Exam Cheat Sheet · Quick Reference
South Carolina Electrician
South 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
80
Passing score
70%
Exam time
300 min
Administered by
PSI Services Contractor
Format
Reference materials allowed
South Carolina State Portion 80 questions
General Electrical Knowledge
9 Q · 11%
Ohm's law and DC circuit calculationsAC circuit theory: impedance, reactance, and power factorElectrical units and fundamental quantities (voltage, current, resistance, capacitance, inductance)Three-phase and single-phase power relationshipsNEC definitions and code terminologyElectrical testing instruments and measurement methodsHarmonics: causes, effects, and mitigationConductor properties, types, and insulation classifications
Service, Feeders, and Branch Circuits
9 Q · 11%
Branch-circuit ratings, types, and voltage limitationsGFCI and AFCI protection requirements by location and occupancyService conductor clearances, sizing, and installation requirementsFeeder and service load calculations including demand factorsGrounding and bonding of services, feeders, and branch circuitsOvercurrent protection of conductors and standard ampere ratingsMultiwire branch circuit requirements and disconnecting meansConductor identification for grounded, equipment grounding, and ungrounded conductors
Grounding and Bonding
9 Q · 11%
Grounding electrode system and types of grounding electrodesEquipment grounding conductors and effective ground-fault current pathMain bonding jumper and system bonding jumper requirementsGrounding of service-supplied AC systemsGrounding of separately derived AC systemsBonding of electrical equipment and conductive materialsSurge-protective device (SPD) grounding and bonding connectionsPermitted and prohibited connection methods for grounding and bonding conductors
Conductors and Cables
9 Q · 11%
Conductor insulation types, temperature ratings, and applications (THHN, THWN, RHW, XHHW, etc.)Ampacity determination and adjustment factors for conductors and cablesConductor sizing, AWG/kcmil designations, and minimum size requirementsConductor identification and marking requirementsNonmetallic-sheathed cable (Types NM and NMC) uses, installation, and supportMetal-clad cable (Type MC) and armored cable (Type AC) uses and installationUnderground cable types (UF, USE, direct burial) and installation requirementsSpecialty cable types (MI, TC, SE, medium voltage MV) uses and construction
Raceways and Boxes
9 Q · 11%
Conduit fill calculations and conductor fill percentages (Chapter 9 Table 1 and Annex C)Securing and supporting requirements for each raceway type (spacing and fastening distances)Uses permitted and uses not permitted for each raceway type by location and environmentBend requirements — number per run, minimum radius, and field-bending methodsBox fill calculations for outlet, device, and junction boxes (Article 314)Pull box and junction box sizing for conductors 4 AWG and larger (straight and angle pulls)Cabinet, cutout box, and meter socket enclosure installation requirements (Article 312)Grounding and bonding of metallic raceways and boxes
Special Occupancies and Equipment
2 Q · 2%
Hazardous location classification — Class I, II, and III Divisions and ZonesWiring methods and sealing requirements in hazardous locationsHealth care facility wiring — patient care spaces, grounding, and essential electrical systemsSwimming pools, fountains, and similar installations — GFCI, bonding, and clearancesSpecial occupancies — commercial garages, aircraft hangars, motor fuel dispensing, and bulk storage plantsEmergency systems — power sources, wiring, and transfer equipmentElevators, escalators, and similar equipment — wiring, disconnects, and GFCI requirementsRecreational vehicles, mobile homes, and marinas — wiring and power supply requirements
Electrical Power
7 Q · 9%
Overcurrent protection devices and ratings (fuses, circuit breakers) for conductors and equipmentGrounding and bonding requirements for AC systems and service equipmentElectrical services: overhead and underground conductor clearances and installation requirementsTransformers: types, ratings, overcurrent protection, and installation requirementsGenerators: ratings, overcurrent protection, conductor ampacity, and marking requirementsEmergency, legally required standby, and optional standby power systemsElectrical power distribution systems: series, parallel, and three-phase circuit configurationsOvervoltage and surge protection devices (SPDs and surge arresters)
Motors
7 Q · 9%
Motor branch-circuit conductor sizing and ampacity requirementsMotor overload protection (types, ratings, and selection)Motor branch-circuit short-circuit and ground-fault protective device ratings (Table 430.52)Motor disconnecting means requirementsMotor controller marking and ratingsMotor nameplate markings and locked-rotor code lettersAdjustable-speed drive systems for motorsHermetic refrigerant motor-compressor circuit requirements (Article 440)
