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MASTER NEC 2023

Master Electrician Practice Test 13 – Service Entrance & Outside Wiring Design

This is Master Electrician Practice Test 13 — Service Entrance & Outside Wiring Design, covering the Article 230 service rules and the Article 225 outside branch circuit and feeder rules the master exam expects you to apply, not just memorize. The test has 25 multiple-choice questions on service disconnect location and rating, the emergency disconnect rule for dwellings, overhead service installation details, service point and service drop/lateral definitions, and the parallel Article 225 rules for feeders and branch circuits run between buildings on the same property. Pass score is 70%. Every question includes a full NEC 2023 explanation so you can trace each answer back to the exact code section.

TOPICS COVERED

Service Entrance & Outside Wiring

How this test works

Read each question carefully

Look for absolute words like always / never — they often distinguish the right answer.

Manage your time

You have 45 min for 25 questions. Skip tough ones and come back.

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Review your answers

After submitting you'll see every explanation and your NEC references.

Frequently Asked Questions

Yes — completely free with no signup required. All answers include detailed explanations.

Requirements vary by state but typically include 4–8 years of documented electrical work experience plus a valid Journeyman license.

Advanced NEC code interpretation, load calculations, service entrance design, motor controls, generator systems, and electrical system design.

The Master exam focuses more on design, calculations, and planning rather than installation details. Load calculation and service sizing questions are weighted heavily.

Before You Start

25 questions — multiple choice
45 minutes to finish (timer starts when you begin)
Pass score is 70% — you need at least 18 correct answers
Full NEC 2023 explanation shown for every question after you submit

Topics in This Test

Service disconnect location — nearest point of entry, readily accessible (NEC 230.70(A))
Grouping and marking of multiple service disconnects (NEC 230.72(A))
Minimum service disconnect rating for a single branch circuit (NEC 230.79(A))
Minimum service disconnect rating for installations not covered elsewhere (NEC 230.79(D))
Outdoor emergency disconnect requirement for one- and two-family dwellings (NEC 230.85)
Service conductor clearance from windows, doors, and porches (NEC 230.9(A))
Service head location above the point of attachment (NEC 230.54(C))
Drip loops on overhead service conductors (NEC 230.54(F))
Service point definition (NEC Article 100)
Service drop vs. service lateral definitions (NEC Article 100)
Number of feeders/branch circuits to a second building — general one-feeder rule (NEC 225.30)
Disconnecting means required for each building supplied by a feeder (NEC 225.31)
Location of the outside feeder/branch-circuit disconnect (NEC 225.32)
Overhead clearance at the electrical service entrance to a building (NEC 225.18(1))
Service-entrance conductor ampacity — not less than the calculated load (NEC 230.42(A))
Service equipment marking — listed as suitable for service use (NEC 230.66)
Permitted wiring methods for service-entrance conductors (NEC 230.43)
Maximum number of disconnects for a feeder supplying a building (NEC 225.33)
Minimum service-drop conductor ampacity for a 100A dwelling service (NEC 230.31(B))
Grounded conductor identification — white, gray, or three continuous white stripes (NEC 200.6)
Exceptions to the single-service rule — fire pumps, multiple occupancy, capacity requirements (NEC 230.2)
Service mast support against the pull of service-drop conductors (NEC 230.28)
Feeder to a detached garage — governed by Article 225, not Article 230

Tip: The exam loves to test whether you know when a set of outside conductors is a "service" (Article 230, comes from the utility) versus a "feeder" or "branch circuit" (Article 225, comes from another building you already own). Ask yourself where the conductors originate before picking an article.

Questions

45 min

Time

70%

Pass

Timer starts immediately. Progress is auto-saved.

Master Electrician Practice Test 13 – Service Entrance & Outside Wiring Design — Question List

Question 1: NEC 230.70(A) requires the service disconnecting means to be located:

Anywhere in the building, regardless of accessibility
At a readily accessible location nearest the point of entrance of the service conductors
Only in a locked mechanical room
Only on the roof

NEC Reference: NEC 230.70(A)

Question 2: When a service has more than one disconnecting means, NEC 230.72(A) requires them to be:

Grouped and marked to indicate what each one serves
Scattered throughout the building for redundancy
Left unmarked, since drawings are sufficient
Installed only in pairs

NEC Reference: NEC 230.72(A)

Question 3: Under NEC 230.79(A), a service disconnect supplying a single branch circuit must have a minimum rating of:

15 amperes
30 amperes
60 amperes
100 amperes

NEC Reference: NEC 230.79(A)

Question 4: For an installation not otherwise covered by NEC 230.79(A) through (C) — such as most commercial services — what is the minimum service disconnect rating required by 230.79(D)?

