LED tape as aisle lights

[MarshallPope]

I've been researching a low-budget replacement for our seat-mounted aisle lights, because the night-light bulbs that fit get left on and burn out quickly and any LED candelabra base bulbs that fit all focus to the tip and emit very little light through the louvered faceplates. The gang boxes in the seats are only an inch or so deep, so it has been fairly impossible to find any replacements that work without spending considerably more than we would like.

I think I have come up with a solution that just may work, but before I formally submit it to maintenance for the electrical portion, I wanted to run the idea by you guys and see if there is anything I have missed.

My plan is to get something similar to this dimmable transformer and have it wired in with a dimmer by the breaker box, converting the wiring to the seats to 12v DC. As far as I can tell, the conduit runs through the floor across the back of the house and down each side of the seating. I'm guessing it is something like a 150' run total, in two branches. It is a 2-wire system, as far as I can tell - at least to the gang boxes in the seats; I haven't opened a box in the floor yet to check, but I think I only need 2.

Once everything is DC, I'll take some generic warm LED tape and cut it in sections of 3 or 6 LEDs. (There are 3 LEDs per cuttable section.) This will be either wired in place of the candelabra sockets in the louvered boxes or recessed under the wooden end-caps, depending on our tests of how much light is emitted from where and what physically fits. I'm guessing that, if we go with putting them in the boxes, I'll also want to throw some diffusion in there so that the point-source LEDs through the louvers don't make zebra-stripes in the aisles.

There are 14 rows, continental seating, so we'll only need 28 instances of this. This should total either 7 or 14 watts, depending on if we use segments of 3 or 6.

Are there any issues with this or anything I should be aware of?

Thanks as always.

 

[headcrab]

Voltage drop could be an issue. Your AHJ also might take issue with components that aren't UL listed.

 

[BobHealey]

How quickly do the bulbs burn out? The first 15W incandescent ones I found on google are rated for ~1500 hours. If you're replacing them more often than every 2 months, I'd wonder if something else might be out of spec, either a couple bad sockets or higher than expected voltage in the lines. Assuming they aren't on a dimmer now, might be worth investing in either a timer switch (one of those turns off automatically after X hours switches), and/or a dimmer/variac to reduce the voltage down to 110-115V, which should help extend the lamp life.

 

[MarshallPope]

I had wondered about voltage drop. IIRC, the wiring is 12ga, so hopefully that would help mitigate it. I'm not sure, though. I'm 99% sure what we have now wasn't UL listed to begin with, and has been modified since installation in the 60s. They are in sad shape. I've even been zapped changing a lamp in them before.

//

We don't have to replace them that often, but we really don't get much light out of them even with the incandescents. I will meter them, though, just to see what is up on that end. I like the idea of the timer switch, and will keep that in mind.


edit: I just ran some numbers through a voltage drop calculator and, with 14ga wiring at 150', we would be looking at just over a 3% voltage drop, with ~11.6v at the end.

 

[ship]

A bit of time with a cordless Dremmel tool might be able to repair your lamp sockets. Requires a silicone fiber bit for the center contact and a brass wire wheel for the screw base, than McMaster Carr 7437k15 electrical contact cleaner with lubricant to clean up the bright work now exposed. Probably arched way out efficiency by now.

If set on your ways in going LED tape, it's an interesting idea and could work even better if high output RGB tape in being able to change the colors or in going white dimmed but also colors for special occasions. Possibly could even get a tax rebate on doing so. Overall if a project you are looking towards... should work out great for this situation.

The cost of going power supply and encoder white or color will not be cheap as with the tape itself. Yes it probably is a good alternative in output in this case for a single strip of it, but over time and if done well should last 50 years. Voltage drop on DC power is different than AC power so study into it. Also the little pads on the LED tape to solder to take time, skil and the proper temperature to solder to in not making a cold solder or burning up the pad. Master soldering to these pads before even attempting such a project. I get stuff from manufacturers that works coming out of the factory but I don't accept at times by way of the above.

That said, it's a percentage, if you have room inside the box and if possible to wire nut or cap splice off to your house wiring, doing a custom order for LED tape in whip lenght is often worth it in letting them solder to the LED tape pads and you just splicing wiring. Most LED tape suppliers will do custom work and it's worth it especially if you provide them time to get it done.

Details... good sales person in say 10% might not work or have bad nodes and in this case you won't be much worried about matching up color temperature, but on large projects it is a problem by way of lot numbers not matching up. That's the job of your sales person to solve in non-working or mis-color teperature tapes. That even sections that don't work properly in sending back.

