burial depth for landscape wires

[GerryB]

For some reason I thought I read on this site that the landscape lighting cable technically should be 18". I can't find it now and table 300.5 says 6". I told the contractor it was a grey area and should be 18", but if the wires wind up there I will install the lights. I told him to get 10-2 low voltage cable, which he did. So 6" is correct?

 

[infinity]

Column 5 in T300.5 says 6" if using UF or another identified type of cable and not more than 30 volts.