Master Electrician / Electrical Contractor License Exam (General) — Questions and Answers

Question 1: A 50-ampere branch circuit using copper conductors at 75°C rating requires a minimum conductor size of:

2 AWG
6 AWG (Correct answer)
8 AWG
4 AWG

Correct answer: 6 AWG

NEC Table 310.16 shows that 6 AWG copper at 75°C has an ampacity of 65 amperes, which is the minimum size for a 50-ampere circuit.

Question 2: Per NEC 220.12, what is the general lighting load in VA per square foot for a bank?

3.5 VA/sq ft (Correct answer)
5.0 VA/sq ft
2.0 VA/sq ft
1.0 VA/sq ft

Correct answer: 3.5 VA/sq ft

NEC Table 220.12 lists banks at 3.5 VA per square foot for general lighting load calculations.

Question 3: What is the function of an inductor in a circuit?

To store energy in an electric field.
To convert electrical energy to mechanical energy.
To resist changes in current and store energy in a magnetic field. (Correct answer)
To increase the resistance of the circuit.

Correct answer: To resist changes in current and store energy in a magnetic field.

An inductor is a passive electrical component that stores energy in a magnetic field when current flows through it. Its primary function is to oppose changes in the current flowing through it, a property known as inductance, which makes it useful for filtering, tuning, and energy storage in AC circuits.

Question 4: When performing a standard load calculation for a single-family dwelling per NEC Article 220, what is the general lighting load allowance per square foot?

2 VA per square foot
3 VA per square foot (Correct answer)
5 VA per square foot
4 VA per square foot

Correct answer: 3 VA per square foot

The NEC specifies a general lighting load of 3 VA per square foot for dwelling units.

Question 5: Per NEC 215.2, a feeder supplying a continuous load of 80 amperes and a non-continuous load of 20 amperes must have conductors with a minimum ampacity of:

120 amperes (Correct answer)
110 amperes
125 amperes
100 amperes

Correct answer: 120 amperes

80A × 125% + 20A × 100% = 100 + 20 = 120 amperes minimum conductor ampacity.

Question 6: What phenomenon occurs when the supply frequency matches a circuit's natural resonant frequency?

Impedance is minimized and current is maximized (series resonance) (Correct answer)
Current drops to near zero
Power factor drops to zero
Impedance is maximized and current is minimized

Correct answer: Impedance is minimized and current is maximized (series resonance)

At series resonance, XL and XC cancel, leaving minimum impedance (equal to R only), which results in maximum current flow in the circuit.

Question 7: Per NEC Article 680, what is the minimum burial depth for a direct-buried cable supplying a pool pump motor when not under a building or concrete?

18 inches (Correct answer)
12 inches
24 inches
6 inches

Correct answer: 18 inches

NEC 680.10 and Table 300.5 require a minimum cover of 18 inches for direct-buried UF cable supplying pool equipment when not under a building or concrete.

Question 8: What type of ground-fault protection is required for a 15-ampere, 125-volt receptacle installed outdoors at a commercial occupancy per NEC Article 210?

No special protection required
GFCI protection (Correct answer)
AFCI protection
Both GFCI and AFCI protection

Correct answer: GFCI protection

NEC 210.8(B) requires GFCI protection for 15- and 20-ampere, 125-volt receptacles installed outdoors at commercial occupancies.

Question 9: Service-entrance cable (Type SE) used as interior wiring must comply with the requirements of:

Article 310 only
Article 338 and applicable wiring method articles (Correct answer)
Article 230 only
Article 250

Correct answer: Article 338 and applicable wiring method articles

NEC 338.10(B) states that SE cable used as interior wiring must comply with Article 338 and the applicable portions of Article 334.

Question 10: The demand factor for the first 3,000 VA of a residential lighting load is:

50%
100% (Correct answer)
75%
35%

Correct answer: 100%

NEC Table 220.42 requires the first 3,000 VA of residential lighting load to be calculated at 100%.

Question 11: A 120V branch circuit supplies a 1,500W electric water heater. What is the minimum circuit ampere rating required per NEC Article 422?

