I am working on a article extolling the virtues of low voltage power distribution and I find myself wondering, as Mike Teolis from Colorbeam said, “can anyone give me a valid reason why we need 120 volt infrastructure for a 14 watt LED putting out 1000 lumens?”
I love to geek out on lighting technology and ideas, but admittedly am rather limited when it comes to the nuances of power and distribution. In my first job out of college I built and wired houses, pulling miles of yellow-jacketed “romex” cable from room to room, from light to switch, from receptacle to panel. I loved it, but I quickly ran up against the limits of my intelligence. Every time I had to wire a 3-way switch I had to draw out the wiring on a scrap of lumber so I would get it right. It just didn’t stick.
So when it comes to low voltage lighting power (48 volts or less), I had a few simple ideas of why it makes sense, mostly along the lines of substituting a hundred cheap power supplies that are prone to failing with a few robust power supplies in an easy-to-access utility room. Long term maintenance seemed to be the biggest benefit of low voltage lighting, and as a designer I care more about what comes out of the fixtures than how they are powered. I can deliver awesome lighting at 120 volts or 24 volts or 48 volts. Doesn’t matter.
Or so I thought.
I’m sure I have tested the patience of folks like Mike from Colorbeam and Derek Cowburn of Lumencache as I seek to build a more convincing argument for ditching the traditional 120 volt lighting infrastructure in favor of low voltage power. I have not finished the article, but I did end up convincing myself.
It really comes back to what Mike said…”can anyone give me a valid reason…” and I might edit his comment to end “why we need firehoses to fill drinking glasses with water?” It just doesn’t make sense to overbuild our infrastructure when the likely future is not one of higher electricity usage by lighting but lower.
Building with line voltage wiring is a little bit like building a foundation ten times as deep with ten times as much concrete. It doesn’t make a difference in how the house operates – so long as you have a solid foundation below the frost line, that extra concrete is a bit like taking money and burying it in the dirt. It’s useless.
Wiring up a light fixture that sips 14 watts with enough copper to power 1400 watts is a bit of overkill. But does it really matter? Is there any harm to continuing with the status quo and wiring up our lighting circuits with 14/2 or 12/2 copper?
There seems to be a convergence of three movements that point away from line voltage and towards low voltage wiring.
The first movement is the growth of lighting that supports human wellness. Circadian-inspired lighting is just one element of this movement, but perhaps the best known. Every single LED light fixture that supports color-tuning is inherently low voltage, and most need low voltage control cables. In other words, we can send low voltage wiring AND line voltage wiring to a color-tuning fixture that helps our biorhythms, but we can also do it without the line voltage circuit altogether. As we continue to adopt lighting that follows the natural cycle of the sun, more and more of our light fixtures will require low voltage lighting.
The second big reason to go low voltage is to get better lighting in the hands of more people, the reason our design company exists. Simply put, low voltage power distribution can be less expensive than line voltage. It is tough to find skilled laborers to build all the houses needed to fill the shortage; low voltage wiring can be pulled by non-licensed professionals with less training than line voltage because it is inherently safer. And the cost of the wire itself plummets when adopting low voltage lighting infrastructure, by 50% or more. Imagine a world where disc lights are replaced with color-tunable low-voltage downlights that do a better job illuminating the space and supporting the wellness of the occupants, all without the exorbitant price tag. That’s a future I’d like to see happen.
The third reason is the one I personally find the most compelling: our planet has finite resources. Derek Cowburn ran case studies for Lumencache that found 1200 feet of 120v wiring is used for lighting in a typical home. Substitute low voltage wiring and that goes up to 2400 feet…yet because the conductors are so thin it results in a sixty percent reduction in copper usage.
If we keep wiring our lighting circuits with extra copper, we are mining the copper, refining it, transporting it to factories, pulling it into wires, shipping it to job sites, and installing it…and leaving 50% of its capacity unused forever. We are wasting half of our copper for lighting. We cannot get it back.
Okay, I had better wrap this ramble up. But if I really care about human wellness, better lighting for everyone, and the health of our planet, I should probably be doing more low voltage lighting.
Can anyone give me a valid reason not to?
Read more THINK LIGHT posts HERE.
Read a related post on low voltage lighting HERE, where I spend a little more time on the maintenance discussion.
The biggest reason for not having low voltage is it is duplication. Lighting WAS the driving force for home/commercial wiring in the 1800s, but that ended a long time ago. All the pluggable appliances/entertainment devices/hard-wired devices (garbage disposers, dishwashers, doorbells, etc) drive the need for high-current, 120vac wiring.
The second major reason against low voltage is standardization. Unless there are baseline standards, no industry will be grown around products that use that standard. It goes back to industrial standards for armaments versus hand-made components (that were not interchangeable). It’s the reason the whole world has standardized 12vdc for automobiles and light trucks (with negative ground (earth) forcing the British to change).
The building codes already allow for different boxes/mounting for low-voltage, but that is mainly for non-power wiring – which has also fallen away due to changes in tech.
I think the way forward for lighting is to go with rechargeable battery packs and surface-mount wiring to better accommodate future tech changes. If this were adopted as an industry standard, there would no longer be a reason for any in-wall wiring/boxes for lighting.
Great article, David! I’d love to offer my thoughts on this particular discussion. Call me anytime!
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Will do, George! Thanks for the kind words.
I really enjoyed your article, David. It is an accurate analogy to how things work today. David Eakin had a good point about standards, but I think PoE addresses that today. It is a standard that has been around for over 20 years in the IT field 802.3af/at/bt and gives low voltage to LED lights and data (control) on the same wire. With the latest bt standard being approved in the last two years, PoE can now handle up to 90-100W per economical category cable (Cat6/6A/7 etc.)
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Thanks for the comment, Dusan! It does seem like PoE has gained traction in the commercial sector; that may help us move the needle on the residential side.
There are many loads in a house that are in the sub 30 watt category. Most are in the ceiling. Lights, fans, ceiling fans, smoke detectors, WiFi access points. All these can be wired with class 2 faster and cheaper than 120vac. Not only is there less copper, the reduction in the 600 v insulation to 150v saves plastic so the wire is easier to work with.
Regarding standards, for exchangeable low power loads – like desk lamps, USBc is a widely available mature standard for desk level wall outlets.
For the 18 inch high space heater / vacuum cleaner outlets every 12 ft, and the one-per-house high energy loads – mostly in the kitchen, the duplex outlet will remain for many years.
A battery fed, 350v class4 bus used in data centers today, is slowly appearing in commercial projects, and a Trane VRF hvac with 380vdc was demonstrated at RE+ in fall 2022.
Meanwhile, DC to dozens of ceiling loads is real today. Residential POE isn’t affordable, not to mention that humidity and PoE is a really bad combination in wet areas or soffits.
Finally – implementing circadian lighting with DC is easy and requires zero electronics in the fixture, a single pair of awg 18/2 and no cloud management. Implementing that with 120vac is a management mess.