IMSA Electrical Safety & Lockout/Tagout 1 — Questions and Answers
Question 1: According to OSHA 29 CFR 1910.147, which step must be completed FIRST when performing lockout/tagout on energy-isolating equipment?
- Notify affected employees of the shutdown (Correct answer)
- Apply the lockout device to the energy source
- Verify that the equipment is de-energized
- Release any stored energy
Correct answer: Notify affected employees of the shutdown
OSHA 1910.147 requires that affected employees be notified before any lockout/tagout procedure begins.
Question 2: What is the minimum approach distance for qualified electrical workers working on unguarded, energized parts operating at 50 volts in the US?
- No minimum distance required; insulated tools must be used (Correct answer)
- Avoid contact — no specified air gap at 50V
- 1 foot clearance required
- 3 feet clearance required
Correct answer: No minimum distance required; insulated tools must be used
NFPA 70E specifies that at voltages below 50V the shock hazard threshold is not met, but at 50V qualified workers must use insulated tools and avoid contact.
Question 3: Under OSHA's Control of Hazardous Energy standard, who is authorized to remove a lockout/tagout device?
- Any supervisor on site
- Only the employee who applied the device (Correct answer)
- The safety officer
- Any qualified electrician
Correct answer: Only the employee who applied the device
OSHA 1910.147 states that only the authorized employee who applied the lockout/tagout device may remove it, except under specific emergency removal procedures.
Question 4: Which of the following is classified as an 'energy-isolating device' under OSHA 1910.147?
- A control button that de-energizes equipment
- A manually operated disconnect switch (Correct answer)
- An electronic interlock
- A software-based shutdown command
Correct answer: A manually operated disconnect switch
A manually operated disconnect switch physically isolates energy and qualifies as an energy-isolating device under OSHA 1910.147.
Question 5: What type of inspection does OSHA 1910.147 require for energy control procedures at least annually?
- A documented periodic inspection of each procedure (Correct answer)
- A quarterly audit by an outside contractor
- A monthly self-certification by the employee
- A biennial review by OSHA compliance officers
Correct answer: A documented periodic inspection of each procedure
OSHA requires an annual documented inspection of each energy control procedure to ensure the procedure is adequate and employees are familiar with it.
Question 6: In electrical safety, what does the term 'arc flash boundary' refer to?
- The distance at which an arc flash could cause a second-degree burn to unprotected skin (Correct answer)
- The zone where all electrical work is prohibited
- The maximum distance a worker must stand from any panel
- The boundary requiring full arc-rated PPE regardless of energy level
Correct answer: The distance at which an arc flash could cause a second-degree burn to unprotected skin
The arc flash boundary is the distance from exposed energized conductors at which a person could receive a second-degree burn (1.2 cal/cm²) if an arc flash occurred.
IMSA Electrical Safety & Lockout/Tagout 1
According to OSHA 29 CFR 1910.147, which step must be completed FIRST when performing lockout/tagout on energy-isolating equipment?