# 120 to 12v conversion

I have 4 flourescent stairwell lights I would like to convert to low voltage LED. The existing lights are on a dedicated circuit. What I would like to do is mount the low voltages power supply at the breaker panel and use the existing wiring and 3 way switching to distribute the 12VDC to the LED lights. The circuit draws olny about 400ma of current on the 12v side so I intend to place a cartridge fuse on that side. Also I would like to place a fuse on the 120VAC side of the power supply as I have seen these power supplies smoke without tripping a 15 amp breaker. Are their any code problems with doing this
Jimmie
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Jimmie D wrote:

Hi, You can get 120V LED light of various colors and shape.
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If you pull (separate) the existing 120 volt wiring completely from the circuit breaker panel; and assuming there are no other 120 volt wires/switches etc. in those same switch boxes. Also that there are no other 120 volt lights on that same circuit, one supposes that you could use the conventional and existing wiring for low voltage? But it could very confusing in the future even if the circuit was clearly marked in each box as 'low voltage'? One could also be concerned that since lighting loads are quite low, a typical 15 amp 14AWG circuit is capable of 1800 watts of lighting (in our house several rooms are on the one 15 amp lighting circuit breaker!) that your intended same wiring also feeds 120 volt lights in say a bedroom etc.? Ingenious: But personally would avoid it if possible! As someone said use 120 volt LEDs? At 120 volts that 400 m/a becomes 40 m/a??? Without expense and possible fire risk of transformer/rectifiers which is obviuosly a concern in view of the idea of adding a low amperage fuse/ circuit breaker for your transformer input? BTW even 100m/a (tenth of an amp at 120 volts = 12 watts) even left on all night for say 8 hours = 96 watt hours or approximately one tenth of a kilowatt hour, energy consumption costing at typical North American electricity rates rates something of the order of one cent or less per night per night. For \$3.65 per year? Hardly seems worth the effort of installing more apparatus etc.? If the transformer etc. costs say \$50 the pay back (assuming lights are left on all night?) in lower energy consumption will take something of the order of 5-8 years? If only occasionally the payabck will probably be 'never'.
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For \$3.65 per year? Hardly seems worth the effort of installing more apparatus etc.? If the transformer etc. costs say \$50 the pay back (assuming lights are left on all night?) in lower energy consumption will take something of the order of 5-8 years? If only occasionally the payabck will probably be 'never'.
Stairwell lights are not about money.
Considering that he has four, it may be a rental units. If a stairwell light goes out, it is a code violation. It does not matter if it is an absentee landlord and no one reports the light out, he still gets a fine. There is also the time and trouble to change bulbs in stairwells. It may be very difficult to reach. Payback can be the cost of one light out.
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Ah; more information. Maybe one of the posts is missing in the thread I have been reading? Was not aware it was rental units and the difficulty of reaching the light fixtures.!
Certainly would agree that in the case of landlord tenant relationship reliable lighting could be important.
But even so; the use of low voltage transformer/rectifier and modifying standard wiring for low voltage use sounds like it might not conform and could perhaps confuse an electrician or inspector faced with it later on.
Apart from cost the reliability of those low voltage transformers, the extra fuses etc. etc.???? Maybe add an alarm in case something misoperates?
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wrote in message

Ah; more information. Maybe one of the posts is missing in the thread I have been reading? Was not aware it was rental units and the difficulty of reaching the light fixtures.!
Certainly would agree that in the case of landlord tenant relationship reliable lighting could be important.
But even so; the use of low voltage transformer/rectifier and modifying standard wiring for low voltage use sounds like it might not conform and could perhaps confuse an electrician or inspector faced with it later on.
Apart from cost the reliability of those low voltage transformers, the extra fuses etc. etc.???? Maybe add an alarm in case something misoperates?
Its not a rental its my home and I hate changing the flourescent bulbs and starters. I probably have to change them once a year. The ones that are there are old ones from the 70s and look it. Time for an upgrade and I never want to have to change another bulb or starter or ballast transformer again. New lights and the transformer cost me a little less than \$100, about he same as new flourescent lights and fixtures. New fixtures using 120VAC LED lamps will cost me nearly twice that from what I have seen.
Jimmie
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On Sun, 10 Feb 2008 00:43:32 -0500, "Jimmie D"

If you get a listed class 2 supply (a wall wart would easily do 400ma) you should be safe in any fault condition but I agree supplimental protection in the way of a small fuse in the secondary is a whole lot safer way to go. If nothing ese it will save the supply.
You probably don't need protection on the primary side, listed supplies have some kind of protection. The fuse would have to be on the order of a tenth of an amp or less if you did it.
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To actually answer your question which all but one of the blatherskites seem to have not been able to comprehend, YES, there could be code problems. The best thing to do is figure out just how you want to do the installation, and then call your local Code Enforcement Office to see whether it would meet code or not. You don't have to give them name & address; just tell them it's something your'e considering and you want to know if it'd pass codes. Keep a record of the call also.
Forget all the mA figures etc. you see in the posts so far; they're only based on guesses. Check the fixtures for the specific voltages and current each needs. Then go to RS or someplace and find a regulated power supply for that voltage with the full rated current output. You don't want just a wall wart as someone mentioned because if you disconnect one lite to work on it, or it goes bad somehow, the output voltage rises, probably to too high a value, depending, and possibley ruining the remaining light. If you can't figure it out, then you might have to look for someone with the background and experience to assist you; so far it sure doesn't look like it's this group!
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Regards,

