[monitron]

We're currently in the process of designing a house that we hope to build early next year. One thing that I dream of doing is lighting the entire house with LEDs wired in a low voltage DC "network." Even better if they're addressable, dimmable, even RGB recolorable.

Power over Ethernet would be a pretty cool way of doing it if it was practical...that way you get the data to control the lights as well as the power to run them.

Does anything like this exist in a way that won't get me fired by the builder for even mentioning it?

[mdorazio]

Other commenters here haven't really provided any good data to show the issue. If you want to run, say, 10A at 24V through DC wire on a circuit you end up needing stupidly thick wire (~6AWG) to avoid voltage drops over just 100ft. There are charts available to show you, for example [1]. If you're thinking of running normal hobby wire for 12V circuits around a house, the resistance losses are going to be huge.

[1] https://www.boatus.com/expert-advice/expert-advice-archive/2...

[nick__m]

many post like your's turn around those formulas

  V=RI and W=VI 

combined to give

  WireLossInWatt = RI²

assume a 120W bulb and a 2.5mm diameter 1km long copper conductor (around 7ohm).

  at 120V you need 1A so you lose 1²A² × 7ohms = 7W

  at 12V you need 10A so you lose 10²A² × 7ohms = 700W

That example with a small diameter long cable is a bit extreme but I hope it's illustrative

[dreamcompiler]

What? 12AWG Romex is rated for 20A in normal residences in the US and it's already in a lot of homes, so the retrofit would be easy. And for LED lighting you wouldn't need nearly that much current at 24V, so voltage losses would be negligible.

[Dagger2]

"Rated for 20A" means that putting 20A through the cable will heat it to the maximum rated temperature, which is ~90C for that type of cable.

Heating all of your house wiring to 90C is a) dangerous, and b) expensive. Even if you're doing less than 20A, decreasing the voltage by a factor of 5 still increases energy loss in cabling by a factor of 25.

[danielsju6]

Ubiquiti has POE panel LEDs https://unifi-led.ui.com/ Obviously geared towards offices. I’m sure there are other options.

I’m also looking at whole house USB-PD, https://voltekinc.com/dc-power-advantage/

[gwbas1c]

My house was built in 2018. The smoke alarms are low voltage. I remember the electrician, who installed them, told me they are DC.

Thermostats and doorbells are low-voltage AC. The transformer is standard. If you can find 24-volt AC lights, an open-minded electrician should be able to figure it out.

Related: My old house built in the 1960s had an intercom system that was ripped out by a previous owner. I found a warm transformer attached to a bare bulb light socket in the basement with nothing else running from it. I happily removed it.

[hollerith]

LEDs will flicker (worse than old-school fluorescent lights did) when directly connected to 60Hz AC.

[asddubs]

low voltage is just not a good way to send high amounts of current over even moderately long distances, because low voltage means higher current, which means higher losses to resistance in your wiring, which means you will need much much thicker wiring.

[pomian]

Look into country cabins, boats and campers. Especially the first though. Many are built with only solar for power. They have 12 volt wiring for 12v lights, and 12v outlets. The only AC is if someone plugs in an inverter to a 12v outlet. If course there are many builds with a main inverter next to the ' battery shack', and often 110 AC wiring from that. But there is a lot of information about pure 12v systems, and it is very doable. The problem is if you are not doing it yourself and are in a city, to find a contractor. If you do a dual setup - I suggest using a different colour of wiring, for the 12v system. ;)

[lbriner]

That isn't a great analogy because the expectation for electrical appliances in a boat/camper/cabin is much lower than it would be in most homes.

I had a battery fridge in a caravan (trailer) and it was very small and pretty rubbish, certainly not suitable for home. However, for a short stay, it could keep some basic foods cool enough to be safe.

As others have said, although it is fine on paper, as soon as you start talking about significant power, you are talking lots of amps, which means more risk of overheating and fire, potentially significantly larger (and therefore expensive) cabling and all of the switchgear that can support a few amps AC will not support the same current at DC so all your switchers are larger/electronic. There is also an issue of RFI which could be significant if you are switching high current DC loads.

[jaclaz]

I wonder where the "requirement" for low voltage DC comes from.

At least here Europe/Italy there are bus-based systems from various manufacturers.

Example:

https://professionisti.bticino.it/catalogo-prodotti/myhome-i...

(not too bad in google translate)

Basically normal wires (here 220-250 V AC) Live+Neutral+Ground and a signal (bus) 2 wire cable arrive to each and every electrical box/light point.

Then you can install into the box any kind of device, switches, outlets, etc., and you can configure them.

The bus wires (the protocol is called SCS):

https://en.wikipedia.org/wiki/Bus_SCS

allows also (low power) 27 V DC trasmission.

The protocol and compliant devices were first introduced between 1996 and 2000 and are by now well tested and reliable:

https://en.wikipedia.org/wiki/OpenWebNet

Legrand also uses the same protocol:

https://developer.legrand.com/documentation/open-web-net-for...

[dreamcompiler]

Ignore the naysayers herein. Your power requirements are low enough that 12AWG wire will work fine. Wire your lighting circuits with standard 12-2 Romex, power it with 24VDC, and use LEDs. The only hard part is finding the proper constant-current drivers for your fixtures, but they should be available.

[lazide]

Low voltage electrical is entirely doable and no issues code wise. If you have them run low voltage conduit to wherever you want, you should be good to go.

Just be aware many jurisdictions have minimum lighting requirements that your low voltage lights may not meet, but you could always just leave those lights off

[jwr]

I'm building a house where I'm doing exactly that. LED panels powered from a 48V solar installation.

We'll see how things go, but on paper at least this makes a lot of sense if you don't try to run things at 12V (why do people still try?). 48V is a voltage that is still safe, but cuts your amperage and losses to reasonable numbers.

While designing my own LED drivers, I found that most LED panels will internally work with a Vf of 36V, which you can efficiently get from your 48V installation.

Even in an AC-powered home, if you have lots of LED lighting in one place, it makes sense to use a single high-power converter to get 48V DC and then drive LEDs off that. Small AC to DC converters are inefficient.

[wyager]

Low voltage residential wiring is not very efficient for most applications because the conductors have to be so much larger.

[dreamcompiler]

That's true for incandescent lights. It's not true for LEDs because they need ~10x less power.