A pair of insulated copper conductors which lead from the exploder to the detonator wires. It may be either twin-core (both conductors contained in the one cable) or singlecore (each conductor contained in a separate cable). Twin-core cables having cores of four strands, each 0.018 in (0.046 cm) in diameter (4/0.018) with a resistance of approx. 5 Omega per 100 yd (91 m), are commonly used. Actual choice of cable must depend upon conditions of use and the relevant regulations.