What is BS 6708 Type 21 Trailing Cable?
BS 6708 Type 21 mining cable represents an advanced variant of galvanized steel pliable wire armoured flexible cables specifically engineered for demanding mining and quarrying applications requiring a dedicated fourth earth conductor. This four-core configuration distinguishes Type 21 from the three-core Type 20, providing enhanced safety features and compliance with electrical regulations that mandate separate protective earth conductors in mining installations.
Key Identification: Type 21 cables feature four unscreened cores (three phase conductors plus one earth conductor) laid up around an elastomeric cradle without contacting each other, protected by galvanized steel pliable armour between inner and outer sheaths. Rated at 640/1100V with a 3kV test voltage, these cables are designed for use in deep mines where explosive gases and dust can accumulate, as well as surface operations supplying excavating, crushing machines and equipment.
