I have a 12'x15' room to which I'd like to add cove lighting. There's a second floor above, so I don't have access from above. I do have an outlet along the wall where I can tap off for 120V power, and run any wiring up inside the wall to the top.

I will be building the cove, essentially a T-section. I anticipate about 2" of head room above the top edge of the cove.

My issue is, where can I hide the power adapter that converts the 120V AC house power to 12/24V DC for the LEDs? I suppose worst case I can cut a hole near the outlet for an access panel (or blank wall plate) painted to match the wall, and stuff the power adapter in the wall.

Anyone got any other bright ideas?

  • 1
    "Stuff it in the wall" it may be time to learn more about the Electrical Code... glad you are here... Jan 2 '20 at 19:44
  • @Harper-ReinstateMonica: what part of the NEC disallows transformers from being located behind access panels?
    – Huesmann
    Jan 2 '20 at 20:04
  • 1
    This question has come up a few times, and I hope we get a good answer on how to transition from 120v to 12v inside the wall or in a few switch-sized-boxes.
    – JPhi1618
    Jan 2 '20 at 20:09
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    @Huesmann, Here is an answer that cites the NEC section stating that a transformer or low voltage wire can't occupy the same box as "high" voltage electric cables. So it's not that a transformer can't be behind a panel - you can't have it in the same box as 120v, and all wiring connections must be done in an approved enclosure, so you can't have loose connections inside the wall.
    – JPhi1618
    Jan 2 '20 at 21:00
  • @JPhi1618 but that wouldn't preclude a transformer behind a panel that was adjacent to the outlet. The 120V wires from the transformer could be routed into the outlet box and pigtailed in. That way the 120V and 12V don't occupy the same box. No?
    – Huesmann
    Jan 3 '20 at 14:41

I invite other answers, but since you mention cove lighting specifically, there are slim transformers that are made to be easy to hide like this model:

LED driver

Armacost 12v LED Driver transformer

To use this, you could have a 120v standard electrical box behind the molding where the NM cable would exit the wall and attach to the transformer. I'm not sure exactly how to make the transition from the wall to the transformer in a 100% by-the-code way, but the electrical contacts are covered and since it is cove lighting, the connection will be inaccessible to anyone that wanted to touch or snag the wiring.

The transformer would be easy to hide in the "tray" of the molding and comes in different output wattage depending on your needs. Now, I've never used this model and I'm certainly not trying to advertise it - I'm just pointing it out as an example of the slim-profile transformers that are available.

  • Yeah -- it appears to be a self-insulating style of device as permitted by 300.15(E), which means it doesn't need a box at all unless you want to put it in a wet location, which of course would require a box meant for a wet location Jan 3 '20 at 1:28
  • It looks like something like that still needs to be located outside the wall though. It's slim, but still 6x4x1.3, which is a little bulky to hide above a cove.
    – Huesmann
    Jan 3 '20 at 15:04

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