Blasting Caps. Electric blasting caps are used as part of the electric firing system. Electric caps have lead
wires of various lengths, the most common being 12 feet long. To prevent accidental firing, they have a short-
circuiting shunt that must be removed before using the cap. If the cap is without a shunt, the bare ends of the lead
wires must be twisted together to provide the short circuit. Electric blasting caps require a .09-ampere current for
ignition. Misfires can result from mixing electric caps with different characteristics in a series circuit. One type
of cap may fire before the others have enough electrical energy to fire. With the exception of the military M6 cap,
the electrical characteristics of blasting caps vary greatly, even among lots made by the same manufacturer. For
this reason, different types of commercial caps, even different lots of the same type made by the same
manufacturer, should never be included in the same blasting circuit. The military M6 electric blasting cap, an
instantaneous-ignition, Number 12-strength cap, is the standard Army electric blasting cap. It initiates any
standard demolition charge. M6 blasting caps are electrically uniform, so any lot of M6 caps may be mixed with
any other lot of M6 caps in a blasting circuit without fear of misfires resulting from different characteristics. Use
blasting caps according to the following procedures:
After locating a firing position at a safe distance from the ASP, lay the firing wire from the ring main to the
firing position.
Uncoil or unfold the blasting cap lead wires, holding the blasting cap by the wires, approximately one inch
from the cap. Always point the explosive end of the blasting cap away from your body, other personnel, and
Carefully extend the cap lead wires to their maximum length. Straighten them out by hand. Do not throw,
wave, or snap them to loosen the coils or folds.
Place the blasting cap under a sandbag or a similar object to prevent injuries in the event of a premature
detonation.
Remove the shunt from the blasting cap lead wires. The soldier removing the shunt from a blasting cap's lead
wires must ground himself or herself by grasping the bare ends of the firing wire or by touching the bare
ground. This prevents accumulated static electricity from detonating the blasting cap.
Take one lead wire of the blasting cap in one hand and one lead of the firing wire in the other hand. Point the
free ends towards each other and join them with a few twists. Bend the remaining ends up.
Twist these ends together to form a pigtail. Push the pigtail over to lie along one of the wires, and tape the
connection.
Repeat this action with the remaining lead wires. Stagger the two splices and tape them apart to prevent a
short circuit.
Electric Misfires
Electric misfires must be cleared with extreme caution because of the hazards of burning charges and delayed
explosions. If the misfire is dual-primed and above-ground, wait 30 minutes before approaching, because a
burning charge can cause the second cap to detonate the charge. Clear electric misfires according to the following
procedures:
Check the firing wire connection to the blasting machine or other power source terminals to be sure that the
contacts are good.
Make two or three more attempts to fire the circuits.
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MM0170
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