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TL;DR

Study the specific conditions under which tap conductors may be used without overcurrent protection at their point of supply. Tap rules in NEC 240.21 are detail-heavy and a favorite topic for exam writers.

By Valenke Exam Prep Team·Last updated 2026-06-03

Free Tap Rules (240.21) Practice Questions

Journeyman Electrician License Exam · Overcurrent Protection

This module covers Tap Rules (240.21) as part of the Overcurrent Protection section, testing your understanding of core concepts and their practical application.

ExamJourneyman Electrician License Exam
Pass Rate55%
Duration240 minutes
ModuleTap Rules (240.21)

Why Tap Rules (240.21) matters

Tap Rules (240.21) is a commonly tested topic on the Journeyman Electrician License Exam because it covers fundamental knowledge required for competent professional practice.

Sample Practice Questions (5)

1. Per NEC 240.21(B)(1), which of the following is an additional requirement for a 10-foot tap conductor?

  • The tap conductors shall be enclosed in a raceway that extends from the tap to the overcurrent device at the other end
  • The tap conductors must be installed in free air only
  • The tap conductors must be a minimum of 4/0 AWG
  • The tap point must be accessible only to qualified persons — no enclosure is required

2. Per NEC 240.21(B)(2), for a 25-foot tap, the tap conductors must have an ampacity not less than what fraction of the feeder OCPD rating?

  • 1/2
  • 1/4
  • 1/3
  • 1/10

3. A feeder is protected by a 400-ampere OCPD. An electrician needs to install a 25-foot tap to supply a sub-panel. Per NEC 240.21(B)(2), what is the minimum required ampacity of the tap conductors?

  • 133 amperes (one-third of 400A)
  • 200 amperes (one-half of 400A)
  • 100 amperes (one-quarter of 400A)
  • 40 amperes (10% of 400A)

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4. Per NEC 450.3(B), a transformer rated 600V or less with a primary OCPD sized at not more than 125% of rated primary current does not require secondary protection when the secondary current is 9A or more. For a 25 kVA single-phase transformer with a 480V primary and 240V secondary, what is the maximum primary OCPD?

  • 60A
  • 70A
  • 50A
  • 80A

5. Per NEC 240.21(B)(1), what is the maximum length permitted for a 10-foot tap conductor?

  • 10 feet (3 m)
  • 25 feet (7.5 m)
  • 15 feet (4.5 m)
  • 50 feet (15 m)

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Frequently Asked Questions

How many Tap Rules (240.21) questions are on the Journeyman Electrician License Exam?▼
The Overcurrent Protection section, which includes Tap Rules (240.21), typically represents a significant portion of the exam. Focus on understanding core concepts rather than memorizing exact question counts, as the exam uses adaptive testing.
What is the best way to study Tap Rules (240.21)?▼
Use active recall and spaced repetition rather than passive reading. Practice with realistic exam questions, review explanations for both correct and incorrect answers, and focus on understanding the reasoning behind each concept.
What topics within Tap Rules (240.21) should I focus on most?▼
Focus on the concepts that appear in our practice questions and any areas where you consistently score below 70%. The adaptive practice mode will automatically target your weak areas for efficient study.