Journeyman Electrician's Overcurrent Protection Flashcards
7 cards from real Journeyman Electrician’s Exam practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Journeyman Electrician's Overcurrent Protection flashcards as text
Where must an overcurrent device be located relative to the point where a conductor receives its supply?
Answer: At the point where the conductor receives its supply
NEC 240.21 requires OCPDs to be placed at the point where the conductor receives its supply unless a tap rule exception applies.
A feeder tap conductor using the 10-foot tap rule must have an ampacity of at least what percentage of the overcurrent device protecting the feeder?
Answer: 33%
NEC 240.21(B)(1) requires the tap conductor's ampacity to be at least one-third (33%) of the feeder OCPD rating for the 10-foot tap rule.
Which of the following best describes an 'inverse-time' circuit breaker?
Answer: It trips faster as the current increases
An inverse-time breaker has a trip time that decreases as the overcurrent magnitude increases, providing time-current coordination.
A fused disconnect for an air-conditioning unit must be installed within sight of and readily accessible from the unit. Which article covers this requirement?
Answer: Article 440
NEC Article 440 covers air-conditioning and refrigerating equipment, including the disconnecting means and overcurrent protection requirements.
What is the maximum OCPD size allowed for a 15 AWG copper conductor used in a branch circuit?
Answer: 15 amperes
NEC 240.4(D)(3) limits the OCPD for 14 AWG to 15A; 15 AWG is not a standard branch-circuit size, so 14 AWG rules (15A max) apply.
Ground-fault circuit interrupter (GFCI) protection detects current imbalances as small as:
Answer: 5 milliamperes (±1 mA)
GFCI devices are designed to trip when they sense a ground-fault current of approximately 4–6 mA (nominally 5 mA ±1 mA).
Which conductor is NOT required to be protected by an overcurrent device under NEC 240.22?
Answer: Grounded (neutral) conductors
NEC 240.22 prohibits placing an OCPD in series with the grounded conductor unless the device opens all conductors simultaneously.