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MASTER NEC 2023

Master Electrician Practice Test 23 – Motors Deep Dive

This is Master Electrician Practice Test 23 — Motors Deep Dive, going past the basic conductor and overcurrent sizing rules to cover the parts of NEC Article 430 that trip people up on the master exam: which current value to use for which calculation, controller ratings, and multi-motor and multispeed situations. The test has 25 multiple-choice questions on Table full-load current vs. nameplate current, individual and shared disconnects, controller horsepower ratings, multispeed motors, and small-motor exceptions. 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

Motors Deep Dive

How this test works

Read each question carefully

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

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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

Table full-load current used for conductors, OCPD, and disconnect sizing (NEC 430.6(A)(1))
Nameplate current used specifically for overload protection sizing (NEC 430.6(A)(2))
Why the NEC keeps these two current values separate
Each motor generally needs its own individual disconnect (NEC 430.87)
Exception — one disconnect for coordinated controllers driving parts of a single machine (NEC 430.87)
Motor controller horsepower rating must not be less than the motor's rating (NEC 430.83(A)(1))
Exception — inverse-time breakers and molded-case switches as controllers (NEC 430.83)
Exception — small stationary motor controller options (NEC 430.83)
Multispeed motor conductor sizing — 125% of the winding's current (NEC 430.22(B))
Why multispeed motors use nameplate current instead of a single table value
Small stationary motor general-use snap switch disconnect exception (NEC 430.109)
Horsepower-rated switch as the standard motor disconnect (NEC 430.109)
Motor nameplate marking requirements (NEC 430.7)
Overload sizing — 125% vs. 115% of nameplate current based on service factor/temp rise (NEC 430.32)
Multiple small motors sharing one branch circuit (NEC 430.53)
Feeder sizing for multiple motors — 125% of the largest plus 100% of the rest (NEC 430.24)
Controller disconnect location — within sight of the controller (NEC 430.102(A))
Motor location — ventilation and maintenance access (NEC 430.14)
Applying Table FLC vs. nameplate current to the same motor
Scope of Article 430, Part VI — motor control circuits
Control circuit conductors need their own overcurrent protection
Torque motor controller rating exception
Scope of Article 430 overall
Why the exam tests the FLC/nameplate distinction so heavily
Worked calculation — branch-circuit conductor sizing from Table FLC

Tip: Whenever a motor question gives you two different current numbers — a Table value and a nameplate value — stop and ask what the question is actually sizing. Conductors, OCPDs, and disconnects use the Table value. Overload protection uses the nameplate value. That single distinction resolves most of the trickiest motor questions on the exam.

Questions

45 min

Time

70%

Pass

Timer starts immediately. Progress is auto-saved.

Master Electrician Practice Test 23 – Motors Deep Dive — Question List

Question 1: Under NEC 430.6(A)(1), what value is used to size branch-circuit conductors, overcurrent devices, and disconnects for a motor — the nameplate current or the Table 430.250 full-load current?

The nameplate current
The Table 430.250 full-load current
Whichever value is smaller
The average of the two values

NEC Reference: NEC 430.6(A)(1)

Question 2: Under NEC 430.6(A)(2), what value is used specifically to size a motor's overload (overload relay) protection?

The motor's actual nameplate current
The Table 430.250 value only
The service disconnect rating
The building's total connected load

NEC Reference: NEC 430.6(A)(2)

Question 3: Why does the NEC use two different current values for the same motor — a Table value for conductors/OCPDs and a nameplate value for overload protection?

Table values standardize infrastructure sizing; nameplate values protect the specific motor from real overload
There is no real reason — it is an arbitrary rule
The nameplate value is always larger, so it is used everywhere
Table values are only used for single-phase motors

NEC Reference: NEC 430.6

Question 4: As a general rule under NEC 430.87, how many disconnecting means does each motor require?

One individual disconnect per motor
One disconnect for the entire building, regardless of motor count
No disconnect is ever required for motors
Exactly two disconnects per motor

NEC Reference: NEC 430.87

Question 5: NEC 430.87 recognizes an exception allowing a single disconnecting means to serve more than one motor when:

A group of coordinated controllers drives several parts of a single machine
The motors are all the exact same horsepower
The motors are all single-phase
The building has fewer than 5 motors total

NEC Reference: NEC 430.87

Question 6: Under NEC 430.83(A)(1), a motor controller's horsepower rating must generally be:

Not less than the motor's horsepower rating
Exactly half the motor's horsepower rating
Irrelevant — controllers have no horsepower rating requirement
Always rated in amperes only, never horsepower

NEC Reference: NEC 430.83(A)(1)

Question 7: Which of the following devices is recognized by NEC 430.83 as a motor controller without needing a specific horsepower rating?

