Handmade driver

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darekelec

Senior Member
Location
nyc
Hi, guys. What do you think of using magnetic low voltage transformer 120/12 V with a rectifier to run 12V DC LEDs. my company has been installing them for a while now with great results.
 

iwire

Moderator
Staff member
Location
Massachusetts
Hi, guys. What do you think of using magnetic low voltage transformer 120/12 V with a rectifier to run 12V DC LEDs. my company has been installing them for a while now with great results.

I think it is an NEC violtion.

Article 411 requires the components to be listed.
 
Location
NE (9.06 miles @5.9 Degrees from Winged Horses)
Occupation
EC - retired
Hi, guys. What do you think of using magnetic low voltage transformer 120/12 V with a rectifier to run 12V DC LEDs. my company has been installing them for a while now with great results.

We make quite a few gadgets that work in the shop. They never see the light of day. One was a BB gun mouse control device triggered by a proximity sensor. It did work although it emptied the magazine before you could blink. Minor detail. It worked. What else should be required ?
 

kwired

Electron manager
Location
NE Nebraska
I think it is an NEC violtion.

Article 411 requires the components to be listed.
More importantly they need to be listed to be used together...

I would ask my insurance rep what they think about using, selling and installing an unlisted shop built device.
We assemble things all the time that are listed, but the end result is not an individual listed item.

A home, business, industrial plant is not a listed item, it is built out of many listed components, and some that are not listed.
 
Location
NE (9.06 miles @5.9 Degrees from Winged Horses)
Occupation
EC - retired
More importantly they need to be listed to be used together...

We assemble things all the time that are listed, but the end result is not an individual listed item.

A home, business, industrial plant is not a listed item, it is built out of many listed components, and some that are not listed.

We all do it or have. Our inspectors have taken the attitude that we do not create industrial control panels by custom building an assembly of items that have some sort of listing individually. As I understand it, if I started making cabinet after cabinet as a Pivot Mfg does, they would take an entirely different viewpoint.

Why I think making my own power supply for LEDs is different, I don't know.
 

iceworm

Curmudgeon still using printed IEEE Color Books
Location
North of the 65 parallel
Occupation
EE (Field - as little design as possible)
We all do it or have. Our inspectors have taken the attitude that we do not create industrial control panels by custom building an assembly of items that have some sort of listing individually. As I understand it, if I started making cabinet after cabinet as a Pivot Mfg does, they would take an entirely different viewpoint.

Why I think making my own power supply for LEDs is different, I don't know.

Take a look at NEC 409. I think it says you can do just about what you have suggested (bolded)

ice
 

__dan

Senior Member
Hi, guys. What do you think of using magnetic low voltage transformer 120/12 V with a rectifier to run 12V DC LEDs. my company has been installing them for a while now with great results.

???

The LED driver is usually a constant current, current limited, source. So, a 12 V driver would have x number of LEDs in series at a constant current suitable for the lamps or target lamp string output.

What you described is a rectified constant voltage source, not current regulated, leading me to think the LED module you're installing has its own current regulation device (built in led driver). ??? What you described, overvoltage with no current limiting, would be misapplied straight into a bare led.

Have you looked at the Meanwell led drivers? They're very low cost.

http://distributor.meanwellusa.com/webnet_usa/search/seriessearch.html
 

darekelec

Senior Member
Location
nyc
It's not me. my boss wants electricians to install magnetic transformers with rectifiers from radioshack. to make it more weird those installations go to multi million hi end residences. inspectors overlook low voltage installations here and this combination works every time. on my job i connected this invention with led strips ;
http://www.jescolighting.com/web/catalog.aspx
and it looks good

recently i had in my hand similar device from reputable manufacturer
http://technomagnet.com/dc-output-magnetic-75w-12v-led-transformer-driver.html
 

darekelec

Senior Member
Location
nyc
Is the transformer a listed class 2 transformer? is it a class 2 circuit?

I guess my circuits for the led strips I would call class 1 power limited because from 200W xfmr (protected on primary) with rectifiers added i go to leds with AC cable although it clearly says on led strips 'connect to class 2 circuit 24V 100VA max. it's not my design. low voltage installations in NYC resemble those from middle ages :happyno:
 

kwired

Electron manager
Location
NE Nebraska
The following is from 411.3. The low voltage system needs to be either listed as a complete system or made from components listed as part of the same identified system.

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.

 

__dan

Senior Member
OK, now what you're describing is not the driver, it's the class 2 power supply to the LED fixture that has the driver built in.

http://www.jescolighting.com/web/catalog.aspx?product=3045

The specs list the input voltage, for the above, as 24 VDC. Has to be a listed class 2 supply. There is still a difference between your rectified AC (class 2) transformer and a factory built 24 VDC power supply, some better filtering and voltage regulation possibly. This may or may not make a difference to the LED driver inside the fixture. The results of any difference would be operating efficiency, heating at the LED driver, and lamp / driver lifetime. Some further inquiry, testing, is indicated.

Yes, it works. I would not ignore the question of, how well does it work. The transformer should also say "listed class 2" and then it remains to do it by the numbers for load rating and voltage.
 

John120/240

Senior Member
Location
Olathe, Kansas
Hi, guys. What do you think of using magnetic low voltage transformer 120/12 V with a rectifier to run 12V DC LEDs. my company has been installing them for a while now with great results.

It's not me. my boss wants electricians to install magnetic transformers with rectifiers from radioshack. to make it more weird those installations go to multi million hi end residences. inspectors overlook low voltage installations here and this combination works every time. on my job i connected this invention with led strips ;
http://www.jescolighting.com/web/catalog.aspx
and it looks good

recently i had in my hand similar device from reputable manufacturer
http://technomagnet.com/dc-output-magnetic-75w-12v-led-transformer-driver.html

You state.."multi million hi end residences." What is the motivation to go cheap on a job like this ? In my experience million dollar home owners don't want some cobbled together installation. Why try to reinvent the wheel ?

When hockey puck lighting was the IN thing they always came as a package deal. Why would LED's be any different ?
 
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