PRELIMINARY ELECTRICAL TESTING

TM 9-1300-277

firing system will not be conducted during sand, dust, or

d. Electric blasting caps of different manufacture

snow storms. Under such conditions, all electrical

or type will not be used in the same system.

operations will be suspended, cap and lead wires

shunted, and personnel removed from the disposal area.

e. When uncoiling the leads of blasting caps, the

cap will not be held directly in the hand, but will be held

5-8.

PRELIMINARY

ELECTRICAL

CONTINUITY

by the wires approximately 2.5 centimeters (1 inch) from

TESTING

the cap. The lead wires will be straightened out by hand

and not thrown, waved, or snapped to loosen coils.

The galvanometer, blasting caps and firing

wires will be tested prior to the disposal operation in

f. Individuals connecting/testing electric blasting

accordance with the following paragraphs.

caps will make use of available protective cover when

completing the circuit.

The distance between the

WARNING

individual and the blasting cap will be the maximum

PRIOR TO USING GALVANOMETER,

permitted by length of cap leads. The individual will

ENSURE

THAT

ONLY

THE

keep his back toward the blasting cap when making the

APPROPRIATE SILVER CHLORIDE

connection.

DRY CELL BATTERY IS INSTALLED.

ANY

OTHER

BATTERY

MAY

g. Blasting caps will be tested for continuity with a

PRODUCE SUFFICIENT VOLTAGE

galvanometer or .'51 test set prior to connecting to firing

TO DETONATE BLASTING CAPS.

circuit. The shunt will not be removed from the lead

wires of the blasting cap until the moment of testing.

a. Galvanometer. The galvanometer (fig. 5-8) will

be tested prior to use by holding a piece of metal across

h. The individual removing the shunt will ground

its two terminals. If this does not cause a wide

himself to prevent accumulated static electricity from

deflection of the needle (29 to 25 units), the battery is

firing the blasting cap by grasping the firing wire.

weak and will be replaced. When used in a cold

Immediately after testing, the lead wires will be shunted

climate, the galvanometer will be protected from

by twisting the bare ends of the wires together. The

freezing by keeping it under clothing and near the body.

wires will remain shunted until connection into the firing

circuit.

b. Blasting Caps.

i. Both ends of the firing wires will be shunted

(1) Each blasting cap to be used in the

except when firing the charge or testing the circuit. The

electric firing system will be individually tested.

connection between blasting caps and the circuit firing

wires will not be made unless the power end of the firing

WARNING

wires is shunted and grounded.

ALWAYS POINT THE EXPLOSIVE

END OF BLASTING CAP AWAY

j. Firing wires will be secured near the point where

FROM THE BODY, OTHER PERSON-

the blasting cap(s) are connected.

NEL, AND EXPLOSIVES.

k. Prior to making connections to the blasting

INDIVIDUALS WILL MAKE USE CF

machine, the firing circuit will be tested with a

AVAILABLE PROTECTIVE COVER

galvanometer or M51 test set for electrical continuity.

AND KEEP THEIR BACKS TOWARD

THE BLASTING CAP WHEN TESTING

l. The blasting machine or its activating device will

CAPS FOR CONTINUITY WITH A

not be surrendered to the individual designated to fire

GALVANOMETER. THE DISTANCE

the charge until the supervisor is assured that the area

BETWEEN

INDIVIDUALS

AND

is cleared of personnel, equipment, etc.

BLASTING CAP WILL BE THE

MAXIMUM PERMITTED BY LENGTH

m. Disposal operations will not be conducted during

OF CAP LEADS.

an electrical storm or when such a storm is approaching.

Additionally, disposal by detonation using an electrical

Change 1

5-7