Exam Cheat Sheet · Quick Reference
Mississippi - NASCLA ACCREDITED TRADE EXAMINATION FOR ELECTRICAL CONTRACTORS
Mississippi · 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
100
Passing score
75%
Exam time
270 min
Administered by
PSI Services Contractor
Format
Reference materials allowed
Mississippi State Portion 100 questions
Project Design & Management
8 Q · 8%
Electrical load calculations and service sizingBlueprint and schematic reading for electrical systemsProject scheduling and sequencing of electrical workMaterial takeoffs and quantity estimationElectrical system design compliance with NEC requirementsJob cost estimating and biddingCoordination with other trades and project stakeholdersPermit and inspection processes for electrical projectsContract types and payment structures for electrical projects (lump sum, unit price, cost-plus, retainage)Risk management and insurance requirements for electrical contractors (builder's risk, liability, bonding)Subcontractor qualification, selection, and site coordination requirementsProject scheduling methods (bar chart, critical path method, calendar scheduling) for electrical work
+7 more
Safety
9 Q · 9%
Personal protective equipment (PPE) requirements for electrical workLockout/tagout procedures for electrical energy controlElectrical hazard identification and arc flash safetyOSHA regulations applicable to electrical contractorsSafe work practices for energized and de-energized electrical systemsLadder and scaffold safety for electrical installationsConfined space entry proceduresFire prevention and extinguisher use on job sitesEnergized electrical work permit requirements and documentationElectric shock physiology and effects of current on the human bodyElectrical safety program responsibilities of employers and employeesSafety-related maintenance of electrical equipment and protective devices
+7 more
Electrical Theory and Principles
11 Q · 11%
Ohm's Law and voltage, current, resistance relationshipsSeries and parallel circuit analysisPower and energy calculations (watts, kilowatts, horsepower conversions)AC vs DC fundamentals and waveform characteristicsCapacitance and inductance in AC circuitsPower factor and reactive power conceptsElectromagnetism and transformer principlesThree-phase power calculations and configurationsAtomic structure, electron theory, and conductor/insulator propertiesKirchhoff's Voltage and Current Laws applicationsImpedance calculations in AC circuits (Z from R, XL, and XC)Harmonic currents and nonlinear load effects on waveforms
+8 more
General Code Requirements
17 Q · 17%
NEC Article 90 purpose, scope, enforcement, and arrangement of the CodeArticle 100 definitions used across the Code (accessible, readily accessible, approved, listed, labeled, bonding, grounded, etc.)110.2-110.3 approval, listing, and use of equipment per instructions110.4-110.7 voltages, conductor material, insulation integrity110.9-110.10 interrupting rating and short-circuit current ratings110.11-110.13 deteriorating agents, workmanship, mounting and cooling of equipment110.14 electrical connections, terminal temperature ratings, and torque110.15-110.16 high-leg marking and arc-flash hazard warning labels110.21-110.25 equipment marking, disconnect identification, available fault current marking, lockable disconnecting means110.26 working space depth, width, height, entrance, and dedicated equipment space (600 V and below)110.27-110.28 guarding of live parts and enclosure types110.30-110.34 working space and guarding for installations over 1000 volts
+3 more
Wiring and Protection
17 Q · 17%
Grounding and bonding requirements for electrical systemsOvercurrent protection sizing and device selectionBranch circuit ratings and conductor ampacityGround fault circuit interrupter (GFCI) protection requirementsArc fault circuit interrupter (AFCI) protection requirementsSurge protection device requirementsConductor insulation types and wiring methodsService entrance and feeder protection requirementsVoltage drop calculations for branch circuits and feedersAmpacity correction and adjustment factors for conductorsLoad calculations and demand factors for feeders and servicesMultiwire branch circuit requirements and neutral conductor sizing
+5 more
Wiring Methods & Materials
16 Q · 16%