An inverse-time circuit breaker or molded-case switch rated in amperes
A residential light switch
A doorbell transformer
A GFCI receptacle

NEC Reference: NEC 430.83

Question 8: For a stationary motor rated 2 hp or less and 300V or less, NEC 430.83 permits the controller to be a general-use switch rated at not less than:

Twice (200%) the motor's full-load current
The motor's full-load current, with no margin
Half the motor's full-load current
125% of the motor's full-load current

NEC Reference: NEC 430.83

Question 9: A multispeed motor's low-speed winding has a nameplate current of 16A. Per NEC 430.22(B), what minimum ampacity is required for the branch-circuit conductors that carry only that winding's current?

16A
18.4A
20A
32A

NEC Reference: NEC 430.22(B)

Question 10: Why does NEC 430.22(B) require multispeed motor conductors to be sized from nameplate current instead of a single Table 430.250 value?

Because full-load current varies by speed/winding, and no single table value covers that
Because multispeed motors are exempt from all sizing rules
Because Table 430.250 only applies to three-phase motors
Because multispeed motors never draw more than 1A

NEC Reference: NEC 430.22(B)

Question 11: For a stationary motor of 2 hp or less and 300V or less, NEC 430.109 permits a general-use AC snap switch to serve as the disconnecting means if:

The motor's FLC does not exceed 80% of the switch's ampere rating
The motor is rated over 10 hp
The switch is unmarked and unlisted
The motor operates at 600V

NEC Reference: NEC 430.109

Question 12: Outside the small-motor exception, what type of disconnect does NEC 430.109 require for a typical motor circuit?

A listed motor-circuit switch rated in horsepower
A standard light switch with no special rating
No disconnect at all
A smoke detector interlock

NEC Reference: NEC 430.109

Question 13: Which of the following is required on a motor nameplate under NEC 430.7?

Horsepower, rated voltage, full-load current, frequency, and phase
Only the manufacturer's logo
Only the warranty period
Nothing — nameplates are optional

NEC Reference: NEC 430.7

Question 14: A motor has a marked service factor of 1.15. Under NEC 430.32, what percentage of its nameplate current is generally used to size its overload protection?

100%
115%
125%
175%

NEC Reference: NEC 430.32

Question 15: Under NEC 430.53, multiple small motors are permitted to share a single branch circuit only if certain conditions are met, including that each motor:

Has its own individual overload protection
Is rated at least 50 hp
Operates at 600V or higher
Has no overload protection of any kind

NEC Reference: NEC 430.53

Question 16: A feeder supplies three motors with full-load currents of 30A, 20A, and 12A. Per NEC 430.24, what current value is used to size that feeder?

62A
69.5A
75A
77.5A

NEC Reference: NEC 430.24

Question 17: NEC 430.102(A) requires the disconnecting means for a motor controller to be located:

Within sight of the controller
Anywhere in the building, with no visibility requirement
Only inside a locked electrical room
At least 500 ft from the controller

NEC Reference: NEC 430.102(A)

Question 18: NEC 430.14 requires a motor's location to allow for:

Adequate ventilation and access for maintenance
Complete enclosure with no airflow
Submersion in water at all times
No access requirement of any kind

NEC Reference: NEC 430.14

Question 19: A 10 hp, 230V, three-phase motor has a Table 430.250 full-load current of 28A, but its nameplate shows an actual full-load current of 26A. Which value governs conductor sizing, and which governs the overload relay setting?

Conductors use 28A (Table); overload relay uses 26A (nameplate)
Conductors use 26A (nameplate); overload relay uses 28A (Table)
Both use 28A only
Both use 26A only

NEC Reference: NEC 430.6

Question 20: NEC Article 430, Part VI specifically addresses which motor-related topic?

Motor control circuits
Swimming pool bonding
Service entrance conductors
Fire alarm circuits

NEC Reference: NEC Article 430, Part VI

Question 21: Motor control circuit conductors (the small wires running to a start/stop station, for example) generally need:

Their own overcurrent protection sized for the smaller control wire
No overcurrent protection of any kind, ever
The exact same OCPD size as the motor's branch circuit
A dedicated 400A breaker regardless of wire size

NEC Reference: NEC Article 430, Part VI

Question 22: For a torque motor, NEC 430.83 requires the controller to have a continuous-duty, full-load current rating not less than:

The motor's nameplate current rating
Half the motor's nameplate current rating
A fixed 15A regardless of motor size
There is no rating requirement for torque motor controllers

NEC Reference: NEC 430.83

Question 23: NEC Article 430 as a whole covers which of the following?