Low Voltage
2 Q · 2%
Class 1, Class 2, and Class 3 circuit classifications and power source requirementsWiring methods and cable types for Class 2 and Class 3 circuits (CL2, CL3, PLTC, plenum, riser)Separation requirements between low-voltage circuits and power/light conductorsFire alarm circuit types: non-power-limited (NPLFA) and power-limited (PLFA) wiring and cable requirementsLow-voltage lighting systems (Article 411): voltage limits, isolation, and installation requirementsLow-voltage suspended ceiling power distribution systems (Article 393): listing, connectors, and overcurrent protectionInstrumentation Tray Cable (Type ITC): permitted uses, ampacity, and overcurrent protectionCircuits operating at less than 50 volts (Article 720): conductor sizing, receptacle ratings, and workmanship
Lighting
5 Q · 6%
Luminaire installation requirements by location (wet, damp, corrosive, closets, bathrooms, show windows)Luminaire types and classification (incandescent, fluorescent, HID, LED, low-voltage)Luminaire support and mounting methods (outlet boxes, suspended ceilings, poles, trees)Grounding of luminaires and lighting equipmentRecessed luminaire requirements (clearances, thermal protection, Type IC vs. non-IC, wiring)Lampholders and lampholder installation requirementsBallasts and auxiliary equipment for electric-discharge and LED luminaires (thermal protection, disconnecting means)Branch-circuit voltage limitations and wiring requirements for lighting loads
Illuminated Signs
2 Q · 2%
Listing and labeling requirements for signs, outline lighting, and retrofit kitsRequired branch circuits and ratings for sign installationsDisconnecting means location and requirements for signs and outline lightingGrounding and bonding of sign equipment and metal partsEnclosure requirements for signs and outline lighting systemsNeon secondary-circuit wiring requirements (1000V or less and over 1000V)Transformers, electronic power supplies, and Class 2 power sources for signsMarking requirements for signs, retrofit kits, and retrofitted illumination systems
Fire Detection and Alarm Systems
2 Q · 2%
Types of initiating devices (manual fire alarm boxes, heat detectors, smoke detectors, flame detectors, supervisory switches)Heat detector classification, temperature ratings, and spacing requirementsSmoke detector placement, spacing, and coverage concepts (total, partial, selective, nonrequired)Notification appliance requirements (audible, visual, and tactile) including sound pressure levels and temporal patternsFire alarm circuit types and pathway class designations (Class A, B, N, X) under NEC Article 760 and NFPA 72 Chapter 12Power supply requirements and wiring methods for non-power-limited and power-limited fire alarm circuitsInspection, testing, and maintenance requirements and frequencies for fire alarm system componentsSupervising station alarm systems (central station, proprietary, and remote station) and signal transmission requirements
Safety Information
8 Q · 10%
Electrical hazard recognition and guarding of live parts (OSHA 1926 Subpart K)Ground-fault circuit interrupter (GFCI) and assured equipment grounding conductor program requirementsPersonal protective equipment selection, use, and employer payment obligationsElectrical protective equipment classes and testing (rubber insulating gloves, blankets, sleeves)Lockout/tagout and deenergizing lines and equipment for employee protectionConfined space entry procedures, atmospheric testing, and permit requirementsSC 811 excavator responsibilities, locate request procedures, and underground facility damage preventionFirst aid, medical services, and emergency response requirements on construction sites
Key Distinctions
OverloadvsShort circuit / 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, OverloadSurge 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 ArresterInvertervsRectifier
An inverter changes dc to ac, while a rectifier performs the opposite conversion (ac to dc); a transformer only changes voltage levels within the same current type.
NEC 2020 Article 100 — Definitions, InverterExternally operablevsDead front / enclosed / guarded
Externally operable means capable of being operated without exposing the operator to contact with live parts; 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)Plug fuses rated 15 A or lessvsPlug fuses of higher ampere rating
Plug fuses of 15-ampere and lower rating must be identified by a hexagonal configuration of the window, cap, or other prominent part to distinguish them from higher-rated fuses.
NEC 2020 Section 240.50(C)NEC Chapter 8 (communications systems)vsNEC Chapters 1 through 7
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 90.3Informational notes / explanatory materialvsCode requirements
Informational notes are included for informational purposes only and are not enforceable as requirements of the Code.
