Exam Cheat Sheet · Quick Reference

North Carolina Electrical Contractor - Fire Alarm/Low Voltage (SP-FA/LV)

North Carolina · PSI Services Contractor

Verified, not estimated. Every figure below is drawn from the official exam structure we maintain — question counts, passing standard and topic weighting. Practice questions are grounded in the source law with statute citations. We omit any figure we can't verify rather than guess at it.

Total questions

Passing score

70%

Exam time

180 min

Administered by

PSI Services Contractor

Format

Reference materials allowed

North Carolina State Portion 50 questions

Bonding and Grounding 4 Q · 8%

Systems and equipment requiring grounding and ground-fault protectionLocation of connection and required interconnectionsConductor identification and color codingBonding jumpersEquipment grounding conductorsLow-voltage specificationsBonding conductor connectionsTermination

Wiring Methods and Terminations 9 Q · 18%

Permitted applications and usagesCharacteristicsConduit and wireway fillPermitted applications and usagesCharacteristicsProtection from damageTraveling cables and controlsPermitted usages and ampacity ratingsCharacteristicsMiscellaneousOutdoors

Boxes and Fittings 3 Q · 6%

General informationSizing requirements

Motors and Control Wiring 3 Q · 6%

General informationSeparation of conductors

Load Calculations 4 Q · 8%

Conductor ampacity requirementsLow-voltage

General 6 Q · 12%

DefinitionsInstallation requirements

Laws, Rules, Basic Business Practices, and Practical Applications 21 Q · 42%

Electrical Contractors Licensing Law (General Statutes Chapter 87, Article 4)Board’s Rules for the Implementation of the Electrical Contractors Licensing Law (Title 21, North Carolina Administrative Code, Chapter 18B)NASCLA Contractors’ Guide to Business, Law and Project Management - North Carolina Electrical EditionNational Fire Alarm Code

Key Distinctions

OverloadvsFault (short circuit or ground fault)

An overload is operation of equipment in excess of normal, full-load rating that causes damage or dangerous overheating when it persists, while a fault such as a short circuit or ground fault is expressly not an overload.

NEC 2020 Article 100 — Definitions, Overload

Surge arrestervsSPD (surge-protective device)

A surge arrester limits surge voltages by discharging or bypassing surge current and prevents continued flow of follow current while remaining capable of repeating these functions, whereas an SPD limits transient voltages by diverting or limiting surge current.

NEC 2020 Article 100 — Definitions, Surge Arrester

InvertervsRectifier

An inverter is equipment that changes dc to ac; a rectifier performs the opposite function, changing ac to dc.

NEC 2020 Article 100 — Definitions, Inverter

Multi-criteria detector (NFPA 72, 3.3.66.12)vsMulti-sensor detector (NFPA 72, 3.3.66.13)

A multi-criteria detector has multiple sensors but is capable of generating only one alarm signal and carries a single listing establishing its primary function, while a multi-sensor detector can generate multiple alarm signals and carries listings for each sensing method employed.

NFPA 72 National Fire Alarm and Signaling Code, Chapter 3 — 3.3.66.12 Multi-Criteria Detector and 3.3.66.13 Multi-Sensor Detector

Master alarm box (NFPA 72, 3.3.12.4)vsAuxiliary alarm box (3.3.12.1) / publicly accessible alarm box (3.3.12.5)

A master alarm box is publicly accessible AND can also be operated by remote initiating devices or an auxiliary alarm system, while an auxiliary alarm box can only be operated from remote initiating devices or an auxiliary system and a publicly accessible alarm box houses only a manually operated transmitter.

NFPA 72 National Fire Alarm and Signaling Code, Chapter 3 — 3.3.12 Alarm Box (3.3.12.1, 3.3.12.4, 3.3.12.5)

Feeder disconnect for a one-family dwelling — 225.39(C)vsFeeder disconnect for all other installations — 225.39(D)

When the building supplied is a one-family dwelling the feeder disconnecting means must be rated not less than 100 amperes, 3-wire, while all other installations (such as a detached garage with more than two 2-wire branch circuits) require not less than 60 amperes.

NEC 2020 Section 225.39(C)

Type AC / Type NM cable bending radiusvsType MC cable (interlocked armor or corrugated sheath) bending radius

Type AC (320.24) and Types NM/NMC (334.24) require an inner-edge bend radius of not less than five times the cable diameter, while interlocked-armor or corrugated-sheath Type MC (330.24(B)) requires not less than seven times the external diameter of the metallic sheath.