Motors, motor circuits, and motor controllers
Swimming pools and fountains
Communications cabling
Emergency lighting only

NEC Reference: NEC Article 430

Question 24: Why do master exams lean so heavily on the difference between Table full-load current and nameplate current for motors?

Because mixing up the two values is a common, real-world sizing mistake worth catching before licensing
Because the two values are actually always identical
Because Table values were removed from the 2023 NEC
Because overload protection is no longer required in current code

NEC Reference: NEC 430.6

Question 25: A single continuous-duty motor has a Table 430.250 full-load current of 34A. What minimum ampacity is required for its branch-circuit conductors under NEC 430.22?

34A
39.1A
42.5A
51A

NEC Reference: NEC 430.22

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 23 – Motors Deep Dive

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Frequently Asked Questions

Before You Start

Topics in This Test

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Key NEC References for This Test

Master Electrician Practice Test 23 – Motors Deep Dive

How this test works

Frequently Asked Questions

Is this Master Electrician Practice Test 23 – Motors Deep Dive 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 23 – Motors Deep Dive — Question List

Question 1: Under NEC 430.6(A)(1), what value is used to size branch-circuit conductors, overcurrent devices, and disconnects for a motor — the nameplate current or the Table 430.250 full-load current?

Question 2: Under NEC 430.6(A)(2), what value is used specifically to size a motor's overload (overload relay) protection?

Question 3: Why does the NEC use two different current values for the same motor — a Table value for conductors/OCPDs and a nameplate value for overload protection?

Question 4: As a general rule under NEC 430.87, how many disconnecting means does each motor require?

Question 5: NEC 430.87 recognizes an exception allowing a single disconnecting means to serve more than one motor when:

Question 6: Under NEC 430.83(A)(1), a motor controller's horsepower rating must generally be:

Question 7: Which of the following devices is recognized by NEC 430.83 as a motor controller without needing a specific horsepower rating?

Question 8: For a stationary motor rated 2 hp or less and 300V or less, NEC 430.83 permits the controller to be a general-use switch rated at not less than:

Question 9: A multispeed motor's low-speed winding has a nameplate current of 16A. Per NEC 430.22(B), what minimum ampacity is required for the branch-circuit conductors that carry only that winding's current?

Question 10: Why does NEC 430.22(B) require multispeed motor conductors to be sized from nameplate current instead of a single Table 430.250 value?

Question 11: For a stationary motor of 2 hp or less and 300V or less, NEC 430.109 permits a general-use AC snap switch to serve as the disconnecting means if:

Question 12: Outside the small-motor exception, what type of disconnect does NEC 430.109 require for a typical motor circuit?

Question 13: Which of the following is required on a motor nameplate under NEC 430.7?

Question 14: A motor has a marked service factor of 1.15. Under NEC 430.32, what percentage of its nameplate current is generally used to size its overload protection?

Question 15: Under NEC 430.53, multiple small motors are permitted to share a single branch circuit only if certain conditions are met, including that each motor:

Question 16: A feeder supplies three motors with full-load currents of 30A, 20A, and 12A. Per NEC 430.24, what current value is used to size that feeder?

Question 17: NEC 430.102(A) requires the disconnecting means for a motor controller to be located:

Question 18: NEC 430.14 requires a motor's location to allow for:

Question 19: A 10 hp, 230V, three-phase motor has a Table 430.250 full-load current of 28A, but its nameplate shows an actual full-load current of 26A. Which value governs conductor sizing, and which governs the overload relay setting?

Question 20: NEC Article 430, Part VI specifically addresses which motor-related topic?

Question 21: Motor control circuit conductors (the small wires running to a start/stop station, for example) generally need:

Question 22: For a torque motor, NEC 430.83 requires the controller to have a continuous-duty, full-load current rating not less than:

Question 23: NEC Article 430 as a whole covers which of the following?

Question 24: Why do master exams lean so heavily on the difference between Table full-load current and nameplate current for motors?

Question 25: A single continuous-duty motor has a Table 430.250 full-load current of 34A. What minimum ampacity is required for its branch-circuit conductors under NEC 430.22?

Key NEC References for This Test

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