Cable and conduit types and their permitted usesConduit fill calculations and conductor allowancesInstallation requirements for NM, MC, and AC cableRaceway installation and support requirementsWiring methods in specific occupancies and environmentsConductor sizing, insulation types, and temperature ratingsProtection requirements for wiring methods (physical damage, wet locations)Boxes, fittings, and enclosure requirements for wiring systemsUnderground installation requirements including minimum cover depths and direct-burial methodsConductor grouping, continuity, and same-circuit requirements in racewaysConduit bending techniques including 90-degree, offset, saddle, and back-to-back bendsCorrosion protection and material suitability requirements for raceways and enclosures
+5 more
General Equipment Use
13 Q · 13%
Safe use and handling of electrical tools and equipmentEquipment ratings and selection for electrical applicationsGrounding and bonding of electrical equipmentOvercurrent protection requirements for equipmentEquipment installation and mounting requirementsDisconnecting means for electrical equipmentEquipment listing and labeling requirementsWorking clearances and access around electrical equipmentMotor full-load current tables and nameplate data interpretationMotor overload protection sizing and placementMotor branch-circuit conductor sizing requirementsTransformer sizing, turns ratios, and primary/secondary current calculations
+6 more
Special Occupancies, Special Equipment, and Special Conditions
8 Q · 8%
Hazardous locations classification (Class I, II, III; Divisions 1 and 2)Wiring methods and equipment permitted in hazardous locationsHealth care facilities electrical requirements (hospitals, nursing homes)Places of assembly occupancy wiring requirementsAgricultural buildings and structures electrical installationsElectric signs, outline lighting, and associated wiringSwimming pools, fountains, and similar installationsTemporary installations and construction site wiring requirementsSolar PV system disconnecting means and rapid shutdown requirementsEmergency and legally required standby system power sources and transfer equipmentEquipotential bonding requirements for swimming pools and similar installationsZone 0, 1, and 2 hazardous location classification and protection techniques
+4 more
Communication Systems
1 Q · 1%
Installation requirements for communication wiring and cablesArticle 800 telephone and telegraph systemsCoaxial cable installation and groundingNetwork-powered broadband communications systemsOptical fiber cables and racewaysBonding and grounding of communication systemsSeparation from power conductorsCommunication circuit protectors and surge protectionCable listing requirements and cable type substitutions (CMP, CMR, CMG, CMX, CATV, BM, BL types)Fire and smoke rating requirements for plenum, riser, and general-purpose cablesAbandoned cable removal requirementsOverhead aerial wire clearances and routing requirements above roofs and between buildings
+5 more
Key Distinctions
Unit price estimating methodvsQuantity take-off method
The unit price method bundles all cost factors (labor, materials, equipment, subcontractors) into a single price for the entire task, while the quantity take-off method estimates each component individually.
NASCLA Contractors Guide, Bidding and Estimating chapter — Other Methods of Estimating sectionMediationvsArbitration / judge
In mediation the parties themselves set the conditions of any agreement with dialogue facilitated by an independent third-party mediator, whereas an arbitrator or judge sets forth the terms of the agreement.
NASCLA Contractors Guide, Contract Management chapter — Alternative Dispute Resolution sectionCapacitors at service equipment or panelsvsCapacitors at the individual loads
Capacitors at service equipment/panels are primarily intended to reduce utility power factor penalties, while capacitors at the individual loads reduce circuit current, voltage drop, and wire power losses.
Mike Holt's Understanding Electrical Theory for NEC Applications, Page 153Energized work permit Part I (requester)vsEnergized work permit Part II (electrically qualified persons)
In NFPA 70E 2024 Annex J Figure J.1, the requester completes Part I — circuit/equipment description, job location, work to be done, and justification for not de-energizing — while the qualified persons complete Part II items such as risk assessment results, safe work practices, and access restriction means.
NFPA 70E 2024, Informative Annex J, Figure J.1Multifamily dwellingvsTwo-family dwelling
Per NEC 2023 Article 100, a multifamily dwelling contains three or more dwelling units; a building consisting solely of two dwelling units is a two-family dwelling.
