Cherie Berry, Commissioner of Labor
1-800-625-2267 ♦ www.nclabor.com
Occupational Safety and Health Division
HOI Mail Service Center, Raleigh, NC 27699- 1
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Blasting: The Dangers of Type 1.4S Explosives
Blasting and Use of Explosives Standards Apply to Type 1.4S Explosive Devices and Cartridges
An explosion occurred during the construction of a parking deck
while an employee was using a type l .4S explosive cartridge device
working at the bottom of a 1 9-foot shaft. The employee was setting the
cartridges to blast rock. To use the firing device and cartridges, a worker
drills into the rock, places one or more cartridges in the hole, and sets the
firing device. The worker then exits the area and sets off the explosive
from a safe distance. In this instance, a cartridge failed to fire. The
employee re-entered the shaft and attempted to drill a parallel hole in
which to put another explosive cartridge. The drill accidently entered
the original hole and set off the explosive that was still there, causing
serious injury to the driller.
Tools growing in popularity that are generally referred to as “rock¬
breaking tools” are actually explosives. These tools are sold under many
brand names, including Magnum Buster, Pyroblast-C, GasBlaster and
AutoStem. These explosives deflagrate rather than detonate, which does
make them less hazardous. The risk of injury is not eliminated. These
tools are sold in many different sizes and by different manufacturers.
This type of cartridge is classified as a type l.4S explosive by the U.S.
Department ofTransportation. This category is also defined as an explosive
under the NC'DOL blasting standards. Use and handling of these explosives
require care and compliance with applicable standards, Title 13 of N.C.
Administrative Code, 07F .0700, Blasting and Use of Explosives.
The type l ,4S cartridge holder alone is not classified as an explosive.
It contaias no explosive in the same way that a firearm when empty of
bullets contains no gunpowder. The type l ,4S explosive cartridges fired
during use of a completed end-use device and firing assembly mix (firing
device and cartridges) are explosives, and using type l ,4S explosive
What is a type 1.4S explosive?
Class l Explosives — Division l. 4 consists of explosives that
present a minor explosion hazard. The explosive effects are largely
confined to the package and no projection of fragments of appreciable
size or range is to be expected. An external fire must not cause
virtually instantaneous explosion of almost the entire contents of
the package (49 CFR 1973.50).
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l.4S: Substance or article so packed or designed
At i|\ that any hazardous effects arising from accidental
I ■ ** \. functioning are limited to the extent that they do
n0| significantly hinder or prohibit fire fighting
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or other emergency response efforts in the
immediate vicinity of the package (49 CFR 173.52).
cartridges in combination with the firing assembly mix constitutes use
of explosives. Do not be confused by claims of “nondetonating” or
“nonexplosive.” Any product labeled as 1 .4S is within the scope of the
North Carolina blasting standards.
You may find North Carolina’s amendments to the federal 0SI1A
Blasting and the Use of Explosives Standard at www.nclabor.com/oshai'
etta/state_specific_rules/7fD7.pdf. Compliance with the applicable blasting
in construction standards can help prevent similar injuries as the one
described in this hazard alert. Several highlights about blaster qualifi¬
cations and handling of misfires are listed below. Please incorporate
them when handling explosives on your construction site.
4" The blasting standard requires blasters to be “qualified, by reason
of training, knowledge, or experience, in the field of transporting,
storing, handling, and use of explosives, and have a working
knowledge of State, federal and local laws and regulations which
pertain to explosives.”
4" Additionally, the employer must require the blaster “to furnish
evidence satisfactory to the employer of competency in handling
explosives and performing in a safe manner the type of blasting
that will be required.”
4" Sufficient time must be allowed, not less than 15 minutes in tunnels,
for the smoke and fumes to dissipate before returning to the blast
site. Subsequently, the blaster must inspect the blast site and sur¬
rounding nibble for signs of misfires.
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