Intermountain (also called Path 27) is the designation of a bipolar HVDC transmission line between the Intermountain power plant in Utah and the Adelanto static inverter plant near Adelanto, California. The Intermountain is a bipolar overhead line with a length of 785 km can transfer a maximum power of 1,920 megawatts at ±500 kV. The part of the line that travels through the Mojave Desert is followed by many other AC 500 kV lines and Interstate 15. The Pacific DC Intertie is the other HVDC line serving Los Angeles. This HVDC line is owned and operated by the Los Angeles Department of Water and Power (LADW&P). HVDC lines such as the Intermountain line and the Pacific DC Intertie can be distinguished by the observer by having two transmission lines, rather than the three necessary for transmission of three-phase AC power.
From the south, the Intermountain DC wire starts at the Adelanto substation and static inverter plant. The line heads east for a short distance, until two 500 kV wires and one 287 kV wire (both LADW&P Path 46
wires) meet up with the DC line from the Victorville substation, which the DC line bypasses. Heading together, the four lines head generally northeast, paralleling Interstate 15
and spanning over the highway at two places. An additional line, called Path 64
, but part of Path 46
, parallels the Interstate 15 and the four lines until the California-Nevada border. The DC line splits and runs farther away from the other three 500 kV lines and the 287 kV line until the three 500 kV lines terminate at the Eldorado, Marketplace and the McCullough substations. As for the DC line, the line heads in a more northerly direction as it traverses through southeastern Nevada and the Las Vegas
region with another 500 kV line from McCullough substation. The same 500 kV line spans across Interstate 15 with the DC line and the 500 kV line passes through Crystal substation, while the DC line bypasses another substation yet again. From Nevada on north into Utah, the DC line generally parallels the 500 kV wire and Interstate 15. The DC line turns gradually to head north-northeast as it gradually separates from Interstate 15. As for the 500 kV (Path 21
) line, the line turns and heads east, spanning over the Colorado River
. The DC line continues to head north-northeast out of sight of Interstate 15 as the line crosses high mountains and large desert basins until it turns east in west-central Utah and terminates at the Intermountain substation.