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I'm planning a project to add RGB lighting to the inside of my garage door. It will add white light to the garage when I need it, as well as visually confirm door motion and position, and clearance of the doorway when complete.

One aspect though that I'd like suggestions on, is how to physically electrically connect the large moving door to the stationary house.

1) The three options I've seen so far would be a horizontal cable festoon: cable festoon

2) Curly cord flat against the wall from the midpoint of the door to the corner of the ceiling. curly cord on garage door

3) Using non-conductive roller wheels for the door, and using the two tracks themselves as conductors with 'brushes on the door' that would ride in contact with the rails. I'd be a little concerned about corrosion over time if this was DC, and the effect of a large looped field if it were AC.

With any of these I will almost certainly be using current-limited 12 or 24v, so that when it eventually breaks I don't have to worry too much about an electrical hazard. Perhaps tension rated break-away connectors would be a good idea to to avoid damage.

The control module will probably be a raspberry pi, mounted on the door. It will probably use wifi for its data connection. But it would be nice to use hardwired ethernet if that wasn't much extra hassle. A festoon for example could accommodate power and ethernet with little extra headache.

My primary concern is physical durability and the likelyhood of cables getting snagged and breaking or blocking the operation of the automatic door opener.

Actually the door opener itself, having a rail and a plastic trolley, might serve as an electric path without having to add any physical objects that could add a snag hazard. As could the torsion spring wires....

Anyway. What other means can you come up with to bring power to my garage door, and what method do you think is the best and why?

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  • will you need the lights on when the door is up? if not, it can be a bit simpler: Al tape contacts at bottom of door meeting the floor. Pi seems way overkill for LEDs but should work.
    – dandavis
    Commented Jan 14, 2018 at 21:20
  • Yes. I envision the light bar flashing red when the door starts to go up, and flashing green when it's high enough that my vehicle can fit under. Rpi would process downward facing video to verify no obstructions to the door's path, and if the door stayed open for too long without and motion through the door way, it could text me, or blink lights on my home automation network to get my attention. I could perhaps see having a lithium battery on the door. Then charging contacts that would engage at either end of the doors travel. But a battery has it's own risks and maintenance cost
    – Billy left SE for Codidact
    Commented Jan 14, 2018 at 21:41
  • Wont ever be too dark, with one or two strips of high density leds immediately above. I might paint lines on the floor, and if say 95 percent of that region is within 5% of the designed color. Then it reads as clear. Very hard to do while moving, but easier if the check always occurs when the door is fully up. And if it's not fully up and not fully closed, then it's almost certainly opening which I wouldn't worry about instructions, or closing, during which the existing beam would protect against, and I'd almost always be present anyway.
    – Billy left SE for Codidact
    Commented Jan 14, 2018 at 21:56
  • In brightness yes, but not too much in hue. Regardless, I'm hoping to keep this question to physical cabling.
    – Billy left SE for Codidact
    Commented Jan 14, 2018 at 21:59
  • Will the door spend long periods of time in the open or partially open position?
    – Harper - Reinstate Monica
    Commented Jan 15, 2018 at 21:16

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You have two components which may be electrically isolated from each other if the door itself is not metal: Tracks and spring/counterweight mechanism; and The opener track. You can make one positive and the other negative. You will have trouble electrically separating the tracks and springs from each other. Keep in mind that spring preload is dangerous, cannot be reasoned with, and does not know pity or remorse or fear.

However, I would be more inclined to use induction, or "two halves of a transformer". Place one half on the door. Place the other half where the door is in the down location. If you only need the lights to to work in that position, you are done. Otherwise either a) have a second "transformer" primary in the open position; or b) install a large enough battery on the door. NiCd D-cells are a good choice, because it is not expensive and rides through abuse better than most. A protected lithium might also do. Presence or absence of AC would also be a means to detect door position.

Keep in mind with transformers, the carried wattage decides the mass of copper, but the frequency decides the size of the iron core.

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