CES Explosives Safety & Handling 2 — Questions and Answers
Question 1: What minimum separation distance is required between a detonator magazine and a high explosives magazine under ATF regulations?
- 50 feet
- 100 feet (Correct answer)
- 150 feet
- 200 feet
Correct answer: 100 feet
ATF regulations require a minimum of 100 feet separation between detonator (blasting cap) magazines and high explosives magazines to prevent sympathetic detonation.
Question 2: Which condition makes it MOST dangerous to use electric blasting caps?
- Low humidity below 20%
- Proximity to radio frequency transmitters (Correct answer)
- Ambient temperature above 90°F
- Wind speeds exceeding 15 mph
Correct answer: Proximity to radio frequency transmitters
Radio frequency energy from transmitters can induce stray currents in electric blasting cap leg wires, causing accidental initiation.
Question 3: When conducting a post-blast inspection after a misfire, what is the FIRST action a blaster must take?
- Immediately re-enter the blast area to locate the misfire
- Wait at least 30 minutes before approaching in a hot blast and 1 hour for a cold blast (Correct answer)
- Flood the borehole with water immediately
- Call the explosives manufacturer for guidance
Correct answer: Wait at least 30 minutes before approaching in a hot blast and 1 hour for a cold blast
Waiting the mandated time (30 min for hot/warm blasts, 1 hour for cold/wet conditions) allows unstable material to stabilize before personnel approach.
Question 4: Under OSHA 29 CFR 1926.912, when must all persons and vehicles be cleared from the blast area?
- After the blaster primes the first hole
- Before connecting the detonating circuit (Correct answer)
- After the blaster calls out a 5-minute warning
- Once the blast area is flagged
Correct answer: Before connecting the detonating circuit
OSHA requires all personnel and vehicles to be removed from the blast area before the blasting circuit is connected to prevent accidental initiation while people are present.
Question 5: What does the term 'sympathetic detonation' refer to in explosives handling?
- Accidental initiation caused by stray electrical current
- Detonation of one explosive charge triggered by the shock wave of an adjacent charge (Correct answer)
- The planned sequential firing of multiple charges
- A detonator firing without a blasting machine
Correct answer: Detonation of one explosive charge triggered by the shock wave of an adjacent charge
Sympathetic detonation occurs when the shock energy from one exploding charge initiates a nearby unconnected charge without direct electrical or physical connection.
Question 6: Which storage requirement applies specifically to black powder under 27 CFR Part 555?
- It may be stored with high explosives in the same magazine
- It must be stored in a Type 4 magazine separate from high explosives (Correct answer)
- It requires no special magazine if quantity is under 25 lbs
- It can be stored with detonators if separated by a wooden partition
Correct answer: It must be stored in a Type 4 magazine separate from high explosives
Black powder must be stored in a Type 4 magazine and kept separate from other explosive materials because it is more sensitive to heat and friction.
Question 7: A blaster discovers an electric blasting cap leg wire has been cut during hole loading. What is the correct action?
- Splice the wires together and continue loading
- Remove the cap from the hole carefully and treat it as a misfire (Correct answer)
- Leave it in the hole and detonate the shot without connecting that cap
- Insert a new cap alongside the damaged one
Correct answer: Remove the cap from the hole carefully and treat it as a misfire
A damaged electric blasting cap must be carefully removed and treated as a misfire; splicing or bypassing it risks accidental detonation or a failed blast.
CES Explosives Safety & Handling 2
What minimum separation distance is required between a detonator magazine and a high explosives magazine under ATF regulations?