An old discussion on radio frequency (RF) hazards on Linked In’s Blasting Professionals group resurfaced recently. Several participants have asked ERM for RF incident reports from our files, which we gladly provided.
We understand completely the desire for documentation, but it strikes us that some people may doubt whether or not an electric detonator can be initiated with RF. Uhh, let’s see here…every wireless device created by man converts radio wave energy into electricity and we’re wondering what again?
Truth be told, it is difficult to initiate standard electric detonators with RF. One must cause over 50 milliamps of current to flow through the bridgewire for even a remote possibility. If currents capable of reliably initiating electric detonators were being picked up by the wires, then people would also be getting shocked. And people do get shocked by metal objects that gather charge in an RF field. Electric detonators have been initiated with standard RF sources many times in laboratory conditions so there should be no doubt.
The Institute of Makers of Explosives’ SLP-20 provides safe distances around various broadcast transmitters and should be the first reference. SLP-20 only applies to electroexplosive devices with a 40-milliwatt or more no-fire level and 50-ohm resistorized detonators. If more sensitive detonators are used or if the distances specified in SLP-20 are too restrictive, expert technical assistance should be sought.