Normally Aluminum quadruplex is used for 3 phase and 220 volt. URD can be put into ducts or directly buried. It is composed of 1350-H19 Aluminum conductors, crosslinked polyethylene insulation XLPE. Insulated conductors have print on them indicating the gauge and insulation and type. The neutral is painted yellow or orange or another bright color to indicate the differentiation from the phase conductors.

Sometimes Quad URD is manufactured in duct but not normally. Depending on your environment you can put it in conduit if you’re worried about ground movements and rodents getting into the materials. Although there is a prevailing fear of splicing underground it’s normally not that big of a deal and splices done by electricans are usually pretty reliable. The insulation is USE-2 and XLPE with a conductor of Compact stranded 8000 series aluminum alloy. Aluminum URD is replacing the Copper VNTC simply due to cost effective. Will aluminum corrode? The reality is that as long as the wire is properly installed the longevity is very close to that of copper’s longevity.