UL 508 power supply used for LED exterior building lighting

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jmartin

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A fixture manufacturer is asking me to specify a power supply separate from the light fixture.

The 24 volt DC unit is listed under UL 508.

Is this gear allowed for building lighting alternate use?

I cannot cite the code but I believe there is a limit of 4 amps at 24 volts and 5 amps at 12 volts when using DC secondary voltage to feed light fixtures.

Can anyone can direct me to the correct code or comment on this?

There seems to be a great deal of bad information on the street for these systems.
 
The 4A / 24V issue comes from the concept of a "Class 2 transformer" as used in "Limited Energy" systems. A Class 2 transformer is one where the total power output is 100VA or less. So if you have 24VDC, that is 4A. By the way, if you have 12VDC, that would be 8A, not 5. Not sure where that was coming from, 5A would be 20V but I have never seen a 20V power supply. So back to your issue, if you have to use a Class 2 transformer or power supply, you will be up against the 100VA limitation.

http://ulstandardsinfonet.ul.com/outscope/outscope.asp?fn=0879A.html
 
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