NEC 2020 Section 320.24

NEC Chapter 8 (communications systems)vsNEC Chapters 1 through 7

Per 90.3, Chapter 8 is NOT subject to the requirements of Chapters 1 through 7 except where those requirements are specifically referenced in Chapter 8.

NEC 2020 Section 90.3

Informational notes / explanatory materialvsCode requirements

Per 90.5(C), explanatory material such as informational notes is included for informational purposes only and is not enforceable as a requirement of the Code.

NEC 2020 Section 90.5(C)

Externally operablevsDead front / enclosed / guarded

Externally operable means capable of being operated without exposing the operator to contact with live parts, while dead front means without live parts exposed on the operating side, enclosed means surrounded by a case or housing to prevent accidental contact, and guarded means covered or shielded to remove the likelihood of approach to a point of danger.

NEC 2020 Article 100 (Definitions, Part I — Externally Operable)

UPS used in place of separate power supply sources (NFPA 72, 10.6.4.1)vsEngine-driven / supervising station generators

A UPS replacing separate primary and secondary supplies must comply with NFPA 111 as Type O, Class 24, Level 1, whereas engine-driven generators for protected premises secondary power are Type 10, Class 24, Level 1, automatic-starting supervising station generators are Type 60, Class 24, Level 2, and manual-starting supervising station generators are Type M, Class 24, Level 2.

National Fire Alarm Code (NFPA 72), 10.6.4.1

C CorporationvsS Corporation

Per the NASCLA Summary of Business Legal Structures table, a C corporation allows an unlimited number of shareholders with no personal liability and is taxed at the corporate level with a further tax on dividends (double taxation), while an S corporation is limited to 100 shareholders and uses pass-through taxation.

NASCLA Contractors Guide, North Carolina Electrical (14th ed.), Chapter 2 — Summary of Business Legal Structures table

Key Terms

Continuous load (NEC Article 100) NEC 2020 Article 100

A load where the maximum current is expected to continue for 3 hours or more.

Overload (NEC Article 100) NEC 2020 Article 100 — Definitions, Overload

Operation of equipment in excess of normal, full-load rating that, when it persists for a sufficient length of time, would cause damage or dangerous overheating; a fault such as a short circuit or ground fault is not an overload.

Surge arrester (NEC Article 100) NEC 2020 Article 100 — Definitions, Surge Arrester

A protective device for limiting surge voltages by discharging or bypassing surge current that also prevents continued flow of follow current while remaining capable of repeating these functions.

Inverter (NEC Article 100) NEC 2020 Article 100 — Definitions, Inverter

Equipment that changes dc to ac.

Neutral point (NEC Article 100) NEC 2020 Article 100 — Definitions, Neutral Point

The common point on a wye connection in a polyphase system, or the midpoint on a single-phase 3-wire system, the midpoint of a single-phase portion of a 3-phase delta system, or the midpoint of a 3-wire dc system.

Demand factor (NEC Article 100) NEC 2020 Article 100 — Definitions, Demand Factor

The ratio of the maximum demand of a system, or part of a system, to the total connected load of that system or part under consideration.

Uninterruptible power supply (UPS) (NEC Article 100) NEC 2020 Article 100 — Definitions, Uninterruptible Power Supply

A power supply used to provide alternating current power to a load for some period of time in the event of a power failure.

Inverse time (circuit breaker) (NEC Article 100) NEC 2020 Article 100 — Definitions, Circuit Breaker (Inverse Time)

A qualifying term indicating that a delay is purposely introduced in the tripping action of the circuit breaker, which delay decreases as the magnitude of the current increases.

Nonlinear load (NEC Article 100) NEC 2020 Article 100 — Definitions, Nonlinear Load

A load where the wave shape of the steady-state current does not follow the wave shape of the applied voltage.

Available fault current (NEC Article 100) NEC 2020 Article 100 — Definitions, Fault Current Available (Available Fault Current)

The largest amount of current capable of being delivered at a point on the system during a short-circuit condition.

Externally operable (NEC Article 100) NEC 2020 Article 100 (Definitions, Part I — Externally Operable)

Capable of being operated without exposing the operator to contact with live parts.

