Radiated radio-frequency hazards with electric detonators: Influence of wiring configuration, dipole vs V-antenna

The safety of personnel is of a major concern when using and manipulating hotwire electric detonators. A lot of publications exist regarding the influence of electric fields on electric detonators. Most of them give safety distances in function of the E.I.R.P. (Equivalent Isotropic Radiated Power) taking into account several hypotheses, like the maximum electric fieldstrength in the presence of which the detonator is safe, related to the MNFS (Maximum No-Fire Stimulus) and the dipole configuration of the electric detonator wiring. To our knowledge all the standards and guides, military and civil, published up to now take as the worst case for wiring the dipole configuration (with the exception of loop and other antennas without further details). The present paper establishes that the worst case is rather when the wiring is arranged as a V-antenna with an aperture angle between the detonator wires of about 20°. When the angle is close to about 20° the current in the hotwire is higher than in the dipole configuration and reduce the safety margin of demining personnel.