EFI detonator initiation system and method

In one aspect of the invention, an environmentally insensitive initiator, including: an electro-explosive device responsive to an electrical signal of unique voltage and frequency applied to the electro-explosive device, the unique voltage and frequency being such that are not otherwise present in a well completion operation. An example of voltage and frequency is 350V at 900 Hz. In another aspect, an initiator insertable in a housing insertable in a well casing, the initiator having a contact which is grounded when the initiator is uninstalled, to protect against unintended currents, but which becomes ungrounded by the act of inserting the initiator in the housing. In a further aspect, an initiator including a dual-function fuse. In the first function, the fuse permits a prefire, low-current, continuity test through electrical circuitry without applying electrical energy to the initiating element, but an internal element of the fuse will open if an unintended higher current, above a threshold, is applied to the fuse. In the second function, the fuse is destroyed as a result of the detonator charge being detonated, permitting a post fire test to verify detonation of the detonator charge by sensing the destruction of the fuse. In an additional aspect, a circuit card assembly protected against physical damage.\!