Tunnels for highways, railways, and hydroelectric dams are often dug by a very large electric-powered piece of equipment called a “ Tunnel Drilling Machine“ - also called a TBM or “mole”. When done in hard rock, this type of tunneling is called Mechanized Rock Excavation (MRE). TBMs and MREs require electrical power, as well as compressed air and water for operation and service. Cables and hoses with very large cross-sections must be managed by special reeling systems designed for this purpose. These reeling machines must keep cables and hoses safe, so as to guarantee a steady flow of energy and data transmission. The reels must operate in very demanding conditions and wet, dusty environments. Current requirements and voltages are very high; the latter can be up to 36 kV. The slip ring assembly in the reel must be built to handle the power.