NEC 2020 Section 90.5(C)Dwelling-unit kitchen countertop receptaclesvsCommercial (other than dwelling) kitchen receptacles
Dwelling-unit countertop receptacles require both GFCI (210.8(A)(6)) and AFCI (210.12(A)) protection and must be supplied by the required 20-ampere small-appliance branch circuits, while 125–250-volt receptacles in non-dwelling kitchens or areas with a sink and permanent food-prep/cooking provisions (single-phase, 150 V or less to ground, 50 A or less) require GFCI protection for personnel.
NEC 2020 Section 210.8(A)(6) and 210.12(A)Feeder disconnect minimums for one/two-circuit and other installationsvsFeeder disconnect minimum for a one-family dwelling
Not more than two 2-wire branch circuits require a disconnect rated at least 30 amperes and 'all others' at least 60 amperes, while a one-family dwelling supplied by a feeder from another building requires at least 100 amperes, 3-wire.
NEC 2020 Section 225.39(B)Optional dwelling calculation, 220.82(B)vsExisting dwelling additional-load calculation, 220.83(A)
Under 220.82(B) the general calculated load is not less than 100% of the first 10 kVA plus 40% of the remainder (and 220.82(A) applies only where a single 120/240-V or 208Y/120-V 3-wire set of service or feeder conductors has an ampacity of 100 or greater), while 220.83(A), used where no additional air-conditioning or electric space-heating equipment is added, takes 100% of the first 8 kVA plus 40% of the remainder.
NEC 2020 Section 220.82(B)Overhead open-conductor clearance, pedestrians onlyvsOverhead open-conductor clearance over truck-traffic areas
For spans not over 1000 volts, the clearance above finished grade is 3.0 m (10 ft) where voltage does not exceed 150 volts to ground and the area is accessible to pedestrians only, versus 5.5 m (18 ft) over public streets, alleys, roads, parking areas subject to truck traffic, and non-residential driveways.
NEC 2020 Section 225.18(1)Wye-start, delta-run motor conductorsvsPart-winding connected motor conductors
Conductors between controller and motor must be at least 72% of motor full-load current for wye-start/delta-run (58% × 1.25) versus at least 62.5% for part-winding connection (50% × 1.25).
NEC 2020 Section 430.22(C)Grounded conductor at a separate building fed by a feedervsGrounded conductor at the service
At a separate building or structure supplied by a feeder, an equipment grounding conductor is run with the supply conductors and any installed grounded conductor shall NOT be connected to the equipment grounding conductor or grounding electrode(s) there; a grounded conductor also shall not be reconnected to ground on the load side of the service disconnecting means except as otherwise permitted.
NEC 2020 Section 250.32(B)(1)Key Terms
Continuous load NEC 2020 Article 100
A load where the maximum current is expected to continue for 3 hours or more (continuous loads typically require conductors and devices rated at 125% of the continuous load current).
Ampacity NEC 2020 Article 100 — Definitions
The maximum current, in amperes, that a conductor can carry continuously under the conditions of use without exceeding its temperature rating.
Available fault current (fault current available) 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.
Interrupting rating (110.9) NEC 2020 Section 110.9
Equipment intended to interrupt current at fault levels must have an interrupting rating at nominal circuit voltage at least equal to the current available at the line terminals of the equipment.
Demand factor 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.
Neutral point NEC 2020 Article 100 — Definitions, Neutral Point
The common point on a wye connection in a polyphase system, the midpoint of 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; the vectorial sum of nominal voltages from all other phases there is zero potential.
Nonlinear load 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.
Inverse time (circuit breaker) 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.
Uninterruptible power supply (UPS) 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.
Effective ground-fault current path (250.4(A)(5)) NEC 2020 Section 250.4(A)(5)
The intentionally constructed low-impedance path for fault current; the earth shall not be considered as an effective ground-fault current path.
Supply-side bonding jumper (250.30(A)(2)) NEC 2020 Section 250.30(A)(2)
A jumper installed with the circuit conductors from the source enclosure of a separately derived system to the first disconnecting means enclosure when the two are in separate enclosures.
Main bonding jumper / system bonding jumper screw (250.28(B)) NEC 2020 Section 250.28(B)
Where the bonding jumper is a screw only, the screw must be identified with a green finish that is visible with the screw installed.
Supplemental grounding electrode (250.53(A)(2)) NEC 2020 Section 250.53(A)(2)
An additional electrode of a type in 250.52(A)(2) through (A)(8) required to supplement a single rod, pipe, or plate electrode, unless that single electrode has a resistance to earth of 25 ohms or less.
High-impedance grounded neutral system (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 when all specified conditions are met.
