's not clear whether that would actually be cheaper. The volume of sales of 14/2 wire makes it pretty cheap. At best the difference is going to be barely more than negligible.

      1. User avatar GBA Editor
        Martin Holladay | | #23

        Trevor,
        I agree. My off-grid house is wired with two voltages in every room -- 120 volts AC and 12 volts DC. The AC wiring is all 12 gauge, while the DC wiring is 10 gauge. Needless to say, the DC wiring cost me more than the AC. But wiring an off-grid house is a little different from the subject at hand -- a few LED light fixtures.

  21. Davidab | | #24

    Many thanks everyone, all the responses contain valuable information. Of course since P=VI, for a given power load a lower voltage will mean a higher current is required! I was not thinking about this.

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