voltage limit for "low voltage" landscape lighting

[RustyShackleford]

Very simple question, which I should know ... but do not, never having worked on voltages higher than 12v and lower that 110-120vac.

How high a voltage is acceptable for "low voltage" lighting, landscape lighting in particular ?

 

[RustyShackleford]

Article 411 suggests the limit is 30v (or 42v "peak", presumably meaning 30 RMS AC is ok).

Landscape lighting is clearly a "wet area".

For this project, I'm interested in ripple-free DC only.

 

[RustyShackleford]

It looks like the UL could be an issue, effectively requiring a 15v limit:

http://ecmweb.com/content/code-rules-low-voltage-lighting

 

[RustyShackleford]

No one seems to care, but FWIW ...

I actually emailed a UL guy, and he got back to me, telling me that (for wet locations) 30v is the limit for "pure DC", which seems to be defined as the peak-to-peak ripple being less than 10% of the DC voltage. The max for sinusoidal AC is 15v.

He says this is in UL1838 (see below), and also in a note to Table 11B of the NEC (presumably not the 2011 version, which is where I was looking).