MSHA Explosives and Blasting

Question 1

Under MSHA regulations, who is authorized to handle and use explosives in underground mines?

Accepted Answer

A certified blaster who holds a valid blaster's certificate

Answer

Any miner with at least 5 years of experience

Answer

The mine foreman or shift supervisor only

Answer

Any employee who has completed a 4-hour safety course

Question 2

What is the minimum distance that must be maintained between detonators (blasting caps) and other explosives during transportation in a mine?

Accepted Answer

Detonators must be transported separately from other explosives

Answer

6 inches

Answer

12 inches

Answer

At least 50 feet

Question 3

Before loading explosives into a borehole, MSHA requires that the hole be checked with which of the following?

Accepted Answer

A wooden or non-sparking loading stick

Answer

A metal tamping rod

Answer

A steel probe to detect water

Answer

A voltage tester for stray currents

Question 4

According to MSHA standards, what must be done if a misfire (failed blast) is suspected in an underground coal mine?

Accepted Answer

Wait at least 30 minutes before returning and follow specific misfire procedures

Answer

Re-enter the blast area after 5 minutes

Answer

Immediately flood the area with water

Answer

Send a single trained employee to inspect after 10 minutes

Question 5

What type of container is required by MSHA for storing electric detonators (blasting caps) at a mine site?

Accepted Answer

A separate locked magazine, apart from other explosives

Answer

A locked wooden box painted red

Answer

A plastic bucket with a sealed lid

Answer

A metal locker inside the main explosive magazine

Question 6

Under MSHA rules for underground coal mines (30 CFR Part 75), permissible explosives are required because they:

Accepted Answer

Produce a flame and gas that will not ignite coal dust or methane

Answer

Are cheaper than standard industrial explosives

Answer

Can be detonated without electric blasting caps

Answer

Are waterproof and can be used in wet conditions

Question 7

What does MSHA require regarding the posting of warning signs during blasting operations?

Accepted Answer

Warning signs must be posted at all entrances to the blast area before detonation

Answer

Signs are optional if verbal warnings are given

Answer

Signs must be posted only when blasting near a public road

Answer

A single sign at the mine entrance is sufficient