IBEW Reading Comprehension Analysis 4 — Questions and Answers
Question 1: A passage reads: 'Overcurrent protection devices must be rated at least equal to the conductor's ampacity, but not more than the maximum rating permitted for the load.' A conductor has an ampacity of 30 A serving a load with a maximum permitted breaker of 20 A. What breaker size is correct?
- 30 A, because the conductor's ampacity sets the minimum
- 20 A, because the load's maximum permitted rating governs (Correct answer)
- 25 A, as a compromise between the two values
- 40 A, to provide a safety margin above ampacity
Correct answer: 20 A, because the load's maximum permitted rating governs
When the load's maximum permitted rating is lower than the conductor's ampacity, the load's rating governs.
Question 2: A technical bulletin states: 'GFCI protection is required in bathrooms, garages, crawl spaces, unfinished basements, boathouses, and outdoors.' A homeowner asks if the garage receptacle needs GFCI protection. What does the bulletin indicate?
- Only if the garage is attached to the house
- Only if the garage has running water
- Yes, garages are explicitly listed as requiring GFCI protection (Correct answer)
- No, garages are exempt if the circuit is dedicated
Correct answer: Yes, garages are explicitly listed as requiring GFCI protection
The bulletin explicitly lists garages as one of the locations requiring GFCI protection.
Question 3: A passage explains: 'Reactive power (VAR) does no useful work but must be supplied by the generator. Power factor is the ratio of real power (W) to apparent power (VA). A low power factor increases current demand for the same real power output.' Why does low power factor increase current demand?
- Because reactive power heats the conductors and reduces their capacity
- Because more current must flow to deliver the same real power when apparent power is high (Correct answer)
- Because generators produce less voltage at low power factors
- Because capacitors are needed to correct the power factor
Correct answer: Because more current must flow to deliver the same real power when apparent power is high
Low power factor means more apparent power (and thus more current) is needed to deliver the same amount of real work.
Question 4: A work procedure states: 'When splicing conductors in a junction box, the splice must be accessible without disturbing the building structure.' A splice is made inside a wall cavity with no access panel. Does this comply?
- Yes, if the splice is properly insulated with wire nuts
- No, the splice must be accessible without disturbing the structure (Correct answer)
- Yes, if the junction box is labeled on the outside of the wall
- No, splices are never permitted inside walls
Correct answer: No, the splice must be accessible without disturbing the structure
The procedure requires accessibility without disturbing the building structure; a splice hidden in a wall cavity fails this requirement.
Question 5: A passage reads: 'The neutral conductor in a balanced three-phase system carries no current because the currents from each phase cancel each other out. In an unbalanced system, the neutral carries the difference.' A three-phase system has Phase A at 20 A, Phase B at 20 A, and Phase C at 20 A. How much current flows in the neutral?
- 60 A
- 20 A
- 0 A (Correct answer)
- 6.67 A
Correct answer: 0 A
A perfectly balanced three-phase system has zero neutral current because the three phase currents cancel.
Question 6: A code provision states: 'Service entrance conductors shall not pass through the interior of a building except where installed in service entrance cable or in a raceway.' Bare service entrance conductors are routed through a basement ceiling. Is this permitted?
- Yes, basements are below grade and exempt from interior routing rules
- No, they must be in a cable assembly or raceway to pass through interior spaces (Correct answer)
- Yes, if the conductors are insulated with 600 V-rated insulation
- No, service entrance conductors can never enter a building
Correct answer: No, they must be in a cable assembly or raceway to pass through interior spaces
The provision requires interior routing to use service entrance cable or a raceway; bare conductors do not comply.
Question 7: An apprenticeship test passage states: 'Reading a wiring diagram requires identifying symbols for components, tracing the current path from source to load, and recognizing how switches and protective devices interrupt that path.' A student can identify all symbols but cannot trace a current path. What skill is still missing?
- Symbol identification
- Tracing the current path from source to load (Correct answer)
- Recognizing how protective devices work
- All skills are present since symbols are identified
Correct answer: Tracing the current path from source to load
The passage lists three skills; the student has only the first and needs to develop current-path tracing.
IBEW Reading Comprehension Analysis 4
A passage reads: 'Overcurrent protection devices must be rated at least equal to the conductor's ampacity, but not more than the maximum rating permitted for the load.' A conductor has an ampacity of 30 A serving a load with a maximum permitted breaker of 20 A.
What breaker size is correct?