Exam Cheat Sheet · Quick Reference

North Carolina Limited Electrical Contractor (L)

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

100

Passing score

70%

Exam time

360 min

Administered by

PSI Services Contractor

Format

Reference materials allowed

North Carolina State Portion 100 questions

Bonding and Grounding 10 Q · 10%

Systems and equipment requiring grounding and ground-fault protectionLocation of connection and required interconnectionsConductor identification and color codingBonding jumpersGrounding electrode conductorsEquipment grounding conductorsGrounding electrodesLow-voltage specificationsBonding conductor connectionsBonding/bonding gridTermination

Overcurrent Protection 9 Q · 9%

Location in circuitSizing requirementsCircuit breakersPlug and cartridge fusesEnclosures and locations

Wiring Methods and Terminations 10 Q · 10%

Permitted applications and usagesCharacteristicsConduit and wireway fillPermitted applications and usagesCharacteristicsProtection from damagePermitted usages and ampacity ratingsCharacteristicsMiscellaneousOutdoorsSwitchboards, panelboards, switches, and cabinetsSpecial conditions

Boxes and Fittings 8 Q · 8%

General informationSizing requirements

Service Entrance and Equipment 11 Q · 11%

Installation requirementsService equipmentGeneral sizing requirements

Motors and Control Wiring 7 Q · 7%

General informationBranch circuit and feeder ampacityOverload protectionShort-circuit and ground-fault protectionDisconnects/controllersSizeTypeLocationSeparation of conductors

Special Occupancies and Hazardous Locations 6 Q · 6%

Mobile homes and mobile home parksSwimming poolsUnderwater lighting fixtures

Load Calculations 11 Q · 11%

Branch circuitsTotal computed loadConductor ampacity requirementsLow-voltage

Appliances, Equipment, and Lighting 7 Q · 7%

Air conditionersResidential, commercial, and industrial equipmentLighting fixturesSpace heating equipment and boilersTransformers

General 3 Q · 3%

DefinitionsInstallation requirements

Laws, Rules, Basic Business Practices, and Practical Applications 18 Q · 18%

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 EditionLighting and Power Plans; Estimating and General KnowledgeNational Fire Alarm Code

Key Distinctions

EMT securing distance (general intervals)vsEMT securing distance (near terminations)

EMT must be fastened at intervals not exceeding 10 ft generally, but within 900 mm (3 ft) of each box, cabinet, conduit body, or other termination.

NEC, Section 358.30(A)

Circuits prohibited from being grounded (250.22)vsCircuits permitted but not required to be grounded (250.21(A))

NEC 250.22 absolutely prohibits grounding of certain circuits (e.g., crane circuits over combustible fibers in Class III locations), whereas 250.21(A) lists systems that are allowed to remain ungrounded but are not mandated to be so.

NEC Handbook, Sections 250.22 and 250.21(A)

Conductor ampacity rule — standard (240.4(C))vsConductor ampacity rule — supervised industrial over 800 A (240.91(B))

Under standard NEC rules a conductor's ampacity must equal or exceed 100% of the overcurrent device rating, but in supervised industrial installations with devices rated over 800 A and two specific conditions met, ampacity need only be 95% of the device rating.

NEC, Section 240.91(B)

System bonding jumper at source transformervsSystem bonding jumper at first disconnecting means

When the bonding jumper is at the source it connects the grounded conductor to the supply-side bonding jumper and the non-current-carrying metal enclosure; when it is at the first disconnect, the grounding electrode conductor must also be connected at that same disconnect point.

NEC, Section 250.30(A)(5)

Continuous load feeder sizingvsNoncontinuous load feeder sizing

Feeder conductors must have ampacity equal to noncontinuous load plus 125% of the continuous load; noncontinuous loads are counted at 100% with no adder.

NEC, Section 215.2(A)(1)(a)

One-family dwelling service disconnect minimum (230.79(C))vsTwo-2-wire-branch-circuit installation service disconnect minimum (230.79(B))

A one-family dwelling requires a service disconnect rated at least 100 amperes 3-wire, while an installation with no more than two 2-wire branch circuits requires only 30 amperes.

NEC, Section 230.79(C)

Edison-base fuseholders (240.51(B))vsType S fuse adapters (240.52–240.54)

Edison-base fuseholders are permitted only as replacements in existing installations with no evidence of overfusing or tampering; once overfusing is found, Type S adapters must be installed so only correctly rated Type S fuses can be used and cannot be removed or shunted.

NEC, Sections 240.51(B), 240.52, 240.53, and 240.54

Interrupting RatingvsFault Current

Interrupting Rating is the highest current at rated voltage a device is identified to interrupt under standard test conditions, whereas Fault Current is the actual current delivered at a point on the system during a short-circuit condition.

NEC, Article 100 — Definition of Interrupting Rating

Grounding electrode conductor to rod/pipe/plate electrode (250.66(A))vsGrounding electrode conductor to concrete-encased electrode

When connected solely to a rod, pipe, or plate electrode the GEC need not exceed 6 AWG copper; the concrete-encased electrode rule requires at least 20 ft of rebar but does not cap the GEC size under 250.66(A).

NEC, Section 250.66(A)

Luminaires in fountains — voltage limit (680.51(B))vsSubmersible pumps in fountains — voltage limit

Luminaires in permanently installed fountains must operate on supply circuits of 150 volts or less between conductors, whereas submersible pumps and other submersible equipment may operate at up to 300 volts between conductors.

