I would argue that this guy does one of the best jobs on custom floating shelves:
The TL;DR is that he routes channels in the shelves and puts USB-powered LED strips in the channel, wired to a battery inside the shelf. The shelf then surfaces a charging port through a hole.

With that said, I'm not at all crazy about his battery powered lighting. I have an electrical outlet below where I want to build my shelves, but I don't know what the "right" and legal way is to permanently wire them. I think it's one of these scenarios:

  1. Wire some kind of transformer or power supply to feed the 5V USB power. But where? Can it be done in the walls? In another box above the outlets?
  2. Same as 1, but a switch or plug has a USB output on the back side, then feed the USB power cables down to it.
  3. A surface mount chase down the wall with a plug into the outlet, which will look crappy.
  4. Something else I'm not clever enough to have thought of.

I don't want to do anything hacky either that runs afoul of basic electrical code or safety. What's my move here?

  • There are USB plugs on wall outlets, you will see the cable
    – Traveler
    Feb 1, 2023 at 6:35
  • 1
    A) can you summarize "this guy's" video and what you like about it - videos disappear all the time and without a summary here, the link will become useless (also, not everyone will/wants to go watch a video of unknown length to determine what you like about it). B) Do know that there is no way to plug in a USB "wall-wart" inside the wall to completely hide it - that is definitely illegal! We have plenty of questions here asking about doing that and they all have the same answer: No!
    – FreeMan
    Feb 1, 2023 at 14:07
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    @FreeMan, edited the question. I get the legal thing, but at the same time, low-voltage lighting exists everywhere, so there has to be a solution to this, even if it means there's a DC transformer on the lighting itself. In that case, the question becomes, how do you wire that to code to the shelf?
    – Jeff Putz
    Feb 1, 2023 at 14:10
  • The LV transformer can be somewhere else entirely, such as the basement. It has to be accessible, wherever it is, since it has line voltage connected to supply it with the power to make low voltage.
    – Ecnerwal
    Feb 1, 2023 at 16:08

2 Answers 2


LV wires can be routed through walls and hidden as you wish. You just want an invisible way to supply power to these wires.

Invisible: use an outlet in another room eg the basement.

Almost invisible: install a recessed outlet, plug a wall wart into it that fits entirely inside, and route its LV cable however you want. Cover the recessed outlet. Alt: Build a small niche with a cover and an outlet inside. The covers must not be permanent. Think of them as doors.

A couple of examples, but there are others and as mentioned you can build your own niche. These both have holes back into the wall for the LV wire. You'd have to shop around for a recessed outlet and suitable matching PSU that fits inside the recess and is large enough for your lights, and use some creativity to cover them in a compliant (non-permanent) way.

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  • Said outlet can be within the cabinet!
    – FreeMan
    Feb 1, 2023 at 14:49

As for Legality there are all permitted since it is very low voltage.

Change the wall plug to a type that has already USB from which you can run a USB cable to under the shelf, and then from lamp to lamp under the shelf.


Pay attention to the total power the lights need, not to exceed the USB outlet power

The only part you would see is the USB cable running from the wall plug up.

There are nice looking wall conduits to hide the USB cable.

  • 1
    Be exceptionally careful buying electrical parts on Amazon. Much of it does not meet UL standards and is not UL certified.
    – FreeMan
    Feb 1, 2023 at 14:50
  • 1
    Though be careful of a lot of the stuff that's sold on Amazon, as a lot of it doesn't have UL approval, which basically means there's no safety approval for what is being sold. USB wall outlets are available at just about any home improvement or hardware store which WILL be UL-approved. Might be a few dollars more, but worth the peace of mind.
    – Milwrdfan
    Feb 1, 2023 at 14:51
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    @Milwrdfan I figure if you are buying brand-name stuff from Amazon (ideally with Amazon also as the supplier) then you're generally OK. It's the stuff with the made-up brand names like NEATOCOOLFUN that are junk. The margins in making fake Leviton or Hubbell stuff just isn't there when you can sell 100 of them under a fake brand.
    – Chris O
    Feb 1, 2023 at 17:17

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