15 amperes
25 amperes
30 amperes
20 amperes (Correct answer)

Correct answer: 20 amperes

A 1,500W load at 120V draws 12.5A, and since a fixed appliance requires 125% sizing, the minimum is 15.625A, requiring a 20A circuit.

Question 12: In a series RLC circuit at resonance, what is true about the impedance?

Resistance drops to zero
Inductive and capacitive reactances cancel, leaving only resistance (Correct answer)
Capacitive reactance dominates
Impedance is at its maximum value

Correct answer: Inductive and capacitive reactances cancel, leaving only resistance

At resonance, XL = XC so they cancel each other out, and impedance equals only the circuit resistance (minimum impedance).

Question 13: What happens to the total current in a parallel circuit when an additional branch is added?

Total current stays the same
Total current drops to zero
Total current decreases
Total current increases (Correct answer)

Correct answer: Total current increases

Adding a parallel branch provides an additional path for current flow, which increases the total circuit current.

Question 14: What is the primary purpose of workers' compensation insurance for an electrical contracting business?

To protect the business from customer lawsuits
To provide retirement benefits for long-term employees
To cover medical costs and lost wages for employees injured on the job (Correct answer)
To replace damaged tools and equipment

Correct answer: To cover medical costs and lost wages for employees injured on the job

Workers' compensation insurance covers employees' medical expenses and a portion of lost wages when they suffer work-related injuries or illnesses.

Question 15: When must conductors in a raceway be considered current-carrying for the purpose of conduit fill derating?

Equipment grounding conductors are counted when sized larger than 8 AWG
Neutral conductors on 3-wire, single-phase systems carry only unbalanced current and are not counted (Correct answer)
Neutral conductors are never counted
Always, regardless of circuit type

Correct answer: Neutral conductors on 3-wire, single-phase systems carry only unbalanced current and are not counted

NEC 310.15(E) excludes the neutral conductor of a 3-wire single-phase circuit from the count of current-carrying conductors because it only carries unbalanced load current.

Question 16: When service entrance conductors are installed in parallel, what is the minimum size permitted per NEC 310.10(G)?

2/0 AWG
3/0 AWG
4/0 AWG
1/0 AWG (Correct answer)

Correct answer: 1/0 AWG

NEC 310.10(G) requires that each parallel conductor be 1/0 AWG or larger.

Question 17: According to NEC Article 90, what is the primary purpose of the National Electrical Code?

The practical safeguarding of persons and property from hazards arising from the use of electricity. (Correct answer)
To guarantee the future expansion of electrical use in all installations.
To provide design specifications for efficient electrical systems.
To serve as an instruction manual for untrained persons.

Correct answer: The practical safeguarding of persons and property from hazards arising from the use of electricity.

NEC 90.1(A) explicitly states that the purpose of the code is the 'practical safeguarding of persons and property from hazards arising from the use of electricity.' It is not intended as a design manual or an instruction guide for those without proper training.

Question 18: A qualified electrical worker finds a conductor presumed de-energized. OSHA 1910.333 requires the worker to treat the conductor as energized until:

It has been tested and verified de-energized with a proper testing device (Correct answer)
A lockout tag is visible on the panel
A supervisor verbally confirms it is off
The circuit has been de-energized for at least 10 minutes

Correct answer: It has been tested and verified de-energized with a proper testing device

OSHA requires conductors to be tested and verified de-energized with an appropriate voltage-testing device before being treated as safe to touch.

Question 19: When performing a load calculation for a single-family dwelling, which four types of loads are specifically excluded from the 75% demand factor allowed for four or more fastened-in-place appliances under NEC 220.53?

Dishwasher, garbage disposal, trash compactor, and water heater.
Water heater, dishwasher, range hood, and microwave oven.
Space-heating equipment, clothes dryers, cooking equipment, and air-conditioning equipment. (Correct answer)
Well pump, attic fan, garage door opener, and central vacuum system.

Correct answer: Space-heating equipment, clothes dryers, cooking equipment, and air-conditioning equipment.

NEC 220.53 permits a 75% demand factor for four or more fastened-in-place appliances served by the same feeder or service. However, it explicitly lists four exceptions that have their own specific calculation methods and demand factors: space-heating equipment (220.51), clothes dryers (220.54), cooking equipment (220.55), and air-conditioning equipment. These loads must be calculated according to their own rules and cannot be grouped with other appliances under the 75% rule.