NEC 2023 Article 100 — definition of Dwelling, MultifamilyUnderground cover in 'all locations not specified' (Table 300.5(A))vsUnderground cover under a one- and two-family dwelling driveway
In locations not otherwise specified, direct-buried cables require 600 mm (24 in.) cover and RMC/IMC require 150 mm (6 in.), but under a one- and two-family dwelling driveway or dwelling-related outdoor parking area RMC requires 450 mm (18 in.), the same as direct-burial cable in that location.
NEC 2023 Table 300.5(A)BuswayvsCable tray system / lighting track / multioutlet assembly
Article 100 defines busway itself as a raceway (metal enclosure with factory-mounted conductors), while a cable tray system is a structural support system, lighting track is an assembly that supports and energizes luminaires, and a multioutlet assembly contains a raceway but is not itself defined as one.
NEC 2023 Article 100 — Definitions of Raceway, Busway, Cable Tray System, Lighting Track, and Multioutlet AssemblyType MV (medium voltage) cablevsPortable power feeder cable
Type MV is a solid dielectric insulated cable rated 2001 volts up to and including 35,000 volts nominal, whereas the 2001 to 25,000 volt range belongs to the separate definition of portable power feeder cable.
NEC 2023 Article 100 — Definition of 'Cable, Medium Voltage (Type MV)'Overhead service clearance over public streets/alleys/truck-traffic areasvsOverhead service clearance over residential property and driveways
Per 230.24(B), service conductors not over 1000 V need a minimum 5.5 m (18 ft) over public streets, alleys, roads, truck-traffic parking areas and nonresidential driveways, but only 3.7 m (12 ft) over residential property and driveways and commercial areas not subject to truck traffic where voltage does not exceed 300 volts to ground.
NEC 2023 Section 230.24(B)Elevator raceway conductor fill (620.33)vsGeneral wiring fill, Chapter 9 Table 1
For elevator installations the sum of the cross-sectional area of individual conductors shall not exceed 50 percent of the raceway interior area, a special provision that differs from the standard Chapter 9, Table 1 fill percentages used in general wiring.
NEC 2023 Section 620.33Motor branch OCPD at the Table 430.52(C)(1) maximumvsIncreased rating under 430.52(C)(1) Exception No. 2
Table 430.52(C)(1) permits an inverse time circuit breaker up to 250% of motor full-load current, and if the motor will not start the Exception permits an increase that shall in no case exceed 400% of FLC for motors of 100 A or less (300% for motors above 100 A) — not simply the next standard size.
NEC Section 430.52(C)(1), Exception No. 2; Table 430.52(C)(1)EGC sized from the instantaneous-trip circuit breaker ratingvsEGC sized per 250.122(D)(2)
Where branch-circuit short-circuit and ground-fault protection is an instantaneous-trip circuit breaker or motor short-circuit protector, the wire-type EGC is sized using the maximum permitted rating of a dual-element time-delay fuse per 430.52(C)(1)(a), not the rating of the instantaneous-trip device.
NEC 2023 Section 250.122(D)(2)Bar chart / calendar schedulingvsScheduling that shows interdependencies
A main weakness shared by bar chart and calendar scheduling is that they do not show interdependencies of activities, so a delay in one task does not show its impact on other tasks.
NASCLA Contractors Guide (14th ed.), Chapter 8 — Bar Chart Scheduling sectionKey Terms
Cable, Medium Voltage (Type MV) NEC 2023 Article 100 — Definition of 'Cable, Medium Voltage (Type MV)'
A single or multiconductor solid dielectric insulated cable rated 2001 volts up to and including 35,000 volts, nominal (NEC 2023 Article 100).
Busway NEC 2023 Article 100 — Definitions of Raceway, Busway, Cable Tray System, Lighting Track, and Multioutlet Assembly
A raceway consisting of a metal enclosure containing factory-mounted bare or insulated conductors (NEC 2023 Article 100).
Splash pad NEC 2023 Article 100 — definition of Splash Pad
A fountain intended for recreational use by pedestrians and designed to contain no more than 25 mm (1 in.) of water depth, excluding showers intended for hygienic rinsing prior to use of a pool, spa, or other water feature (NEC 2023 Article 100).
