1) underground cable
2) buried cable
3) subterranean cable
4) cable line
5) underground line
an electric line with insulated conductors buried directly in the ground, or laid in cable ducts, pipes, troughs, etc.
GRM: n. (1,2,3,4,5)
USG: expression used to describe the item physically
References:
GEN electric line
SEE underground network
SEE underground system

ENERGY TERM COURTESY OF ENERGY.EU