Question 20: A liquidated damages clause in a construction contract specifies that:

The owner pays a bonus for early completion
The contractor must purchase materials at a fixed price
The contractor is immune from delay-related claims
A predetermined daily penalty applies for each day the project is completed late (Correct answer)

Correct answer: A predetermined daily penalty applies for each day the project is completed late

Liquidated damages clauses pre-establish a daily dollar amount the contractor owes for each day of project delay beyond the completion date.

Question 21: Which method is acceptable for splicing conductors within an electrical junction box?

Electrical tape wrapped tightly around twisted wires
Wire connectors (wire nuts) rated for the conductors (Correct answer)
Soldering only with no mechanical connection
Heat-shrink tubing applied over loosely joined wires

Correct answer: Wire connectors (wire nuts) rated for the conductors

NEC 110.14 requires splices to be made with listed devices such as wire connectors (wire nuts) that provide both mechanical and electrical connection.

Question 22: Which NEC article governs services, including the number of service disconnects permitted?

NEC Article 230 (Correct answer)
NEC Article 240
NEC Article 215
NEC Article 225

Correct answer: NEC Article 230

NEC Article 230 covers services, including the rule that no more than six disconnecting means are permitted.

Question 23: A variable frequency drive (VFD) repeatedly faults on 'output phase loss.' The motor and cabling test good. Where should the electrician look next?

Ground fault in the motor cable shield
Output contactor or terminal connections between VFD and motor (Correct answer)
Control wiring signal integrity at the VFD input terminals
Input fuses or disconnect on the line side of the VFD

Correct answer: Output contactor or terminal connections between VFD and motor

If the motor and cable test good, the output phase loss fault usually points to a loose connection or failed output contactor between the VFD and motor.

Question 24: An electrical crew is tasked with installing underground conduit in a trench that is 6 feet deep. Per OSHA regulations for excavations (29 CFR 1926 Subpart P), what is required before any worker is permitted to enter the trench?

All workers entering the trench must be attached to a personal fall arrest system.
The trench must be at least 4 feet wide at the bottom to ensure stability.
A ladder or other safe means of egress must be placed every 50 feet of lateral travel.
A protective system, such as sloping, shoring, or a trench shield (trench box), must be in place. (Correct answer)

Correct answer: A protective system, such as sloping, shoring, or a trench shield (trench box), must be in place.

OSHA standard 1926.652 requires that workers in trenches 5 feet deep or more must be protected from cave-ins by an adequate protective system, unless the excavation is made entirely in stable rock. Since this trench is 6 feet deep, a protective system like shoring, sloping, or a trench box is mandatory. A means of egress is required every 25 feet (not 50) for trenches 4 feet or deeper.

Question 25: What happens to the total resistance when resistors are connected in parallel?

It is always less than the smallest resistor (Correct answer)
It increases beyond the largest resistor
It equals the average of all resistors
It equals the sum of all resistors

Correct answer: It is always less than the smallest resistor

In a parallel circuit, the total resistance is always less than the smallest individual resistor because current has multiple paths.

Question 26: When sizing a branch circuit for a 9,600W household electric range at 240V using NEC Table 220.55 Column C, what is the maximum demand load?

7,200 watts
9,600 watts
8,000 watts (Correct answer)
6,000 watts

Correct answer: 8,000 watts

NEC Table 220.55 Column C permits a maximum demand of 8,000 watts for a single household range rated up to 12 kW.

Question 27: What is the key distinction between 'accounts receivable' and 'accounts payable' in a contracting business?

Accounts receivable tracks material costs; accounts payable tracks labor costs
They are interchangeable terms for the same financial concept
Accounts receivable is money owed TO the business by customers; accounts payable is money the business OWES to suppliers and subcontractors (Correct answer)
Accounts receivable are future project bids; accounts payable are completed project invoices

Correct answer: Accounts receivable is money owed TO the business by customers; accounts payable is money the business OWES to suppliers and subcontractors

Accounts receivable represents money customers owe you for completed work, while accounts payable represents money you owe to your suppliers, subcontractors, and vendors.

