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MASTER NEC 2023

Master Electrician Practice Test 14 – Air-Conditioning & Refrigeration Equipment

This is Master Electrician Practice Test 14 — Air-Conditioning & Refrigeration Equipment, covering NEC Article 440, the hermetic refrigerant motor-compressor rules that trip up even experienced electricians because they replace the usual Article 430 horsepower tables with nameplate current values. The test has 25 multiple-choice questions on rated-load current, branch-circuit selection current, disconnect and conductor sizing formulas, overload protection, multimotor equipment nameplate marking (MCA/MOCP), and room air conditioner rules. 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

Air-Conditioning & Refrigeration

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 22 questions. Skip tough ones and come back.

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Review your answers

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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

Use of rated-load current (RLC) instead of horsepower for sizing (NEC 440.6(A))
Disconnect rating — 115% of the nameplate RLC or BCSC, whichever is greater (NEC 440.12)
Disconnect location exception — lockable in place instead of within sight (NEC 440.14)
Branch-circuit protective device maximum sizing — 175%/225% of RLC or BCSC (NEC 440.22(A))
Single motor-compressor conductor sizing — 125% of RLC or BCSC (NEC 440.32)
Overload protection based on marked rated-load current (NEC 440.52)
Multimotor/combination-load equipment nameplate — MCA and MOCP (NEC 440.4(B))
Using marked MCA/MOCP values directly instead of calculating per motor
GFCI protection for room air conditioners (NEC 440.65)
Article 440 equipment must also comply with Article 430 except as modified (NEC 440.3)
Branch-circuit selection current (BCSC) definition and use
Attachment plug and receptacle as the disconnecting means for room A/C units (NEC 440.63)
Why hermetic compressors use RLC instead of horsepower-based tables
Calculating equipment without a marked MCA/MOCP — fall back to Article 430
Scope of Article 440 — hermetic refrigerant motor-compressor equipment
Overload sizing fallback when no RLC is marked
225% exception when 175% is insufficient to permit starting (NEC 440.22(A))
Disconnect rating calculation from a marked RLC value
Minimum circuit ampacity (MCA) — conductor sizing rule
Maximum overcurrent protection (MOCP) — a ceiling, not a fixed size
Room air conditioners — Part VII-specific rules distinct from central equipment
Hermetic refrigerant motor-compressor definition

Tip: On any Article 440 question, first ask "does the nameplate give me a rated-load current (RLC) or a branch-circuit selection current (BCSC)?" If BCSC is marked, it always wins over RLC for every downstream calculation — conductors, disconnect, and OCPD.

Questions

45 min

Time

70%

Pass

Timer starts immediately. Progress is auto-saved.

Master Electrician Practice Test 14 – Air-Conditioning & Refrigeration Equipment — Question List

Question 1: Under NEC 440.6(A), what value is used to determine ampacity, disconnect, and overcurrent protection sizing for a hermetic refrigerant motor-compressor, instead of the horsepower rating used in Article 430?

The horsepower rating from NEC Table 430.250
The marked rated-load current (RLC), or branch-circuit selection current if marked
The locked-rotor current only
The nameplate voltage only

NEC Reference: NEC 440.6(A)

Question 2: Under NEC 440.12, the disconnecting means for a hermetic motor-compressor must be rated at not less than what percentage of the nameplate rated-load current (or branch-circuit selection current, whichever is greater)?

100%
115%
125%
175%

NEC Reference: NEC 440.12

Question 3: NEC 440.14 generally requires the A/C equipment disconnect to be within sight of the equipment. Under what condition may it instead be located out of sight?

Never — it must always be within sight, no exceptions
If it can be individually locked in the open position
If the equipment is under 5A
If the homeowner agrees in writing

NEC Reference: NEC 440.14

Question 4: Under NEC 440.22(A), the branch-circuit short-circuit and ground-fault protective device for a single motor-compressor is generally limited to what maximum percentage of the RLC or BCSC?

115%
125%
175%
300%

NEC Reference: NEC 440.22(A)

Question 5: A hermetic compressor has a marked rated-load current of 24A and no branch-circuit selection current marked. Per NEC 440.32, what minimum ampacity must the branch-circuit conductors have?

