NEC Article 110 Practice Questions: General Requirements

Working space clearances, terminal temperature ratings, and interrupting ratings — the Article 110 questions that show up on every journeyman exam, with the code reference behind every answer.

Start Free Diagnostic See Sample Questions

31 Article 110 questions in the bankWritten in the PSI computer-based exam formatEvery answer cites the NEC section

What Article 110 Covers on the Exam

Article 110 sets the ground rules for every installation: how much working space equipment needs, which conductor temperature rating governs at a termination, interrupting ratings, and how equipment must be marked and used. Exam writers love it because the answers are short lookups with precise numbers — Table 110.26(A)(1) depth-of-working-space questions are near-guaranteed on the Texas journeyman exam.

Tested subtopics from Article 110

Working space depth, width, and height about electrical equipment — Table 110.26(A)(1) and 110.26(A)(2)
Dedicated equipment space for panelboards — 110.26(E)
Terminal temperature ratings: when to size from the 60°C vs 75°C column — 110.14(C)
Interrupting rating of overcurrent devices — 110.9 and 110.10
Listing, labeling, and suitability of equipment — 110.3(B)

Drill a different article

31 questions in our bank cite Article 110. Practice the other high-yield articles too:

Art. 210 — Branch Circuits Art. 220 — Load Calculations Art. 230 — Services Art. 240 — Overcurrent Protection Art. 250 — Grounding and Bonding Art. 300 — Wiring Methods Art. 310 — Conductors & Ampacity Art. 314 — Boxes & Box Fill Art. 430 — Motors Art. 450 — Transformers Art. 680 — Swimming Pools & Spas

How to Study Article 110

Memorize the three working-space conditions in Table 110.26(A)(1) (3 ft / 3.5 ft / 4 ft at 0–150 V and 151–600 V) instead of looking them up — it is one of the highest-frequency lookups on the exam and knowing it cold buys you time for the calculation questions. For everything else in Article 110, tab 110.14(C) and practice deciding which temperature column applies before you touch the ampacity tables.

Then put it under exam conditions: the free diagnostic scores you across every category and shows whether general requirements is actually a weak area — or whether your study time belongs somewhere else.

Sample Questions (From Our Real Question Bank)

Here are 4 real questions from our question bank. The free diagnostic quiz has 10 more.

NEC NEC 110.26(A)(1)General Requirements & Definitions

1. According to NEC 110.26(A)(1), what is the minimum clear working space depth in front of electrical equipment operating at 120 volts to ground with exposed live parts on one side and no live or grounded parts on the other side (Condition 1)?

A2.5 feet
B3 feet
C3.5 feet
D4 feet

Show explanation

Per NEC 110.26(A)(1), Condition 1 requires a minimum depth of 3 feet for equipment operating at 120V with exposed live parts on one side only.

NEC NEC 110.26(A)Equipment & Devices

2. The clearance required in front of a panelboard serving a residential installation is:

ANot less than 18 inches
BNot less than 30 inches wide and 36 inches deep (Condition 1), with 6½ ft headroom
CNot less than 48 inches in all directions
DThere is no minimum clearance requirement

Show explanation

Per NEC 110.26(A), working space about a panelboard shall be at least 30 in. wide (110.26(A)(2)), 6½ ft high (110.26(A)(3)), and, per Table 110.26(A)(1), 3 ft deep for 0–150 V to ground under Condition 1. These dimensions apply to dwelling panelboards as well.

NEC NEC 110.2Other Code Topics

3. When must electrical equipment be approved?

AOnly when used in commercial installations
BOnly for loads exceeding 50 amperes
CAcceptable to the authority having jurisdiction with regard to listed and labeled equipment
DOnly during the initial installation, not replacements

Show explanation

Per NEC 110.2, all equipment shall be approved. This includes acceptance by the authority having jurisdiction and shall be recognized as suitable for the intended use.

NEC NEC 110.3Other Code Topics

4. What must be done with all listed or labeled equipment before installation?

AIt must be repainted with electrical safety markings
BIt must be examined to verify proper installation per manufacturer's instructions
CIt must be tested with high voltage to ensure safety
DIt must be registered with the AHJ

Show explanation

Per NEC 110.3(B), listed or labeled equipment shall be examined and identified, installed and used in accordance with the instructions included in the listing or labeling.

Take the Full Free Diagnostic →

Frequently Asked Questions

What does NEC Article 110 cover on the electrician exam?

Article 110 covers general installation requirements: working space around equipment (110.26), terminal temperature ratings (110.14), interrupting ratings (110.9), and equipment listing and use (110.3(B)). On the exam these appear as short lookup questions with exact numeric answers.

What are the NEC working space requirements in 110.26?

For equipment operating at 0–150 V to ground, the minimum depth of working space is 3 ft in all conditions. At 151–600 V it is 3 ft (Condition 1), 3.5 ft (Condition 2), or 4 ft (Condition 3), per Table 110.26(A)(1). Width is the width of the equipment or 30 inches, whichever is greater, and headroom is generally 6.5 ft.

When do I use the 60°C column instead of the 75°C column?

Per 110.14(C), circuits rated 100 A or less (or with 14 AWG–1 AWG conductors) are sized from the 60°C column unless the terminations are listed and marked for 75°C. Circuits over 100 A use the 75°C column. This termination check comes before any ampacity correction or adjustment.