Question 28: In a 208/120V three-phase, four-wire wye system, what is the voltage measured between any two phase conductors?

277V
240V
208V (Correct answer)
120V

Correct answer: 208V

In a wye-connected system with 120V phase-to-neutral, the line-to-line voltage is 120 × 1.732 = approximately 208V.

Question 29: An electrical contractor completes a commercial tenant fit-out but the property owner refuses to pay the final invoice. To secure their claim against the property itself, what is the contractor's most direct legal remedy?

File a lawsuit for breach of contract.
Report the owner to the local building department.
Initiate a claim against their general liability insurance.
File a mechanic's lien against the property. (Correct answer)

Correct answer: File a mechanic's lien against the property.

A mechanic's lien is a legal claim placed on real property by those who have provided labor or materials to improve it but have not been paid. It 'clouds' the property's title, making it difficult for the owner to sell or refinance until the debt is settled, which provides powerful leverage for payment. While a breach of contract lawsuit is a valid action, it does not directly encumber the property itself.

Question 30: A service calculation yields a total demand of 175 amperes for a single-family home. Per NEC 230.79, what is the minimum service size that must be installed?

175-ampere service
100-ampere service
150-ampere service
200-ampere service (Correct answer)

Correct answer: 200-ampere service

Because NEC 230.79 sets 100A as the minimum and 175A exceeds standard 150A panels, a 200A service is the next standard size that meets or exceeds 175A.

Question 31: According to NEC 501.15, in Class I, Division 1 hazardous locations, what type of conduit seal is required within 18 inches of an enclosure?

A conduit seal fitting filled with sealing compound (Correct answer)
A flexible conduit section
An expansion fitting
A drain-and-breather fitting

Correct answer: A conduit seal fitting filled with sealing compound

NEC 501.15(A)(1) requires a conduit seal fitting with sealing compound within 18 inches of any enclosure in Class I, Division 1 locations.

Question 32: What is the function of an overload relay in a motor control circuit?

To protect against short circuits in the feeder
To provide instantaneous trip on ground faults
To protect the motor from sustained overcurrent conditions (Correct answer)
To regulate motor speed under varying loads

Correct answer: To protect the motor from sustained overcurrent conditions

Overload relays are designed to protect motors from damage caused by sustained overcurrent conditions that exceed the motor's rated capacity.

Question 33: Which of the following is an acceptable method for bonding around a water meter to maintain grounding continuity?

Relying on the meter's internal metal components
Using a plastic fitting on one side of the meter
Wrapping the meter with electrical tape
Installing a bonding jumper across the meter (Correct answer)

Correct answer: Installing a bonding jumper across the meter

A bonding jumper must be installed around the water meter to ensure continuous grounding because meters can be removed for service.

Question 34: What is the purpose of a jogging (inching) circuit in a motor control system?

Reverse motor direction automatically
Monitor motor temperature and trip on overtemperature
Allow repeated brief starts without engaging the seal-in contact (Correct answer)
Reduce starting current by inserting resistance momentarily

Correct answer: Allow repeated brief starts without engaging the seal-in contact

A jog circuit energizes the contactor only while the jog button is held, bypassing the seal-in contact so the motor runs only briefly for positioning.

Question 35: When computing a service load for a multi-family dwelling with 20 units, what demand factor applies to the lighting load between 3,001 VA and 120,000 VA per NEC Table 220.42?

100%
50%
75%
35% (Correct answer)

Correct answer: 35%

NEC Table 220.42 applies a 35% demand factor to the portion of dwelling lighting load between 3,001 VA and 120,000 VA.

Question 36: Per NEC 220.60, when calculating feeder or service loads, which of the following is a noncoincident load?

Electric heating and air conditioning loads (Correct answer)
Service entrance conductors and feeders
Two motors operating simultaneously
Lighting and receptacle loads

Correct answer: Electric heating and air conditioning loads

NEC 220.60 permits using only the larger of noncoincident loads—such as heating and cooling—since both are unlikely to operate simultaneously.

Question 37: Under OSHA regulations, what is the minimum approach distance for an unqualified electrical worker near exposed energized parts operating at 50 kV?