Objectionable current (250.6(B)) NEC 2020 Section 250.6(B)
Current resulting from multiple grounding connections; where 250.4(A)(5) or (B)(4) is still met, one permitted remedy is to discontinue one or more but not all of such grounding connections.
Competent person (OSHA 29 CFR 1926.32(f)) OSHA 1926 CFR 29, Page 31
One who is capable of identifying existing and predictable hazards in the surroundings or working conditions that are unsanitary, hazardous, or dangerous to employees, and who has authorization to take prompt corrective measures to eliminate them (no degree, years of experience, or certificate is specified).
Type S flexible cord (Table 400.4) NEC 2020 Table 400.4
A hard service, 600-volt cord with thermoset insulation and thermoset outer covering, suitable for pendant or portable use in damp locations with an extra-hard usage rating.
Formulas to Know
Minimum service-entrance / feeder conductor ampacity with continuous and noncontinuous loads
Ampacity ≥ noncontinuous load + 125% of continuous load; e.g., 150 A + (80 A × 1.25) = 250 A (230.42(A)(1)); feeder: (100 A × 1.25) + 30 A = 155 A (215.2(A)(1))Motor branch-circuit conductor ampacity (single continuous-duty motor)
Ampacity ≥ 125% × motor FLC from Table 430.250; e.g., 50 HP, 480 V, 3-phase = 65 A → 65 × 1.25 = 81.25 AFeeder ampacity for multiple motors (430.24)
Ampacity ≥ (125% × FLC of highest-rated motor) + sum of FLCs of all other motors; e.g., (1.25 × 65 A) + 40 A = 121.25 A; three 15.2 A motors: (1.25 × 15.2) + 15.2 + 15.2 = 49.4 ASeparate motor overload device maximum trip setting (430.32(A)(1))
115% × nameplate FLC for standard motors; up to 125% × nameplate FLC where marked service factor ≥ 1.15 or temperature rise ≤ 40°C (e.g., 14 A × 1.25 = 17.5 A; 28 A × 1.25 = 35 A; 30 A → 34.5 A or 37.5 A maximum, not a range); if insufficient, 430.32(C) permits incremental increases up to 140%Motor branch-circuit short-circuit and ground-fault protection maximums (Table 430.52)
AC polyphase motor (other than wound-rotor): nontime-delay fuse = 300% × FLC (52 A × 3 = 156 A; 65 A × 3 = 195 A → next standard 200 A per 430.52(C)(1) Ex. 1 and 240.6(A)); dual-element time-delay fuse = 175% × FLC (65 A × 1.75 = 113.75 A → next standard size up); single-phase inverse time breaker = 250% × FLC (50 A × 2.5 = 125 A → next standard 150 A if motor won't start); inverse time breaker may be increased for starting but not over 400% × FLC for FLC of 100 A or less (60 A × 4 = 240 A)Hermetic refrigerant motor-compressor conductors and OCPD
Conductors ≥ 125% × RLA (440.32): 30 A × 1.25 = 37.5 A; 20 A × 1.25 = 25 A. OCPD ≤ 175% × RLA (440.22(A)): 30 A × 1.75 = 52.5 A → 50 A standard size (the 2020 NEC has no next-higher-size exception here); may be increased only if starting current cannot be carried, to a maximum 225% of RLAGenerator output conductor ampacity (445.13)
Ampacity ≥ 115% × generator nameplate current rating; 80 A × 1.15 = 92 A minimum; 200 A × 1.15 = 230 A minimumOne-family dwelling service conductor 83% rule (310.12(A))
For a service rated 100 through 400 A supplying the entire load of a one-family dwelling on a single-phase 120/240-V system, service conductor ampacity may be ≥ 83% of the service rating; 200 A × 0.83 = 166 AConductor ampacity adjustment and rooftop temperature adder
10–20 current-carrying conductors in a raceway: adjustment factor 50% (Table 310.15(C)(1)); 10 AWG THHN 90°C = 40 A × 0.50 = 20 A. Rooftop raceway/cable in direct sunlight less than 23 mm (7/8 in.) above the roof: add 33°C (60°F) to the outdoor temperature before applying correction factors; 40°C + 33°C = 73°C (104°F + 60°F = 164°F)Minimum box dimension for an angle pull (314.28(A)(2))
Distance from raceway entry to opposite wall ≥ (6 × trade size of largest raceway) + sum of diameters of all other raceway entries on the same wall; (6 × 2) + 1 = 13 in.