30 amperes
60 amperes
100 amperes
200 amperes

NEC Reference: NEC 230.79(D)

Question 5: NEC 230.85 requires one- and two-family dwellings to have an emergency disconnecting means that is:

Installed indoors only, near the water heater
Outdoor and readily accessible, marked "EMERGENCY DISCONNECT"
Optional at the homeowner's discretion
Required only in flood zones

NEC Reference: NEC 230.85

Question 6: NEC 230.9(A) requires overhead service conductors to maintain what minimum clearance from windows, doors, and porches designed for human egress?

1 foot
3 feet
6 feet
10 feet

NEC Reference: NEC 230.9(A)

Question 7: Per NEC 230.54(C), the service head (weatherhead) on an overhead service must be located:

Below the point of attachment
Above the point of attachment
At the same height as the point of attachment, no exceptions
Anywhere on the roof

NEC Reference: NEC 230.54(C)

Question 8: NEC 230.54(F) requires what to be formed on individual overhead service-entrance conductors to prevent water from entering the service head?

A ground rod
A drip loop
A splice kit
A surge arrester

NEC Reference: NEC 230.54(F)

Question 9: Per NEC Article 100, the "service point" is defined as:

The main breaker location inside the panel
The point of connection between the serving utility and the premises wiring
The meter base only
The grounding electrode connection

NEC Reference: NEC Article 100

Question 10: What is the key difference between a service drop and a service lateral, per NEC Article 100?

A service drop is underground; a service lateral is overhead
A service drop is overhead; a service lateral is underground
They are two names for the same thing with no distinction
A service lateral only applies to three-phase services

NEC Reference: NEC Article 100

Question 11: A detached garage on the same property as a house, fed from the house's panel rather than directly from the utility, generally may receive how many feeders or branch circuits under NEC 225.30?

As many as the owner wants, with no restriction
Generally only one, absent a recognized exception
Exactly two, always
None — detached structures cannot be fed by feeders

NEC Reference: NEC 225.30

Question 12: NEC 225.31 requires each building or structure supplied by a feeder or branch circuit to have:

A disconnecting means at that building or structure
No disconnect, since the main service disconnect is sufficient
A dedicated transformer
A separate grounding electrode system only, no disconnect

NEC Reference: NEC 225.31

Question 13: NEC 225.32 requires the disconnecting means for an outside feeder or branch circuit to be located:

Readily accessible, nearest the point of entry of the conductors
Anywhere in the structure, accessibility not required
Only at the originating building
Underground, in a handhole

NEC Reference: NEC 225.32

Question 14: NEC 225.18(1) requires overhead conductors at the electrical service entrance to a building, rated 150 volts to ground or less, to maintain what minimum vertical clearance above finished grade?

8 feet
10 feet
12 feet
18 feet

NEC Reference: NEC 225.18(1)

Question 15: NEC 230.42(A) requires service-entrance conductors to have an ampacity of not less than:

The calculated load determined under Article 220
A flat 100A regardless of load
Half the main breaker rating
The utility transformer's nameplate rating

NEC Reference: NEC 230.42(A)

Question 16: NEC 230.66 requires service equipment to be:

Marked suitable for use as service equipment
Painted a specific color by code
Exempt from listing requirements
Rated for indoor use only, in all cases

NEC Reference: NEC 230.66

Question 17: Which of the following is NOT a permitted wiring method for service-entrance conductors under NEC 230.43?

Rigid metal conduit (RMC)
Electrical metallic tubing (EMT)
NM cable (Romex)
Service-entrance cable (SE)

NEC Reference: NEC 230.43

Question 18: Mirroring the six-disconnect rule for services in 230.71, NEC 225.33 permits how many disconnecting means for one set of feeder or branch-circuit conductors supplying a building?

Two
Four
Six
Unlimited

NEC Reference: NEC 225.33

Question 19: A single-family dwelling has a 100A service. What minimum ampacity must the service-drop conductors supplying that dwelling provide under NEC 230.31(B)?

60 amperes
80 amperes
100 amperes
125 amperes

NEC Reference: NEC 230.31(B)

Question 20: Per NEC 200.6, a grounded (neutral) service conductor may be identified by which color or marking?

Continuous white or gray, or three continuous white stripes
Continuous orange
Continuous black
Continuous green

NEC Reference: NEC 200.6

Question 21: NEC 230.2 generally limits a building to a single service, but recognizes exceptions. Which of the following is a recognized exception?

A dedicated fire pump service
Simple owner preference for redundancy
Lower installation cost
Aesthetic preference of the architect

NEC Reference: NEC 230.2

Question 22: NEC 230.28 requires a service mast used to support service-drop conductors to be:

Adequately strong or braced to withstand the strain of the service-drop conductors
Made only of PVC for weight savings
Installed with no support requirement at all
Limited to 4 feet in height

NEC Reference: NEC 230.28

Question 23: A homeowner runs an underground feeder from the main dwelling panel to power a detached workshop on the same lot. Which NEC article primarily governs this installation?