25 feet
10 feet (Correct answer)
20 feet
15 feet

Correct answer: 10 feet

OSHA 29 CFR 1926.416 requires unqualified workers to maintain at least 10 feet from exposed energized parts at 50 kV.

Question 38: What is the calculated load for two 6 kW household ranges using NEC Table 220.55, Column C?

11 kW (Correct answer)
10 kW
9 kW
12 kW

Correct answer: 11 kW

NEC Table 220.55 Column C lists the demand for two ranges rated up to 12 kW each as 11 kW.

Question 39: What does OSHA require regarding the use of extension cords on construction sites under 29 CFR 1926.405?

Extension cords are prohibited entirely on construction sites
Extension cords may only be used indoors
Extension cords may be used as permanent wiring if rated for the load
Extension cords must be of the three-wire type and designed for hard or extra-hard usage (Correct answer)

Correct answer: Extension cords must be of the three-wire type and designed for hard or extra-hard usage

OSHA requires that extension cords used on construction sites be three-wire type and rated for hard or extra-hard usage to withstand jobsite conditions.

Question 40: An electrical contractor is calculating the general lighting and receptacle load for a 40,000 sq. ft. retail store. Using the unit load values from NEC Table 220.12 and the demand factors from Table 220.42, what is the calculated load?

120,000 VA
85,000 VA (Correct answer)
100,000 VA
60,000 VA

Correct answer: 85,000 VA

First, calculate the total connected lighting load. Per NEC Table 220.12, a retail store has a unit load of 3 VA per sq. ft. So, 40,000 sq. ft. x 3 VA/sq. ft. = 120,000 VA. Next, apply the demand factors from Table 220.42 for 'All Others'. The first 50,000 VA is calculated at 100% (50,000 VA). The remainder (120,000 VA - 50,000 VA = 70,000 VA) is calculated at 50% (70,000 VA * 0.50 = 35,000 VA). The total calculated load is 50,000 VA + 35,000 VA = 85,000 VA.

Question 41: When calculating feeder neutral load for a residential service, how is the unbalanced load between lines reduced per NEC 220.61?

The neutral is sized at 100% of the maximum unbalanced load
The portion of neutral load above 200A may be reduced by 70% (Correct answer)
The neutral load is reduced by 25% for all loads
The neutral load is always equal to the phase load

Correct answer: The portion of neutral load above 200A may be reduced by 70%

NEC 220.61(B)(1) permits the neutral load above 200A to be multiplied by 70% for further reduction.

Question 42: In a separately derived system such as a transformer, where must the bonding jumper be installed?

At the source of the separately derived system (Correct answer)
At any convenient point in the system
At the main service panel only
At the nearest subpanel downstream

Correct answer: At the source of the separately derived system

NEC 250.30(A)(1) requires the system bonding jumper to be installed at the source of the separately derived system.

Question 43: A motor nameplate shows 'Code G.' What does this indicate?

Insulation temperature class
Motor design letter (torque characteristic)
Locked-rotor kVA per horsepower range (5.6–6.29) (Correct answer)
Motor efficiency class

Correct answer: Locked-rotor kVA per horsepower range (5.6–6.29)

NEMA Code letters indicate locked-rotor kVA per horsepower; Code G corresponds to 5.6–6.29 kVA/hp, used to size fuses and breakers.

Question 44: Under NEC 358.30, EMT must be secured within how many inches of each outlet box, junction box, or other termination?

18 inches
36 inches
30 inches (Correct answer)
24 inches

Correct answer: 30 inches

NEC 358.30(A) requires EMT to be secured within 3 feet (36 inches) of each box or termination.

Question 45: What property of a material determines how well it conducts electricity?

Permeability
Permittivity
Resistivity (Correct answer)
Reluctance

Correct answer: Resistivity

Resistivity (ρ) is an intrinsic material property that determines electrical resistance; lower resistivity means better conductivity.

Question 46: A motor's nameplate insulation class 'F' has a maximum allowable temperature rise (by resistance method) of:

115°C (Correct answer)
140°C
105°C
80°C

Correct answer: 115°C

NEMA Class F insulation is rated for a maximum temperature rise of 115°C above a 40°C ambient (155°C total), per NEMA MG-1.

Question 47: Which form of contract dispute resolution is typically binding and conducted outside of court by a neutral third party?

