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TL;DR

Learn NEC Article 630 requirements for electric welder installations including conductor sizing, overcurrent protection, and duty cycle calculations. Welder circuits have unique sizing rules that differ from standard equipment.

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

Free Welders (Art. 630) Practice Questions

Master Electrician License Exam · Special Equipment

This module covers Welders (Art. 630) as part of the Special Equipment section, testing your understanding of core concepts and their practical application.

ExamMaster Electrician License Exam
Pass Rate45%
Duration300 minutes
ModuleWelders (Art. 630)

Why Welders (Art. 630) matters

Welders (Art. 630) is a commonly tested topic on the Master Electrician License Exam because it covers fundamental knowledge required for competent professional practice.

Sample Practice Questions (5)

1. A resistance welder has a nameplate primary current of 60 amperes and a duty cycle of 50%. Per NEC 630.31(A)(2), using the 50% duty cycle multiplier of 0.71, what is the minimum supply conductor ampacity?

  • 42.6 amperes
  • 60 amperes
  • 75 amperes
  • 30 amperes

2. Three arc welders on a common feeder have the following duty-cycle-adjusted primary currents: Welder 1 = 45A, Welder 2 = 40A, Welder 3 = 30A. Per NEC 630.11(B), what is the minimum feeder conductor ampacity?

  • 110.5 amperes
  • 115 amperes
  • 85 amperes
  • 143.75 amperes

3. An arc welder has a nameplate rating of 80A primary at 60% duty cycle. The duty cycle multiplier for 60% is 0.78. What is the maximum overcurrent protection permitted for this welder per NEC 630.12(A)?

  • 160 amperes
  • 124.8 amperes
  • 100 amperes
  • 200 amperes

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4. An arc welder has a nameplate rating of 50 amperes primary current with a duty cycle multiplier of 0.71. What is the minimum ampacity of the supply conductors?

  • 35.5 amperes
  • 50 amperes
  • 62.5 amperes
  • 25 amperes

5. Per NEC 630.12(A), overcurrent protection for an arc welder shall not exceed what percentage of the rated primary current of the welder?

  • 200%
  • 150%
  • 125%
  • 300%

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Frequently Asked Questions

How many Welders (Art. 630) questions are on the Master Electrician License Exam?▼
The Special Equipment section, which includes Welders (Art. 630), 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 Welders (Art. 630)?▼
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 Welders (Art. 630) 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.