970

LAWS OF MARYLAND

[Ch. 4

RULE 5-10 PREVENT A BLOW-THROUGH, EACH
PORTION OF THE BOREHOLE WHERE THE
HEIGHT OF THE COAL PERMITS SHALL HAVE
A BURDEN IN EVERY DIRECTION OF AT
LEAST 18 INCHES BEFORE BEING FIRED.

POLE 6 - EACH BOREHOLE SHALL BE STEMMED
WITH AT LEAST 24 INCHES OF
INCOMBUSTIBLE MATERIAL, OR AT LEAST
ONE HALF OF THE LENGTH OF THE HOLE
SHALL BE STEMMED IF THE HOLE IS LESS
THAN FOUR FEET IN DEPTH.

PULE 7 - IN A GASSY MINE, AN EXAMINATION

FOR GAS SHALL BE MADE IMMEDIATELY

BEFORE AND AFTER FIRING EACH SHOT

WHERE ONSHIFT SHOOTING IS DONE.

(2)     CHARGES BETWEEN ONE AND ONE-HALF
POUNDS AND THREE POUNDS.—CHARGES EXCEEDING ONE AND
ONE-HALF POUNDS, BUT NOT EXCEEDING THREE POUNDS, SHALL
BE USED ONLY IF THE BOREHOLE IS SIX FEET OR MORE IN
DEPTH; THE EXPLOSIVE IS CHARGED IN A CONTINUOUS TRAIN,
WITH NO CARTRIDGES DELIBERATELY DEFORMED OR CRUSHED,
WITH ALL CARTRIDGES IN CONTACT WITH EACH OTHER, AND
WITH THE END CARTRIDGES TOUCHING THE BACK OF THE HOLE
AND THE STEMMING RESPECTIVELY; AND CLASS A OR CLASS B
PERMISSIBLE EXPLOSIVES ARE USED. THE THREE POUND
LIMIT DOES NOT APPLY TO SOLID ROCK WORK SUCH AS SOLID
ROCK TUNNELS.

(3)    FIRING SHOTS.—A SHOT MAY BE FIRED BY
ANY CERTIFIED SHOT FIRER IN A MINE USING COAL-CUTTING
EQUIPMENT. THE SHOT FIRER SHALL COMPLY WITH THE
REQUIREMENTS OF THIS SUBTITLE PERTAINING TO BLASTING.
IN ANY MINE WHERE CHARGING OR SHOOTING IS DONE ON
SHIFT, EACH SHOT OR GROUP OF SIMULTANEOUS SHOTS SHALL
BE FIRED IMMEDIATELY AFTER IT IS CHARGED.

(4)    TAMPING BARS; LEG WIRES; FIRING FROM
CIRCUIT.-—ONLY WOODEN TAMPING BARS SHALL BE USED TO
CHARGE A HOLE. LEG WIRES OF ELECTRIC DETONATORS SHALL
BE KEPT SHUNTED OR THE ENDS TWISTED TOGETHER UNTIL
READY TO CONNECT TO THE FIRING CABLE. NO SHOT MAY BE
FIRED FROM THE POWER OR SIGNAL CIRCUIT WHILE WORKERS
ARE IN THE MINE.

(5)    TESTING ROOF AND FACES.—ROOF AND
FACES OF WORKING PLACES SHALL BE TESTED BEFORE AND
AFTER BLASTING.