24 amperes
27.6 amperes
30 amperes
42 amperes

NEC Reference: NEC 440.32

Question 6: Overload protection for a hermetic refrigerant motor-compressor under NEC 440.52 is primarily sized based on:

The marked rated-load current
The horsepower rating only
The service disconnect rating
The building's total connected load

NEC Reference: NEC 440.52

Question 7: A packaged rooftop unit contains a compressor plus several fan motors under one enclosure. Per NEC 440.4(B), the manufacturer's nameplate for this multimotor/combination-load equipment must show:

Only the total horsepower of all motors combined
Minimum Circuit Ampacity (MCA) and Maximum Overcurrent Protection (MOCP)
Only the refrigerant charge weight
Only the manufacturer's warranty period

NEC Reference: NEC 440.4(B)

Question 8: When a multimotor unit's nameplate shows a Minimum Circuit Ampacity (MCA) of 26.4A, how should the installer size the branch-circuit conductors?

Ignore the MCA and calculate each motor individually per Article 430
Size conductors to at least the marked MCA value
Always round the MCA down to the nearest 10A
Use the MCA only for the disconnect, not the conductors

NEC Reference: NEC 440.4(B)/440.35

Question 9: NEC 440.65 requires GFCI protection for which type of equipment?

Central rooftop packaged units only
Room air conditioner receptacle circuits, 125V–250V single-phase
Only three-phase compressors
Walk-in refrigeration units only

NEC Reference: NEC 440.65

Question 10: NEC 440.3 states that air-conditioning and refrigeration equipment covered by Article 440 must also comply with which other article, except as modified by Article 440?

Article 250 — Grounding and Bonding
Article 430 — Motors, Motor Circuits, and Controllers
Article 700 — Emergency Systems
Article 800 — Communications Circuits

NEC Reference: NEC 440.3

Question 11: A compressor nameplate shows a rated-load current (RLC) of 18A and a branch-circuit selection current (BCSC) of 22A. Which value governs the conductor, disconnect, and OCPD sizing calculations?

The 18A rated-load current, always
The 22A branch-circuit selection current
The average of the two values
Whichever value is smaller

NEC Reference: NEC 440.6(A)/440.4(A)

Question 12: Why does NEC Article 440 use a marked rated-load current instead of a horsepower-based table for hermetic compressors, unlike Article 430 for open motors?

Because horsepower ratings are banned by the NEC
Because the sealed, refrigerant-immersed motor's real current draw is not predictable from horsepower alone
Because hermetic compressors never draw starting current
Because Article 430 only applies to three-phase motors

NEC Reference: NEC 440.6(A)

Question 13: Multimotor equipment is installed without a marked MCA or MOCP on its nameplate, but each individual motor has its own separate nameplate. How should the installer size the circuit?

Guess a reasonable wire size with no calculation
Calculate the circuit per Article 430's rules for multiple motors, using each motor's individual nameplate
Refuse to install the equipment — it is a code violation to lack MCA/MOCP
Use only the largest motor's nameplate and ignore the rest

NEC Reference: NEC 440.4(B)/Article 430

Question 14: NEC Article 440 primarily covers equipment that includes:

Hermetic refrigerant motor-compressors and the equipment built around them
Only communications equipment
Only fire alarm systems
Only swimming pool pumps

NEC Reference: NEC 440.1

Question 15: If a compressor's nameplate does not mark a rated-load current at all (an older or non-hermetic unit), how is the equipment sized?

It cannot legally be installed under any circumstances
It is sized using the standard Article 430 horsepower-based provisions
It defaults to a flat 20A circuit regardless of size
It is exempt from all NEC requirements

NEC Reference: NEC 440.6

Question 16: A hermetic compressor's 175% branch-circuit OCPD calculation does not correspond to a standard fuse or breaker size, and the compressor fails to start reliably at that rating. What does NEC 440.22(A) allow?

No increase is ever permitted — 175% is an absolute maximum
Increase to the next standard size, up to a maximum of 225% of RLC/BCSC
Replace the OCPD with a non-standard custom-rated fuse only
Bypass overcurrent protection entirely for that circuit

NEC Reference: NEC 440.22(A) Exception

Question 17: For a cord-and-plug-connected room air conditioner, NEC 440.63 permits which of the following to serve as the required disconnecting means?

The attachment plug and receptacle
A separate 60A safety switch, always
The main service disconnect only
No disconnect is permitted for cord-and-plug equipment

NEC Reference: NEC 440.63

Question 18: A hermetic compressor has a marked RLC of 20A. Applying NEC 440.12, what is the minimum ampere rating the disconnecting means must carry?

