Abstract: Disclosed is an electronic detonator delay assembly, having an associated detonator, that can be pre-programmed on site with a time delay and installed in a borehole to carryout a blast operation. The assembly is first coupled to a programming unit to program the desired time delay, and then to a blasting unit, by means of a magnetic coupling device in the electronic delay assembly and to a single pass of a conductive wire through the magnetic coupling device. The programmed time delay in the electronic delay assembly can be double checked through a wireless communication link between the electronic delay assembly and the programming unit.