Article 230 — Services
Article 225 — Outside Branch Circuits and Feeders
Article 250 — Grounding and Bonding
Article 90 — Introduction

NEC Reference: NEC Article 225

Question 24: Which statement correctly distinguishes a "service" from a "feeder" under the NEC?

A service comes from the utility; a feeder comes from equipment already supplied by a service
A feeder always has higher voltage than a service
They are interchangeable terms with no legal distinction
A service can never supply more than one branch circuit

NEC Reference: NEC Article 100 / Article 225

Question 25: Underground service-lateral conductors installed by the utility are typically NOT subject to which set of NEC requirements?

NEC requirements in general — they are outside the NEC's scope until the service point
Local building permit fees
Utility company billing policy
OSHA jurisdiction entirely

NEC Reference: NEC Article 100 / 90.2

Key NEC References for This Test

Article	What It Covers
Art. 220	Load Calculations — optional and standard methods for multifamily
Art. 230	Services — service design, sizing, multiple disconnects
Art. 430	Motors — complete branch circuit design (conductor + OCPD + overload + disconnect)
Art. 445	Generators — standby systems, transfer switches
Art. 450	Transformers — sizing, primary/secondary OCPD, installation
Art. 706	Energy Storage Systems — battery/solar storage (major NEC 2026 expansion)

Study Tip: Practice transformer kVA calculations daily. Know the formula: I = kVA × 1000 ÷ (V × 1.732) for three-phase. This comes up on almost every master exam.

Master Electrician Practice Test 13 – Service Entrance & Outside Wiring Design

How this test works

Frequently Asked Questions

Before You Start

Topics in This Test

Electrician Reviews

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Key NEC References for This Test

Master Electrician Practice Test 13 – Service Entrance & Outside Wiring Design

How this test works

Frequently Asked Questions

Is this Master Electrician Practice Test 13 – Service Entrance & Outside Wiring Design free?

How do I qualify for the Master Electrician exam?

What is covered on the Master Electrician exam?

How is the Master exam different from the Journeyman exam?

Before You Start

Topics in This Test

Electrician Reviews

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Master Electrician Practice Test 13 – Service Entrance & Outside Wiring Design — Question List

Question 1: NEC 230.70(A) requires the service disconnecting means to be located:

Question 2: When a service has more than one disconnecting means, NEC 230.72(A) requires them to be:

Question 3: Under NEC 230.79(A), a service disconnect supplying a single branch circuit must have a minimum rating of:

Question 4: For an installation not otherwise covered by NEC 230.79(A) through (C) — such as most commercial services — what is the minimum service disconnect rating required by 230.79(D)?

Question 5: NEC 230.85 requires one- and two-family dwellings to have an emergency disconnecting means that is:

Question 6: NEC 230.9(A) requires overhead service conductors to maintain what minimum clearance from windows, doors, and porches designed for human egress?

Question 7: Per NEC 230.54(C), the service head (weatherhead) on an overhead service must be located:

Question 8: NEC 230.54(F) requires what to be formed on individual overhead service-entrance conductors to prevent water from entering the service head?

Question 9: Per NEC Article 100, the "service point" is defined as:

Question 10: What is the key difference between a service drop and a service lateral, per NEC Article 100?

Question 11: A detached garage on the same property as a house, fed from the house's panel rather than directly from the utility, generally may receive how many feeders or branch circuits under NEC 225.30?

Question 12: NEC 225.31 requires each building or structure supplied by a feeder or branch circuit to have:

Question 13: NEC 225.32 requires the disconnecting means for an outside feeder or branch circuit to be located:

Question 14: NEC 225.18(1) requires overhead conductors at the electrical service entrance to a building, rated 150 volts to ground or less, to maintain what minimum vertical clearance above finished grade?

Question 15: NEC 230.42(A) requires service-entrance conductors to have an ampacity of not less than:

Question 16: NEC 230.66 requires service equipment to be:

Question 17: Which of the following is NOT a permitted wiring method for service-entrance conductors under NEC 230.43?

Question 18: Mirroring the six-disconnect rule for services in 230.71, NEC 225.33 permits how many disconnecting means for one set of feeder or branch-circuit conductors supplying a building?

Question 19: A single-family dwelling has a 100A service. What minimum ampacity must the service-drop conductors supplying that dwelling provide under NEC 230.31(B)?

Question 20: Per NEC 200.6, a grounded (neutral) service conductor may be identified by which color or marking?

Question 21: NEC 230.2 generally limits a building to a single service, but recognizes exceptions. Which of the following is a recognized exception?

Question 22: NEC 230.28 requires a service mast used to support service-drop conductors to be:

Question 23: A homeowner runs an underground feeder from the main dwelling panel to power a detached workshop on the same lot. Which NEC article primarily governs this installation?

Question 24: Which statement correctly distinguishes a "service" from a "feeder" under the NEC?

Question 25: Underground service-lateral conductors installed by the utility are typically NOT subject to which set of NEC requirements?

Key NEC References for This Test

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