Dwelling, Multifamily NEC 2023 Article 100 — definition of Dwelling, Multifamily
A building that contains three or more dwelling units (NEC 2023 Article 100).
Pull point (for bend limits) NEC 2023 Section 358.24(B)
A point such as a conduit body that ends a run segment; EMT bends are limited to 360° between pull points, so each section between pull points may have up to 360° of bends (NEC 2026/2023 358.24(B); NEC 2020/2017 358.26).
Array boundary (PV rapid shutdown) NEC 2023 Section 690.12(B)
For rapid shutdown purposes the array boundary is 305 mm (1 ft) from the array in all directions; controlled conductors outside this boundary and more than 1 m (3 ft) from the array, or inside a building, are limited to not more than 30 volts within 30 seconds of rapid shutdown initiation (NEC 690.12(B)).
Optional calculation for a dwelling unit NEC 2023 Section 220.82(A)
Permitted where the total connected load is served by a single 120/240-volt or 208Y/120-volt set of 3-wire service or feeder conductors with an ampacity of 100 or greater (NEC 220.82(A)).
Class I, Division 2 area around an outdoor fuel dispenser NEC 2023 Table 514.3(B)(1)
The area up to 450 mm (18 in.) above grade level, extending 6 m (20 ft) horizontally in all directions from the dispenser enclosure (NEC Table 514.3(B)(1)).
Unclassified area in a commercial garage (ventilated) NEC 2023 Table 511.3(C)
The area up to 450 mm (18 in.) above floor level is unclassified where mechanical ventilation provides at least 0.3 m³/min/m² (1 cfm/ft²) of floor area with exhaust taken within 300 mm (12 in.) of floor level; without adequate ventilation that same area is Class I, Division 2 (NEC Table 511.3(C)).
Lockout/tagout device standardization 29 CFR 1910 - OSHA Occupational Safety and Health Standards (General Industry), § 1910.147(c)(5)(ii)(B), Page 505
Lockout and tagout devices must be standardized within the facility in at least one of color, shape, or size, and tagout devices must additionally be standardized in print and format (29 CFR 1910.147(c)(5)(ii)(B)); attachment strength (unlocking strength of no less than 50 pounds) is a separate 'substantial' requirement.
Indefinite delivery indefinite quantity (IDIQ) contract A Guide to the Project Management Body of Knowledge (PMBOK Guide), Section 4.6.8, Page 191
A contract providing for an indefinite quantity of goods or services, with a stated lower and upper limit, within a fixed time period (PMBOK Guide 4.6.8).
Inland marine insurance NASCLA Contractors Guide (14th ed.), Chapter 3 — Inland Marine/Equipment Theft Insurance section
A type of property insurance that can be purchased for tools and equipment and provides coverage for goods in transit and projects under construction (an equipment floater is a type of inland marine insurance).
IRS Form W-9 NASCLA Contractors Guide (14th ed.), Chapter 12: Working with Subcontractors – Creating a Winning Partnership
The form a subcontractor should complete prior to starting work on the jobsite (Form W-4 is for employee withholding, 1099-NEC reports payments after the fact, SS-4 applies for an EIN).
Interior lighting alteration trigger (ASHRAE 90.1-2022) ANSI/ASHRAE/IES Standard 90.1-2022, Energy Standard for Sites and Buildings Except Low-Rise Residential Buildings (I-P), Pages 148-149 (Section 9.1.1.3.1)
An interior lighting alteration must comply with Section 9.2 when the total wattage of all new and retrofitted luminaires is greater than 2000 W; at 2000 W or less the space may instead meet LPA tables plus specified controls or reduce wattage at least 50% below the original (Section 9.1.1.3.1(a)).
Table 310.16 ampacity basis NEC 2023 Section 310.16
Ampacities in Table 310.16 are based on a 30°C (86°F) ambient temperature; other ambients require correction factors from Table 310.15(B)(1)(1).
kcmil / THHN designation Conductor sizing units (kcmil)
One kcmil equals 1,000 circular mils (sizes larger than 4/0 AWG are expressed in kcmil), and in THHN the T is thermoplastic insulation, HH is high heat resistance (90°C dry), and N is a nylon outer jacket.
