A network transformer for providing power to a secondary network comprising: a ferromagnetic core comprising at least one limb (41, 42) extending between first and second yokes (44, 46); at least one coil assembly mounted to the at least one limb (41, 42); a hermetically-sealed enclosure having an interior space within which said ferromagnetic core and said coil assembly are disposed, said hermetically-sealed enclosure having a connective throat extending from a wall of said hermetically-sealed enclosure; a combustion-inhibiting gas disposed within said interior space of said hermetically-sealed enclosure, said combustion-inhibiting gas surrounding said ferromagnetic core and said at least one coil assembly; and a network protector removeably mounted to said connective throat of said hermetically-sealed enclosure, said network protector being operable to protect said network transformer from power flowing from said secondary network, and characterised in that said hermetically-sealed enclosure comprises: at least two hooks disposed proximate to and extending from a side edge of a top lid of said hermetically-sealed enclosure, the at least two hooks being adapted to engage with a beam proximate to a ceiling of a vault; and a bracket having a key-hole shaped opening rigidly attached to and extending from a side wall of said hermetically-sealed enclosure, said bracket being adapted to engage with a key-hole shaped tab rigidly attached to an inside side wall of said vault. a ferromagnetic core comprising at least one limb (41, 42) extending between first and second yokes (44, 46); at least one coil assembly mounted to the at least one limb (41, 42); a hermetically-sealed enclosure having an interior space within which said ferromagnetic core and said coil assembly are disposed, said hermetically-sealed enclosure having a connective throat extending from a wall of said hermetically-sealed enclosure; a combustion-inhibiting gas disposed within said interior space of said hermetically-sealed enclosure, said combustion-inhibiting gas surrounding said ferromagnetic core and said at least one coil assembly; and a network protector removeably mounted to said connective throat of said hermetically-sealed enclosure, said network protector being operable to protect said network transformer from power flowing from said secondary network, and characterised in that said hermetically-sealed enclosure comprises: at least two hooks disposed proximate to and extending from a side edge of a top lid of said hermetically-sealed enclosure, the at least two hooks being adapted to engage with a beam proximate to a ceiling of a vault; and a bracket having a key-hole shaped opening rigidly attached to and extending from a side wall of said hermetically-sealed enclosure, said bracket being adapted to engage with a key-hole shaped tab rigidly attached to an inside side wall of said vault. at least two hooks disposed proximate to and extending from a side edge of a top lid of said hermetically-sealed enclosure, the at least two hooks being adapted to engage with a beam proximate to a ceiling of a vault; and a bracket having a key-hole shaped opening rigidly attached to and extending from a side wall of said hermetically-sealed enclosure, said bracket being adapted to engage with a key-hole shaped tab rigidly attached to an inside side wall of said vault.