NEC 2020, Section 680.51(B)

10-ft tap rule — conductor ampacity (240.21(B)(1))vs25-ft tap rule — conductor ampacity (240.21(B)(2))

Tap conductors not over 25 ft long must have ampacity of at least one-third the feeder overcurrent device rating; the 10-ft tap rule requires a higher fraction (at least one-tenth is not applicable here — NEC 240.21(B)(2) specifies one-third for 25 ft taps).

NEC, Section 240.21(B)(2)

Parallel conductors minimum size — service/feeder (310.10(G)(1))vsParallel grounded conductor minimum size in each raceway (250.24(C)(2))

Both rules set a floor of 1/0 AWG, but 310.10(G)(1) governs phase, neutral, or grounded circuit conductors connected in parallel, while 250.24(C)(2) specifically governs the grounded (neutral) service-entrance conductor run in parallel in each separate raceway or cable.

NEC 2020, Section 310.10(G)(1)

Key Terms

Overcurrent NEC, Article 100 — Definition of Overcurrent

Per NEC Article 100, any current in excess of the rated current of equipment or the ampacity of a conductor, which may result from overload, short circuit, or ground fault.

Interrupting Rating NEC, Article 100 — Definition of Interrupting Rating

Per NEC Article 100, the highest current at rated voltage that a device is identified to interrupt under standard test conditions.

Fault Current NEC, Article 100 — Definition of Fault Current

Per NEC Article 100, the current delivered at a point on the system during a short-circuit condition.

Default circuit breaker interrupting rating NEC 2020, Section 240.83(C)

Per NEC 240.83(C), a circuit breaker with no interrupting rating marked on it is assumed to have a rating of 5,000 amperes.

Concrete-encased grounding electrode requirement NEC, Section 250.52(A)(3)

Per NEC 250.52(A)(3), at least 20 ft of bare or zinc-galvanized steel rebar (½ in. minimum diameter) encased by at least 2 in. of concrete in direct contact with the earth is required.

Supplemental grounding electrode exemption NEC, Section 250.53(A)(2), Exception

Per NEC 250.53(A)(2) Exception, a supplemental electrode is not required when a single rod, pipe, or plate electrode has a resistance to earth of 25 ohms or less.

Series rating prohibition — motor circuits (240.86(C)) NEC 2020, Section 240.86(C)

Per NEC 240.86(C), series ratings shall not be used where motor circuits are connected between the two devices and the sum of motor full-load currents exceeds 1% of the interrupting rating of the lower-rated breaker.

Optional dwelling-unit load calculation general load NEC, Section 220.82(B)

Per NEC 220.82(B), the general calculated load is 100% of the first 10 kVA plus 40% of the remainder of the listed loads.

Hotel/motel overcurrent device accessibility exception NEC Handbook, Section 240.24(B)(2)

Per NEC 240.24(B)(2), where electric service and maintenance are under continuous building-management supervision, branch-circuit overcurrent devices for guest rooms without permanent cooking provisions may be accessible only to authorized management personnel.

Maximum disconnects per supply at separate structure NEC 2020, Section 225.33(A)

Per NEC 225.33(A), no more than six switches or six circuit breakers mounted in one enclosure or grouped in one location are permitted per supply at a separate building or structure.

Minimum conductor size (up to 2000 V) NEC 2020, Section 310.3(A)

Per NEC 310.3(A), conductors for voltage ratings up to and including 2000 volts shall be no smaller than 14 AWG copper or 12 AWG aluminum or copper-clad aluminum.

Main bonding jumper NEC 2020, Section 250.24(C)

Per NEC 250.24(C), a conductor that connects the grounded conductor(s) to each service disconnecting means enclosure in a grounded AC system operating at 1000 volts or less.

Metal underground water pipe grounding electrode NEC, Section 250.52(A)(1)

Per NEC 250.52(A)(1), a metal underground water pipe must be in direct contact with the earth for at least 10 ft to qualify as a grounding electrode.

Solder-only connection prohibition NEC, Section 250.8(A) and (B)

Per NEC 250.8(B), connection devices or fittings that depend solely on solder shall not be used for grounding and bonding connections.

Laundry branch circuit NEC, Section 210.11(C)(2)

Per NEC 210.11(C)(2), at least one 20-ampere branch circuit must be provided for laundry receptacles, and it shall have no other outlets.

Available fault current field marking (110.24(A)) NEC, Section 110.24(A)

Per NEC 110.24(A), service equipment in other than dwelling units must be legibly field-marked with the available fault current and the date the calculation was performed; the calculator's name is not required.

Formulas to Know

Feeder conductor ampacity — continuous + noncontinuous loadsMinimum ampacity = Noncontinuous load (A) + (Continuous load (A) × 1.25)

Conductor ampacity — supervised industrial, OCD > 800 AMinimum conductor ampacity = OCD rating (A) × 0.95

25-ft feeder tap conductor minimum ampacityTap conductor ampacity ≥ Feeder OCD rating (A) ÷ 3

Single cord-and-plug equipment max rating on 15/20 A branch circuitMax equipment rating = Branch-circuit rating (A) × 0.80

Optional dwelling-unit calculated loadTotal load = 100% × first 10 kVA + 40% × (total listed load − 10 kVA)

Multifamily dwelling optional method — demand loadDemand load = Total calculated load (kVA) × Demand factor (from NEC Table 220.84, e.g., 0.41 for 12–13 units)

Minimum bending radius — Types USE and SE cableMinimum bend radius = 5 × cable outside diameter

Equipment interrupting rating requirementRequired interrupting rating ≥ Available fault current at line terminals (A)

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