20 amperes
23 amperes
25 amperes
35 amperes

NEC Reference: NEC 440.12

Question 19: The Minimum Circuit Ampacity (MCA) marked on a multimotor A/C nameplate is best described as:

A minimum floor for conductor ampacity — conductors must be at or above it
The exact wire size that must be used, with no larger substitution allowed
A recommendation only, with no code force
The maximum current the unit can ever draw

NEC Reference: NEC 440.4(B)

Question 20: The Maximum Overcurrent Protection (MOCP) value marked on a multimotor A/C nameplate is best described as:

A maximum ceiling for the OCPD rating — it must not be exceeded
The exact OCPD size that must be used, with no smaller size allowed
The minimum wire size for the branch circuit
A voltage rating, not a current rating

NEC Reference: NEC 440.4(B)

Question 21: Room air conditioners in NEC Article 440 Part VII are distinguished from central/packaged equipment in Parts III–V primarily because they are:

Always three-phase, unlike central equipment
Cord-and-plug-connected, factory-assembled units
Never permitted in dwelling units
Exempt from all Article 440 requirements

NEC Reference: NEC Article 440, Part VII

Question 22: Per NEC Article 100, a "hermetic refrigerant motor-compressor" is best defined as:

A compressor driven by a belt from an external open motor
A compressor and motor combined in one sealed housing, motor operating in the refrigerant atmosphere
Any motor larger than 5 horsepower
A motor used only for exhaust fans

NEC Reference: NEC Article 100

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 14 – Air-Conditioning & Refrigeration Equipment

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 14 – Air-Conditioning & Refrigeration Equipment

How this test works

Frequently Asked Questions

Is this Master Electrician Practice Test 14 – Air-Conditioning & Refrigeration Equipment 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 14 – Air-Conditioning & Refrigeration Equipment — Question List

Question 1: Under NEC 440.6(A), what value is used to determine ampacity, disconnect, and overcurrent protection sizing for a hermetic refrigerant motor-compressor, instead of the horsepower rating used in Article 430?

Question 2: Under NEC 440.12, the disconnecting means for a hermetic motor-compressor must be rated at not less than what percentage of the nameplate rated-load current (or branch-circuit selection current, whichever is greater)?

Question 3: NEC 440.14 generally requires the A/C equipment disconnect to be within sight of the equipment. Under what condition may it instead be located out of sight?

Question 4: Under NEC 440.22(A), the branch-circuit short-circuit and ground-fault protective device for a single motor-compressor is generally limited to what maximum percentage of the RLC or BCSC?

Question 5: A hermetic compressor has a marked rated-load current of 24A and no branch-circuit selection current marked. Per NEC 440.32, what minimum ampacity must the branch-circuit conductors have?

Question 6: Overload protection for a hermetic refrigerant motor-compressor under NEC 440.52 is primarily sized based on:

Question 7: A packaged rooftop unit contains a compressor plus several fan motors under one enclosure. Per NEC 440.4(B), the manufacturer's nameplate for this multimotor/combination-load equipment must show:

Question 8: When a multimotor unit's nameplate shows a Minimum Circuit Ampacity (MCA) of 26.4A, how should the installer size the branch-circuit conductors?

Question 9: NEC 440.65 requires GFCI protection for which type of equipment?

Question 10: NEC 440.3 states that air-conditioning and refrigeration equipment covered by Article 440 must also comply with which other article, except as modified by Article 440?

Question 11: A compressor nameplate shows a rated-load current (RLC) of 18A and a branch-circuit selection current (BCSC) of 22A. Which value governs the conductor, disconnect, and OCPD sizing calculations?

Question 12: Why does NEC Article 440 use a marked rated-load current instead of a horsepower-based table for hermetic compressors, unlike Article 430 for open motors?

Question 13: Multimotor equipment is installed without a marked MCA or MOCP on its nameplate, but each individual motor has its own separate nameplate. How should the installer size the circuit?

Question 14: NEC Article 440 primarily covers equipment that includes:

Question 15: If a compressor's nameplate does not mark a rated-load current at all (an older or non-hermetic unit), how is the equipment sized?

Question 16: A hermetic compressor's 175% branch-circuit OCPD calculation does not correspond to a standard fuse or breaker size, and the compressor fails to start reliably at that rating. What does NEC 440.22(A) allow?

Question 17: For a cord-and-plug-connected room air conditioner, NEC 440.63 permits which of the following to serve as the required disconnecting means?

Question 18: A hermetic compressor has a marked RLC of 20A. Applying NEC 440.12, what is the minimum ampere rating the disconnecting means must carry?

Question 19: The Minimum Circuit Ampacity (MCA) marked on a multimotor A/C nameplate is best described as:

Question 20: The Maximum Overcurrent Protection (MOCP) value marked on a multimotor A/C nameplate is best described as:

Question 21: Room air conditioners in NEC Article 440 Part VII are distinguished from central/packaged equipment in Parts III–V primarily because they are:

Question 22: Per NEC Article 100, a "hermetic refrigerant motor-compressor" is best defined as:

Key NEC References for This Test

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