Aluminum UD (Underground Distribution) Triplex is approved for direct burial or installed in ducting underground. The three phase conductors are insulated with black XLP (Crosslinked Polyethylene). One conductor is phase identified with a yellow stripe. These cables are rated 600 Volts 90C in installed per the National Electric Code to provide power to residential & commercial buildings. Please be sure to consult with an engineer or licensed electrician to properly size the cable required.