CEA Safety Standards & Regulations 4 — Questions and Answers
Question 1: What NEC requirement applies to electrical panels installed in clothes closets?
- Panels are permitted if surface-mounted
- Panels are not permitted in clothes closets (Correct answer)
- Panels are allowed if the closet is larger than 36 sq ft
- Panels are permitted if GFCI-protected
Correct answer: Panels are not permitted in clothes closets
NEC 240.24(D) prohibits overcurrent devices (and therefore panels) from being located in the vicinity of easily ignitable material, which includes clothes closets.
Question 2: Under OSHA 1926 Subpart K, which action is required when working within 10 feet of overhead power lines rated over 50kV?
- Use insulated tools only
- Have the lines de-energized or maintain increased clearance per line voltage (Correct answer)
- Wear rubber gloves
- Post a spotter within 5 feet of the lines
Correct answer: Have the lines de-energized or maintain increased clearance per line voltage
OSHA 1926.1408 requires that for voltages over 50kV, clearance distances increase beyond 10 feet, and work may only proceed if lines are de-energized or proper clearance is maintained.
Question 3: What is the voltage threshold above which OSHA requires electrical equipment to be guarded against accidental contact?
- 50 volts (Correct answer)
- 120 volts
- 240 volts
- 600 volts
Correct answer: 50 volts
OSHA 1910.303(g) requires guarding of live parts operating at 50 volts or more to prevent accidental contact.
Question 4: Which type of fire extinguisher is rated for use on electrical equipment fires?
- Class A
- Class B
- Class C (Correct answer)
- Class D
Correct answer: Class C
Class C extinguishers use non-conductive agents (CO2 or dry chemical) rated for energized electrical equipment fires.
Question 5: An apprentice notices a coworker bypassing a GFCI on a construction site. What is the correct action?
- Ignore it — GFCIs are optional on construction sites
- Report it to the supervisor or safety officer immediately (Correct answer)
- Replace the GFCI with a standard outlet
- Continue working and document it at shift end
Correct answer: Report it to the supervisor or safety officer immediately
Bypassing required GFCI protection violates OSHA 1926.404(b)(1) and must be reported immediately to prevent electrocution hazards.
Question 6: What is 'double insulation' on power tools, and why does it affect grounding requirements?
- Two layers of rubber coating that eliminate the need for a grounding conductor in the tool
- A UL-listed internal barrier and external housing that prevents fault current from reaching the user, eliminating the need for a grounding conductor (Correct answer)
- Metal casing with plastic handles
- Two separate circuit breakers protecting a single tool
Correct answer: A UL-listed internal barrier and external housing that prevents fault current from reaching the user, eliminating the need for a grounding conductor
Double-insulated tools have a UL-listed internal insulation system that prevents shock without a grounding conductor, so they use two-prong plugs legally.
Question 7: According to NEC 110.9, overcurrent protective devices must have an interrupting rating sufficient to handle:
- The normal load current only
- The available fault current at the point of application (Correct answer)
- Twice the circuit ampacity
- The voltage rating of the circuit
Correct answer: The available fault current at the point of application
NEC 110.9 requires that overcurrent devices have an interrupting rating equal to or greater than the available fault current at their point of installation.
CEA Safety Standards & Regulations 4
What NEC requirement applies to electrical panels installed in clothes closets?