Mediation
Litigation
Arbitration (Correct answer)
Negotiation

Correct answer: Arbitration

Arbitration is a binding dispute resolution process where a neutral arbitrator hears both sides and issues a final, enforceable decision.

Question 48: What is the main difference between alternating current (AC) and direct current (DC)?

There is no difference between AC and DC.
AC flows in one direction, while DC changes direction periodically.
AC is used in batteries, while DC is used in power lines.
DC flows in one direction, while AC changes direction periodically. (Correct answer)

Correct answer: DC flows in one direction, while AC changes direction periodically.

The main difference between alternating current (AC) and direct current (DC) lies in their direction of flow. DC flows in one constant direction, typically from a positive to a negative terminal, whereas AC periodically reverses its direction of flow and continuously changes its magnitude, which is standard for power grids.

Question 49: What motor starting method provides the highest starting torque per ampere of line current drawn?

Part-winding starting
Autotransformer reduced-voltage starting (Correct answer)
Wye-delta starting
Across-the-line (full voltage) starting

Correct answer: Autotransformer reduced-voltage starting

Autotransformer starters provide the best torque-per-amp ratio because they apply reduced voltage via transformer action, which is more efficient than wye-delta or part-winding methods.

Question 50: Which raceway system is specifically designed for use in corrosive environments such as chemical plants or wastewater treatment facilities?

EMT (Electrical Metallic Tubing)
Schedule 80 PVC conduit (Correct answer)
RMC (Rigid Metal Conduit)
Flexible metal conduit

Correct answer: Schedule 80 PVC conduit

Schedule 80 PVC conduit provides excellent resistance to corrosion from chemicals, moisture, and acids, making it ideal for corrosive industrial environments.

Question 51: When calculating the load for a commercial kitchen, the NEC allows which demand factor to be applied to electric cooking equipment?

A flat 50% demand factor for all cooking equipment
No demand factor; full nameplate load must be used
A 125% multiplier since cooking equipment is a continuous load
Demand factors from NEC Table 220.56 based on number of units (Correct answer)

Correct answer: Demand factors from NEC Table 220.56 based on number of units

NEC Table 220.56 provides demand factors for commercial cooking equipment, allowing load reduction based on the number of cooking units installed.

Question 52: When sizing a service for a building with multiple HVAC units, how are the hermetic refrigerant motor-compressor loads treated per NEC 440.6?

At 125% of the largest motor plus 100% of all others
At the rated-load current or branch-circuit selection current, whichever is greater (Correct answer)
At 75% of nameplate current
At 80% of full-load current

Correct answer: At the rated-load current or branch-circuit selection current, whichever is greater

NEC 440.6 requires using the rated-load current or branch-circuit selection current (whichever is larger) as the load for each hermetic compressor.

Question 53: What is 'skin effect' in AC conductors?

Insulation breakdown due to high voltage
Corrosion of the conductor surface over time
Tendency of AC current to flow near the outer surface of a conductor (Correct answer)
Heat generated at conductor terminations

Correct answer: Tendency of AC current to flow near the outer surface of a conductor

Skin effect causes high-frequency AC current to concentrate near the conductor's outer surface, effectively reducing the usable cross-sectional area and increasing resistance.

Question 54: For an optional method dwelling unit calculation per NEC 220.82, what is the base load applied to the first 10 kVA of total connected load?

100% (Correct answer)
75%
40%
80%

Correct answer: 100%

Under the optional method in NEC 220.82, the first 10 kVA of general loads is taken at 100%.

Question 55: Which wiring method is required when installing conductors in a corrosive chemical storage area?

Rigid nonmetallic conduit (PVC) (Correct answer)
Type AC cable
Type NM cable
EMT with set-screw fittings

Correct answer: Rigid nonmetallic conduit (PVC)

NEC 300.6 and Article 352 allow rigid nonmetallic conduit (PVC) in corrosive environments where metallic raceways would be damaged.

Question 56: A 480V, 3-phase motor draws 28A at full load. Per NEC, the minimum branch circuit conductor ampacity before applying any derating is:

35A (Correct answer)
28A
42A
49A

Correct answer: 35A

NEC 430.22 requires branch circuit conductors to be sized at 125% of the motor's full-load current (28A × 1.25 = 35A).

