IEC Electrical Safety Practices 5 — Questions and Answers
Question 1: What does 'flash protection boundary' mean in NFPA 70E arc flash terminology?
- The maximum working distance allowed for any electrical task
- The distance at which incident energy equals 1.2 cal/cm², requiring arc-rated PPE beyond this point (Correct answer)
- The distance at which voltage becomes hazardous
- The boundary marking where rubber gloves must be worn
Correct answer: The distance at which incident energy equals 1.2 cal/cm², requiring arc-rated PPE beyond this point
The flash protection boundary (arc flash boundary) is the distance at which incident energy equals 1.2 cal/cm²; workers inside this boundary must wear arc-rated PPE.
Question 2: A portable generator on a construction site must have GFCI protection or an Assured Equipment Grounding Conductor Program (AEGCP). What is the key inspection requirement under the AEGCP?
- Visual inspection of cords each morning
- Testing of all equipment before first use, after any incident, and at intervals not exceeding 3 months (Correct answer)
- Annual third-party certification of all cords and tools
- Monthly megohm testing of all cords
Correct answer: Testing of all equipment before first use, after any incident, and at intervals not exceeding 3 months
The AEGCP requires equipment inspection before first use, after suspected damage, and at regular intervals not exceeding 3 months, with documented records.
Question 3: When should electrical workers perform a pre-task safety briefing?
- Only at the beginning of a new project
- Before each shift regardless of task similarity
- Before beginning each new task or when conditions change during a shift (Correct answer)
- Once per week at the safety meeting
Correct answer: Before beginning each new task or when conditions change during a shift
Pre-task safety briefings should occur before each new task and whenever conditions change, ensuring all workers are aware of current hazards and controls.
Question 4: What is the danger of 'touch potential' when working near a grounded electrical system experiencing a fault?
- The equipment becomes permanently magnetized
- A worker touching grounded equipment can complete a circuit to ground if standing on earth at a different potential (Correct answer)
- Touch potential only applies to ungrounded systems
- It causes insulation breakdown on nearby cables
Correct answer: A worker touching grounded equipment can complete a circuit to ground if standing on earth at a different potential
Touch potential occurs when a grounded structure rises in potential during a fault; a worker touching it while standing on the earth can receive a shock due to the voltage difference.
Question 5: Which of the following is an example of an administrative control for electrical safety?
- Installing insulating barriers around live parts
- Requiring two-person teams for energized work above a certain voltage threshold (Correct answer)
- Using Class E hard hats on site
- Installing GFCI outlets in wet locations
Correct answer: Requiring two-person teams for energized work above a certain voltage threshold
Administrative controls are procedural measures such as requiring two-person teams, as opposed to engineering controls like barriers or PPE.
Question 6: What is the maximum voltage at which rubber insulating gloves alone (without leather protectors) may be used under ASTM F696?
- Leather protectors are always required with rubber gloves (Correct answer)
- 240V or less for light duty use per ASTM F696
- 1,000V if the gloves are Class 1 or higher
- Rubber gloves may never be used without leather protectors
Correct answer: Leather protectors are always required with rubber gloves
ASTM F696 and NFPA 70E require leather protectors over rubber insulating gloves whenever the gloves are used for electrical protection; no exception exists for use without protectors.
Question 7: During an emergency involving an electrical contact victim, what should a first responder do FIRST?
- Immediately grab the victim and pull them away from the source
- Call 911 and begin CPR without delay
- Ensure the power source is de-energized or the victim is safely separated from it before contact (Correct answer)
- Apply a tourniquet to any burned limbs
Correct answer: Ensure the power source is de-energized or the victim is safely separated from it before contact
The first responder must never touch the victim while they are still in contact with an energized source — de-energize the circuit or use a non-conductive object to break contact first.
IEC Electrical Safety Practices 5
What does 'flash protection boundary' mean in NFPA 70E arc flash terminology?