Twayne
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I guess I failed to mention the LED lights came with a wall wart rated to supply all 4 of them. I am not crazy about this type of supply. I have given some thought to replacing it with a regulated supply something like a SOLA 12 volt supply. We use these at work and many of them are well over 20 years old. I am thinking powersupply in a metal box, box fastened to my entrance panel with a couple of close nipples and nuts
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funny other than wires breaking off i have never had a wall wort fail........
has anyone?
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Well, I've had them fail but not catastrophically where they emit sparks and flames. Smoke on one occasion, but normally the temp sensor just burns up & the wall wart becomes a sinker. All the others I've seen have been the inoperable type of failure; they just "quit working" because the internal fuses pop as they are designed to do.
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Regards,

Twayne
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On Mon, 11 Feb 2008 03:21:18 -0500, "Jimmie D"

I don't see any real code issues once you get to the low voltage side. The rules are pretty lax but you should still follow good wiring practices. The Sola supply is really overkill for this application but I assume you are getting a used one for free. Protection on the low voltage side is still a good idea. I would use a fuse sized to about 150% of the expected load and you will want to use fairly large wire, just because of the voiltage drop issue with low voltage. Again something like 14ga romex would be overkill but it is a tough wiring method that will put up with the abuse of pulling through walls. Legally the zip lead they sell for landscape lighting is OK at 12 volts.
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Im using the existing 14 guage wiring and switching. I guess that was really the main issue. Yes the 5 amp SOLA is really a lot of overkill. At work we use a lot of them and whenever they go bad they just go to the back of my truck, I mean dumpster. They are usually very easy to fix. I am also anticipating much more low voltage lighting in the house. I figure the 5 amp power supply will handle all of my future needs. I have also considered just using a transformer and a 25 amp bridge rectifier. This would probably be even more reliable tha the SOLA.
I think low voltage distribution panels are not far off from being part of code.
Jimmie
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On Mon, 11 Feb 2008 12:21:20 -0500, "Jimmie D"

The Sola supply has the advantage of being listed. It has been tested to fail in a safe manner (not burst into flames). Low voltage is still part of the code but the requirements are less stringent than regular chapter 3 wiring methods
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snipped-for-privacy@aol.com wrote:

Technically it looks like the power supply should be listed as class 2 or class 3. In any case there is a limit of 5A over current protection for a 12V supply to remain class 2 and use the looser wiring methods.
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bud--

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If it came with a wall wart new, then that wart is designed for the application and shouldn't be any problem, really. Replacement may be a problem if it ever goes out on you, but ... it's probably fine to use. I guess the main thing would be that whatever gets used has UL or CSA approvals/numbers and if it's a digital switching supply, FCC Part 15. Theoretically you shouldn't be able to buy anything that's not rated thus, but ... anything is possible. The other aspect is the the UL/CSA/EU ratings are for the application you have in mind. Modifying it in any way removes the safety assurance (fire/personal) aspects of the markings regardless of what they are. The metal enclosure might be a bit of overkill, and could be real bad it if restricts air flow from a cooling viewpoint. Some supplies must not be encolsed, some can be; it will be part of their specs. I do mount my battery chargers, things like that which might run unattended with a metal place between them and any flammable mounting surface and sometimes an "L" overhead if there are flammables within a few inches of it. Obviously it's located where looks aren't a concern.
Again, the main thing to do is probably check with local code enforcement to see just what your own local codes say specifically. Purchase what you need so you won't have to modify it.
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Regards,

Twayne
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Thanks Twayne, I did check with them today, and they said my installation plan would meet code. They even said the added fuse on the 120vac side was overkill but a good idea as well as the output fuse. The one thing I added later was a low voltage transorb downstream of the 12v side fuse. If it ever conducts the fuse will instantly blow.
Jimmie
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Regards,

PopRivet
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I like the way you think,I have been telling Lighting Designers and Architects for the last two years of what you are trying to do or have already accomplished.
If you ever need High Output LED's in a 12V format and are willing to go through all this work again let me know, I have designed many types of High Output LED Light Engines for a tremendous amount of applications and a current one being made is for the Round Ceiling light. The goal is to use 24 watts of LED lighting to replace 2 18 watt CFL light bulbs.
Good luck, I really enjoyed the read.
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Jimmie D wrote:
Silliness snipped.
Are their any code

Oh, yeah.
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