transformer/driver for 12v LED?

rodvprt

Member
Location
oakland ca
I'm installing some LED strip lights for an indirect lighting system. They are driven at 12V, in parallel, with a total load of about 60W (about 50' of lights). I would prefer to use a concealable transformer, and hide it behind an access panel. I don't need to be able to dim them. I have found some drivers that claim to be specifically for LED applications, but am wondering if I can use a transformer for a 12V track lighting system? I suppose it depends on how the rectification is done in the transformer, but most manufacturers don't list it, and few also list the efficiency of the unit. Any recommendations on the subject, or pointers to suppliers of drivers? thanks, Roy.
 

Dennis Alwon

Moderator
Staff member
Location
Chapel Hill, NC
Occupation
Electrical Contractor
First you will need to call the manufacturer as it will depend on the lights. Not all transformers are created equal and there may be drivers needed that many transformers won't have. Also concealing low voltage wiring behind walls and cabinets may not be compliant at all. Art. 411 is the appropriate code for that.
 

pete m.

Senior Member
Location
Ohio
I know this has nothing to do with the answer to your question but it is a consideration (which you may have already made).

411.3 Listing Required. Lighting systems operating at
30 volts or less shall comply with 411.3(A) or 411.3(B).
(A) Listed System. Lighting systems operating at 30 volts
or less shall be listed as a complete system. The luminaires,
power supply, and luminaire fittings (including the exposed
bare conductors) of an exposed bare conductor lighting system
shall be listed for the use as part of the same identified
lighting system.
(B) Assembly of Listed Parts. A lighting system assembled
from the following listed parts shall be permitted:
(1) Low-voltage luminaires
(2) Low-voltage luminaire power supply
(3) Class 2 power supply
(4) Low-voltage luminaire fittings
(5) Cord (secondary circuit) for which the luminaires and
power supply are listed for use
(6) Cable, conductors in conduit, or other fixed wiring
method for the secondary circuit

The luminaires, power supply, and luminaire fittings
(including the exposed bare conductors) of an exposed bare
conductor lighting system shall be listed for use as part of
the same identified lighting system.

Pete
 

rodvprt

Member
Location
oakland ca
Unfortunately, the manufacturer of these strip lights does not provide a driver. They're very simple - groups of 3 LEDs and a small resistor in series, wired in parallel on a flexible strip with a density of one group per 5 cm, in reels 5m long. Power consumption is a little less than a Watt / foot. There is no temperature regulation or control electronics, so it basically just wants pure 12V DC. I have seen that a lot of drivers for low voltage track systems are designed for incandescant applications, and really just have a rectified high frequency A/C waveform, which would probably cause this sort of a setup to flicker. I have seen some drivers made by Hatch and various no-name Chinese manufacturers which claim to provide a constant voltage D/C signal, but am hoping others have encountered this situation before and have a good solution.
 

1793

Senior Member
I'm installing some LED strip lights for an indirect lighting system. They are driven at 12V, in parallel, with a total load of about 60W (about 50' of lights). I would prefer to use a concealable transformer, and hide it behind an access panel. I don't need to be able to dim them. I have found some drivers that claim to be specifically for LED applications, but am wondering if I can use a transformer for a 12V track lighting system? I suppose it depends on how the rectification is done in the transformer, but most manufacturers don't list it, and few also list the efficiency of the unit. Any recommendations on the subject, or pointers to suppliers of drivers? thanks, Roy.
How does the "tape" connect to the driver?
How are the sections of "tape" connected together?

I think WAC has a driver, don't have it with me right now, that lists 1w min. and 60W max. I can look at it in the morning and post it tomorrow.
 

Dennis Alwon

Moderator
Staff member
Location
Chapel Hill, NC
Occupation
Electrical Contractor
I would still contact the manufacturer and ask what transformer is to be used. Some transformers may work directly with the lights. If they don't know then they shouldn't be making the darn things.
 

rodvprt

Member
Location
oakland ca
the tape looks like a flexible printed circuit board, about 8mm wide. It's made in sections about 50cm long, that are soldered together, with is a self adhesive backing on the underside. It can be cut at the end of every 3 LED group. At the ends, the tape has size M coax connectors, so they can can be joined in series (though I would worry about resistive losses over very long runs), or connected to a power supply.
 

Sierrasparky

Senior Member
Location
USA
Occupation
Electrician ,contractor
THere are a couple of LED shops on the inernet that sell a drivers of different wattage specifically for LED strips like you describe. THey are made to fit in a J-box.

I would not use a transformer from a LV track system as it might not be DC and most LED's I belive need to have full wave DC.
 

AVD001

Member
I use GM lighting for my LED ribbon needs. I always get a dimmable driver because the home owners 95% of the want to be able to dim the lights. If you don't get a dimmable driver you'll have to get a LV dimmer on the load side. They don't look nice in my opinion.
 

steve66

Senior Member
the tape looks like a flexible printed circuit board, about 8mm wide. It's made in sections about 50cm long, that are soldered together, with is a self adhesive backing on the underside. It can be cut at the end of every 3 LED group. At the ends, the tape has size M coax connectors, so they can can be joined in series (though I would worry about resistive losses over very long runs), or connected to a power supply.
That sounds like its exactly the opposite of what's required by the article Pete posted.

It seems like those are just electronic components that a maunfacturer could use to make a light fixture. It doesn't sound like they are a complete listed assembly.

If that's the case, in most areas I don't think that would fly, at least as a permenant installation.

Sorry, I know that's not the help you are looking for, but this is a forum dedicated to the National Electric Code.
 

1793

Senior Member
This is the driver I have, waiting for install. This one has a manufactured 6' load side power lead. There are other transformers/drivers available from WAC as well.

IMG_2062-2.jpg
 

rodvprt

Member
Location
oakland ca
I'm very interested to see how that WAC driver works out for you - I saw that one on their web site, and noticed that it's output is 12V at 20kHz (note that the it's printed as 12V AC 5A on the bottom of the driver shown above), and I wasn't sure if that was going to cause the LEDs to flicker or not.. The LED strips I have can be found at Amazon at: http://www.amazon.com/gp/product/B002QQ48T or from Diode LEd at: http://www.diodeled.com/products-view.php?id=67 however, there are many sellers of very similar strips. Note that it has only 2 connectors, unlike the 4 connector ones from WAC
 
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