Girder (NFPA 72, 3.3.37.2) NFPA 72 National Fire Alarm and Signaling Code, Chapter 3 — 3.3.37.2 Girder

A support member for joists that is a factor in determining the number and location of detectors (treated as a beam) only when the top of the girder is within 4 in. (100 mm) of the ceiling.

Master alarm box (NFPA 72, 3.3.12.4) NFPA 72 National Fire Alarm and Signaling Code, Chapter 3 — 3.3.12 Alarm Box (3.3.12.1, 3.3.12.4, 3.3.12.5)

A publicly accessible alarm box that can also be operated by one or more remote initiating devices or an auxiliary alarm system to send an alarm to the communications center.

Multi-criteria detector (NFPA 72, 3.3.66.12) NFPA 72 National Fire Alarm and Signaling Code, Chapter 3 — 3.3.66.12 Multi-Criteria Detector and 3.3.66.13 Multi-Sensor Detector

A device containing multiple sensors that separately respond to physical stimuli, whose outputs are mathematically evaluated, that is capable of generating only one alarm signal and carries a single listing establishing its primary function.

High-impedance grounded neutral system (NEC 250.36) NEC 2020 Section 250.36

A system in which a grounding impedance limits ground-fault current to a low value, permitted for 3-phase AC systems of 480 volts to 1000 volts provided all specified conditions are met.

Supply-side bonding jumper (NEC 250.30(A)(2)) NEC 2020 Section 250.30(A)(2)

The jumper that must be installed with the circuit conductors from the source enclosure of a separately derived system to the first disconnecting means enclosure when they are in separate enclosures.

Formulas to Know

83-percent rule for one-family dwelling service conductors (NEC 310.12(A), services rated 100 through 400 A supplying the entire load on a single-phase 120/240-V system)Minimum conductor ampacity = 0.83 × service rating; worked example: 200 A × 0.83 = 166 A

Table ampacity needed when a temperature correction factor also applies to the 83% dwelling feeder

Required table ampacity = (0.83 × service rating) ÷ correction factor; worked example: 200 × 0.83 = 166 A, then 166 ÷ 0.91 = 182.4 A ≈ 182 A

Ampacity adjustment for 10 to 20 current-carrying conductors in a raceway or cable (Table 310.15(C)(1))Adjusted ampacity = 50% × table ampacity; worked example: 10 AWG THHN copper at 90°C = 40 A, 40 × 0.50 = 20 A

Ampacity adjustment for 7 to 9 current-carrying conductors in a raceway or cable (Table 310.15(C)(1))

Adjusted ampacity = 70% × values from Table 310.16 through Table 310.19, as already adjusted for ambient temperature if necessary

Rooftop ambient temperature for raceways/cables in direct sunlight less than 23 mm (7/8 in.) above the roof (NEC 310.15(B)(2))

Ambient for correction factors = outdoor temperature + 33°C (60°F); worked example: 40°C + 33°C = 73°C (104°F + 60°F = 164°F)

Minimum box dimension for an angle pull (NEC 314.28(A)(2))

Distance to opposite wall = (6 × trade size of largest raceway) + sum of diameters of all other raceway entries on the same wall; worked example: (6 × 2) + 1 = 13 in.

Minimum bending radius, interlocked-armor or corrugated-sheath Type MC cable (NEC 330.24(B))Radius = 7 × external diameter of the metallic sheath; worked example: 7 × 25 mm = 175 mm (7 in.)

Minimum bending radius, Type AC cable and Types NM/NMC cable (NEC 320.24, 334.24)Inner-edge radius shall not be less than 5 × the diameter of the cable

Overcurrent protection for a Class 1 power-limited source other than a transformer (NEC 725.41(A)(2))

OCPD rating not more than (167% × source VA) ÷ rated voltage; worked example: 600 VA × 1.67 = 1002; 1002 ÷ 24 V = 41.75 A, so the next lower standard rating from 240.6(A), 40 A, must be used

Creditable years of primary experience (21 NCAC 18B .0202(a))

Creditable years = total credited primary hours ÷ 2,000 (2,000 hours = one creditable year); worked examples: 11,000 ÷ 2,000 = 5.5 years; (6,000 at 100% + 2,500 at 100%) = 8,500 ÷ 2,000 = 4.25 years

Start free practice Full study guide