LED Sign Installation

[mdh8274]

We install a lot of channel letter signs that are illuminated with LEDs. Each letter typically has non-metallic sheathed cable, 2 conductors, that connects through a building fascia to a Class I (I think?) power supply; output is 12VDC, 240W or less. Our cost to install would be a lot less if we didn't have to enclose each cable in flexible metal conduit. I have flipped back and forth in the 2008 code book until I'm ready to scream, but I'm not even sure which article or section even applies. Can somebody explain what installation requirements apply here? Do we have to supply a ground wire to each letter?

 

[batch]

I am actually searching for some code references here as well.

Because, 600.7(D) requires a bonding conductor of a minimum size of 14 AWG for signs we still have to bond each letter. Even though we are power limited.

So I am tryin to see if we are good with a multi wire 14AWg cable with out conduit.

 

[batch]

Oh and most of the time in the sign industry we are dealing with class II power supplies and UL restricts the wattage to each circuit to 60 watts. The 240 watt power supply you referenced most likely has four out put or it is illegal.