Figure 5-16. Square knot connections

TM 9-1300-277

cords; otherwise, the cords will cut each other and

destroy the firing system.

Figure 5-16. Square knot connections.

Figure 5-17. Girth hitch with one extra turn.

a. Branch Line Connections. A branch line is

fastened to a main line by means of a clip (fig. 5-15) or

a girth hitch with one extra turn (fig. 5-17). The branch

line is clipped with the U-shaped trough of the clip and

the main line with the tongue of the clip. The clip is bent

against the cord, holding the connection securely. The

angle formed by the branch line and the cap end of the

main line should not be less than 900 from the direction

from which the blast is coming; at a smaller angle, the

branch line may be blown off the main line without being

detonated. At least 15 centimeters (6 inches) of the

running end of the branch line is left free beyond the tie.

The running end of the girth hitch will be on the opposite

side of branch line from initiating point on the main.

b. Ring Main. A ring main is made by bringing the

main line back in the form of a loop and attaching it to

itself with a girth hitch with one extra turn (fig. 5-18).

This will detonate an almost unlimited number of

charges. The ring main makes the detonation of all

Figure 5-18. Ring main with branch lines.

charges more positive because the detonating wave

approaches the branch lines from both directions and

c. Initiating Cap. The detonating cord main line is

the charges will be detonated even when there is a

initiated by an electric blasting cap when an electric

break in the ring main. Branch line connections should

firing system is being used, or by a nonelectric blasting

be made perpendicular to the ring main. Any number of

cap when a nonelectric firing system is being used. The

branch lines may be connected to the ring main, but a

blasting cap is firmly attached at least

branch line is never connected at a point where the ring

main is spliced. In making detonating cord branch line

connections, avoid crossing lines. However, if this is

necessary, be sure to have at least 0.30 meters (one

foot) of clearance at all points between the detonating

Change 2

5-14