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0 pointsrsync1d ago0 comments

"... throughout my house and observed that other than a few large appliances, the majority of powered devices in a typical home in 2026 could be supplied via PoE DC current as well!"

We installed 120 LED ceiling lights in our home circa 2020, all of which were run with high voltage (romex) and accompanied by 120 little transformer boxes that mount inside the ceiling next to them.

Later ...

We installed outdoor lighting with low voltage, outdoor rated wiring and powered by a 12V transformer[1] and I felt the same way you did: why did we use a mile of romex and install all of those little mini transformers when we could have powered the same lights with 12V and low voltage wire ?

I then learned that the energy draw of running the low-volt transformer all the time - especially one large enough to supply an entire house of lighting - would more than cancel out energy savings from powering lower voltage fixtures.

You don't have this problem with outdoor lighting because the entire transformer is on a switch leg and is off most of the time.

So ... I like the idea of removing a lot of unnecessary high voltage wire but it's not as simple as "just put all of your lights behind a transformer".

[1] https://residential.vistapro.com/lex-cms/product/262396-es-s...

0 comments

eqvinox1d ago

> I then learned that the energy draw of running the low-volt transformer all the time - especially one large enough to supply an entire house of lighting - would more than cancel out energy savings from powering lower voltage fixtures.

That's not a constraint of physics, you can absolutely build a DC power supply that is efficient in a wide load range. (Worst case it might involve paralleling and switching between multiple PSUs that target different load ranges.) But of course something like that is more expensive...

Dylan168071d ago

> But of course something like that is more expensive...

More expensive than an inefficient unit, but it should still be a lot cheaper than 120 separate units, right?

And I expect one big fat unit to do a better job of smoothing out voltage and avoiding flicker than a bunch of single-light units. Especially because the output capacitors are sized for the entire system, but you'll rarely have all the lights on at the same time.

Though for efficiency I'd think you'd want 48v and not 12v.

phantom7849h ago

Plus you save money on the conductors running to the lights.

shiroiuma22h ago

These days, you should not be using transformers to power small loads at all, you should be using switching power supplies. They have negligible power draw when there's no load attached.

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