Introduction 

One significant change to UL 44 (Standard for Safety for Thermoset-Insulated Wires and Cable) in the 2018 release is the addition of the 1000 Volt rating of US type designations. Now XHHW, in addition to having a 600 Volt rating, can be rated 1000 Volt. RHH and RHW cables, which had 600 V and 2000 V ratings, now can be rated 1000 Volts.