Figure 5-20. Electrical tape splicing.
5-19. DUAL ELECTRIC FIRING SYSTEM
5-18. DUAL NONELECTRIC FIRING SYSTEM
This consists of two independent nonelectric
This consists of two independent electric
systems for firing a single charge or set of charges.
circuits, each with an electric blasting cap in each
Figure 5-22 shows the layout for nonelectric dual firing
charge, so that the firing of either circuit will detonate all
system for a single charge. If two or more charges are
charges (fig. 5-24).
to be fired simultaneously, two detonating cord ring
mains (fig. 5-23) are laid out, and a branch line from
5-20. COMBINATION DUAL FIRING SYSTEM
each charge is tied into each ring main. Additional
reliability can be obtained from dualdetonating cord-
The combination dual firing system uses an
primed firing systems by extending the cap ends of the
electric and nonelectric firing system (fig. 5-25). Each
lead-in detonating cords, as shown in figure 5-23, and
charge is primed electrically and nonelectrically. Both
tying them together in a square knot (girth hitch with one
the electric and nonelectric systems must be entirely
extra turn), or by connecting the cord with detonating
independent of each other. The nonelectric system
must be fired first.