Great project you have in mind, great idea for the situation you have.

Further ideas, even if the LED tape is using 3M brand VHB adhesive tape.... the LED's do heat up a little or a lot, and or it's a choice of how hard to stick them down verses in doing so also destroy the LED tape. Mention pre-test everything and test as much as possible along the way? On a large project I was working on this week in something like 10' long strips, we did four extra perpendicular strips of VHB tape and five strips of custom made attachment straps for a mechanical fastening also. Granted it's tapes for a world tour and we cannot control the heat in any situation for tape glue failing but it's something to consider especially if sticking LED tape to the back of a cast fitting in aisle light. Perhaps all though it might stick for now, five to ten years from now it might not be stuck in hoping next year they don't come un-glued.

Cleaning the area is good, also is once dried adding super glue behind the tape, but in general how that double stick tape will fix to the surface is important to consider. That and often you only get one chance. Should that adhesive tape peel off the back of your LED tape in a "do again" it also means part of your LED tape is shorting to the frame. Might not notice this right away in working but will become a serious problem later.

The adhesive tape on the normal LED tape is also it's insulator. That's useful at times for splicing purposes in able to access the bottom pad but also if removed or peeled away and bottom pads shorting to frame in even high resistance short.... will be a problem later.. Careful in re-do by way of a re-do where the adhesive tape gets stretched or removed from an area. That's now an area for a potential short.

Often I will apply double stick tape to an area, roll it with a graphics roller, than apply the double stick tape of the LED tape to it by hand pressure. Both than are assumed to be mechanically applied and bonded by pressure glue to glue.

 

[MarshallPope]

Thanks for the input, Ship. Though I've been involved in projects that used LED tape, I've never worked with the stuff myself, so it's great getting the nuts-and-bolts (tape-and-copper?) perspective on it. As much as I'd love to go RGB, I've been asked to go about this as cheaply as possible, and that would require pulling additional wiring through the floor as well as running a DMX line to the opposite side of the building as the lighting racks through quite a bit of concrete and cinder block.

Good information on the tape situations. Luckily, if we go with the in-the-box location, there are some good, smooth surfaces to adhere to, probably with the back-up double-stick method that you mention. If we end up using the under-endcap position, that will be more difficult, as my surface will be either ancient particle board or heavily pebbled cast-something painted with a glossy enamel.

 

[BillConnerFASTC]

Do you have access to a good illuminance meter to measure the output of your tests? It may be better than existing but now will own it and it better meet code - 0.2 fc in most jurisdictions - minimum over entire aisle.

 

[Scarrgo]

Last summer we replaced all of our wheat lights with LED, a theater downtown had replaced there very old nightlight system with these, they added a gel over to keep with the original room design(so I was told) and because plain white was to bright...they work on the AC system.

We have been very happy with the results, the isles and stairs are more visible. We also went with the amber color...

Sean...

 

[David Ashton]

Ship said,
" Voltage drop on DC power is different than AC power so study into it."
not that I know of, for all practical purposes they are the same, ac impedance might be very marginally higher through inductance but so small as to be unmeasurable.

 

[echnaret]

If you don't trust your soldering skills, you can try getting a solder-less connection like this, cutting them in half, and butt-splicing the bare ends to the preexisting wires from the sockets.

http://www.amazon.com/dp/B0062RBR84/?tag=controlbooth-20

That being said, when I used those this summer, I still had to do a bit of soldering on a few to get all the connections to work. They did help cut down on practical assembly time, though.

 

[taptotweet]

Just a thought, but does code in your area allow you to run DC over AC wiring?

We replaced out AC aisle lights with 12v DC leds a few months ago; we ran power through the mains wiring that was previously used, but were then told that we had to fish new wiring as we weren't allowed to run DC over AC wiring.

Just my 2 cents.

 

[Chris15]

but were then told that we had to fish new wiring as we weren't allowed to run DC over AC wiring.

There's no physical difference between AC wiring and DC wiring, so long as the rated voltage is adequate (and that's around insulation), then you can use whatever.
Where you have run into issues with AS3000 would be in segregation - chances are the old wiring was in the same wiring space somewhere are cables that remained at 240v, and that is against the wiring rules (and for good reason...)

 

[BillConnerFASTC]

From a US point of view, essentially same as the Aussie regs. Low voltage generally needs to be barrierd from line voltage - 120 probably in Texarkana. Nothing to do with ac vs dc.