Formulas to Know
Continuous load sizing — feeder/branch conductors and branch OCPD
Feeder conductor minimum ampacity = noncontinuous load + 125% of continuous load (215.2(A)(1)); example: 80 A + (60 A x 1.25) = 155 A. Branch-circuit OCPD rating shall not be less than 125% of the continuous load (210.20(A)); example: 16 A x 1.25 = 20 A.Motor branch-circuit conductor ampacity
Minimum ampacity = 125% of motor full-load current from the NEC motor FLC tables (430.22); example: 5 HP, 230 V, 1-phase = 28 A x 1.25 = 35 A.Motor feeder conductor ampacity (multiple motors)
Minimum ampacity = 125% of the largest motor FLC + sum of the FLCs of the other motors (430.24); examples: (1.25 x 65 A) + 40 A = 121.25 A; (1.25 x 15.2 A) + 15.2 A + 15.2 A = 49.4 A.Motor feeder overcurrent device maximum
Rating shall not be greater than the largest motor branch-circuit short-circuit/ground-fault device rating + sum of the FLCs of the other motors (430.62(A)); example: 90 A + 14 A + 10 A = 114 A, and since 114 A is not a standard size per 240.6(A), the next LOWER standard size (110 A) is selected.Motor branch-circuit short-circuit/ground-fault device maximum
Nontime delay fuse = 300% of FLC for AC polyphase motors, and where the result is not a standard size the next standard size up is permitted (430.52(C)(1) Ex. 1); example: 65 A x 3.00 = 195 A → 200 A. Inverse time CB = 250% of FLC, and if the motor fails to start the rating may be increased but shall in no case exceed 400% of FLC for motors 100 A or less (300% above 100 A); example: 50 A x 2.5 = 125 A, maximum 50 A x 4 = 200 A.Non-dwelling receptacle load demand factors
First 10 kVA at 100% + remainder over 10 kVA at 50% (Table 220.47); example: 18 kVA → 10,000 VA + (8,000 x 0.50 = 4,000 VA) = 14,000 VA.Junction box minimum dimension for an angle pull
Distance to the opposite wall = 6 x trade size of the largest raceway + sum of the diameters of all other raceway entries in the same row on the same wall (314.28(A)(2)); example: (6 x 3 in. = 18 in.) + 2 in. = 20 in.Dwelling general lighting, small-appliance and laundry load
General lighting = floor area x 3 VA/sq ft, plus 1,500 VA per small-appliance circuit, plus 1,500 VA per laundry circuit; examples: 2,000 sq ft + 2 SA + 1 laundry = 6,000 + 3,000 + 1,500 = 10,500 VA; 1,800 sq ft + 3 SA + 2 laundry = 5,400 + 4,500 + 3,000 = 12,900 VA; 1,200 sq ft unit = 8,100 VA each, x 4 units = 32,400 VA before demand factors.Retail (non-dwelling) general lighting plus receptacle outlets, before demand factors
Area x 1.9 VA/sq ft (NEC 2020 Table 220.12 / NEC 2023 Table 220.42(A) / NEC 2026 Table 120.42(A)) + 180 VA per receptacle outlet on one yoke (220.14(I); 120.14(I) in 2026); example: 3,500 x 1.9 = 6,650 VA + (20 x 180 = 3,600 VA) = 10,250 VA. The 1,500 VA per circuit figure applies only to dwelling small-appliance circuits, and 3 VA/sq ft was the NEC 2017 store unit load.Basic electrical theory calculations
Ohm's law: I = E / R (240 V / 48 ohms = 5 A). Terminal power loss: P = I² x R ((25 A)² x 0.20 ohm = 125 W). Three-phase power: P = √3 x V x I x cos θ. Inductive reactance: XL = 2πfL (not 2πfC). Series-parallel: RT = series R + parallel Rp, I = E / RT, branch current = voltage across bank ÷ branch resistance.