NEC Article 230 Practice Questions: Services

Service disconnects, service-entrance conductors, and clearances — Article 230 questions are lookup-heavy and very learnable. Drill the ones that actually get asked.

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46 Article 230 questions in the bankWritten in the PSI computer-based exam formatEvery answer cites the NEC section

What Article 230 Covers on the Exam

Article 230 governs everything from the utility connection to the service disconnecting means: overhead and underground service conductors, clearances over roofs and driveways, service-entrance cable rules, where the disconnect must be located (230.70), and how many disconnects are allowed (230.71). Exam questions are mostly direct lookups — clearance heights and disconnect rules are the favorites.

Tested subtopics from Article 230

Overhead service conductor clearances over roofs, driveways, and pools — 230.24
Service disconnect location: nearest the point of entrance — 230.70(A)(1)
Maximum number of service disconnects — 230.71
Service-entrance conductor sizing and rating — 230.42 and 230.79
Working on the supply side: what may be connected ahead of the disconnect — 230.82

Drill a different article

46 questions in our bank cite Article 230. Practice the other high-yield articles too:

Art. 110 — General Requirements Art. 210 — Branch Circuits Art. 220 — Load Calculations 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 230

Tab 230.24 (clearances) and memorize the big four heights: 8 ft over roofs (with the 3-ft exception for steep roofs), 10 ft at the service entrance, 12 ft over residential driveways, and 18 ft over public streets. Then learn 230.70 and 230.71 as a pair — where the disconnect goes and how many you can have — because exam writers combine them in one question.

Then put it under exam conditions: the free diagnostic scores you across every category and shows whether services 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 230.70(A)(1)Services & Separately Derived Systems

1. Per NEC 230.70(A)(1), the service disconnecting means shall be installed at a readily accessible location either outside of a building or structure or inside nearest the point of entrance of the service conductors. What is this requirement commonly known as?

AThe service entrance rule
BThe readily accessible rule
CThe nearest point of entry rule
DThe service disconnect location rule

Show explanation

NEC 230.70(A)(1) establishes the requirement that the service disconnect be at the nearest point of entry of service conductors.

NEC NEC 230.28Branch Circuits

2. What does NEC 2023 require for a service mast used as a support for service-entrance conductors?

AThe service mast must be located at least 3 feet from the building wall
BThe service mast shall have adequate strength or be supported by braces or guy wires to safely withstand the strain imposed by the service conductors
CThe mast must be supported on at least two guy wires
DNo support requirement if properly grounded

Show explanation

Per NEC 2023 230.28, a service mast used for the support of service-entrance conductors shall have adequate strength or be supported by braces or guy wires to safely withstand the strain imposed by the overhead service conductors. Note: NEC 225.17 covers feeder and branch-circuit masts, not service masts.

NEC NEC 230.2Services & Separately Derived Systems

3. How many services may be supplied to a building under normal conditions?

AOnly one service is permitted
BTwo services are permitted without exception
COne service is the general rule, but exceptions allow additional services
DAn unlimited number of services may be supplied

Show explanation

Per NEC 230.2, one service is the general rule for a building. However, exceptions allow additional services for specific conditions such as different voltages, capacities, or supply sources, or where required by the serving utility.

NEC NEC 230.6Services & Separately Derived Systems

4. Under which condition are service conductors considered to be outside a building, per NEC 230.6?

AWhen installed above the roof line by more than 5 feet
BWhen installed under not less than 50 mm (2 in.) of concrete beneath the building
CWhen installed from the utility point of delivery to the point of entrance to the building
DWhen installed in conduit above grade on the exterior wall

Show explanation

Per NEC 230.6, conductors are considered outside the building when they meet one of five specific conditions, including: (1) installed under not less than 50 mm (2 in.) of concrete beneath the building; (2) installed in a raceway encased in not less than 50 mm (2 in.) of concrete or masonry inside the building; (3) installed in a vault meeting Article 450; (4) in RMC or IMC beneath not less than 450 mm (18 in.) of earth beneath the building; or (5) installed through the eave in RMC or IMC. Simply running from the utility meter to the entrance point does not qualify under any 230.6 condition.

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Frequently Asked Questions

What does NEC Article 230 cover on the exam?

Article 230 covers services: overhead and underground service conductors, clearances (230.24), service-entrance cables, the service disconnecting means location (230.70), the maximum number of disconnects (230.71), and what may be connected on the supply side (230.82).

Where must the service disconnect be located?

Per 230.70(A)(1), the service disconnecting means must be installed at a readily accessible location either outside the building or inside nearest the point of entrance of the service conductors. "Nearest the point of entrance" is the phrase exam answers hinge on.

What are the minimum clearances for overhead service conductors?

Per 230.24: generally 8 ft above roofs (reduced to 3 ft where the roof slope is 4-in-12 or greater under conditions), 10 ft above finished grade at the service entrance and sidewalks, 12 ft over residential property and driveways, and 18 ft over public streets, alleys, and roads.