Question 57: An electrician is performing a continuity test on a 3-conductor cable and gets a reading between the black and white conductors. This indicates:

The cable has correct polarity
A short circuit between the conductors — the cable must be replaced (Correct answer)
Normal leakage resistance in plastic-insulated cable
The cable is properly bonded at both ends

Correct answer: A short circuit between the conductors — the cable must be replaced

Continuity between black and white conductors in a de-energized cable indicates an insulation failure or direct short that requires cable replacement.

Question 58: A multi-wire branch circuit supplying 120/240V loads must have a means to simultaneously disconnect all ungrounded conductors at:

Any accessible location
The distribution panel only
Each outlet served
The point of origin (Correct answer)

Correct answer: The point of origin

NEC 210.4(B) requires multi-wire branch circuits to be provided with a means to simultaneously disconnect all ungrounded conductors at the point of origin.

Question 59: When installing a multiconductor Type NM cable through a series of bored holes in wood studs, what is the minimum distance the edge of the hole must be from the nearest edge of the wood member to avoid the need for a protective steel plate?

3/4 inch
1 inch
1 1/2 inches
1 1/4 inches (Correct answer)

Correct answer: 1 1/4 inches

NEC Section 300.4(A)(1) requires that where cables are installed through bored holes in wood members, the holes shall be bored so that the edge of the hole is not less than 1 1/4 inches from the nearest edge of the wood member. If this distance cannot be maintained, a steel plate or bushing at least 1/16 inch thick must be installed to protect the cable.

Question 60: What is the maximum voltage permitted for branch circuits supplying lampholders of the mogul-base type per NEC 210.6?

150 volts
277 volts
300 volts (Correct answer)
120 volts

Correct answer: 300 volts

NEC 210.6(C) permits up to 300 volts on branch circuits supplying mogul-base lampholders.

Question 61: Per NEC 430.52, the maximum rating of an inverse-time circuit breaker used as motor branch-circuit short-circuit protection for a Design B motor is:

125% of FLC
250% of FLC (Correct answer)
150% of FLC
400% of FLC

Correct answer: 250% of FLC

NEC Table 430.52 allows inverse-time circuit breakers to be sized up to 250% of the motor's full-load current for Design B motors.

Question 62: A contractor is using the optional method under NEC 220.84 to calculate the service load for a new 10-unit apartment building. Which of the following loads must be calculated separately under Article 220, Part III, and added to the result from Table 220.84?

The house loads, such as hallway lighting and a common laundry facility. (Correct answer)
The individual dwelling unit cooking appliance loads.
The general lighting load for each apartment.
The small-appliance circuit loads for each dwelling unit.

Correct answer: The house loads, such as hallway lighting and a common laundry facility.

NEC 220.84 allows for a simplified calculation for the dwelling units themselves by applying a demand factor from Table 220.84 to their combined connected loads. However, any 'house loads' (loads not directly associated with the individual dwelling units) must be calculated separately using the standard method (Part III) and added to the multifamily calculation. Examples include common area lighting, elevators, or central fire alarm systems.

Question 63: What is the maximum penalty per violation that OSHA can impose on an electrical contractor for a willful safety violation as of current federal guidelines?

$161,323 (Correct answer)
$250,000
$16,131
$50,000

Correct answer: $161,323

OSHA's maximum penalty for a willful violation is $161,323 per violation under current adjusted penalty amounts.

Question 64: Which motor protection device responds to both overload current AND phase loss conditions?

Thermal magnetic circuit breaker
Electronic (solid-state) overload relay (Correct answer)
Eutectic-alloy overload relay
Dual-element time-delay fuse

Correct answer: Electronic (solid-state) overload relay

Electronic overload relays monitor all three phases individually and can detect phase loss, imbalance, and overcurrent conditions.

Question 65: A 120V source is connected to a 20-ohm resistor. What is the current flowing through the circuit?

6 A (Correct answer)
0.17 A
2,400 A
100 A

Correct answer: 6 A

Using Ohm's Law: I = V/R = 120/20 = 6 amperes.

Question 66: Per NEC 250.104, what metal piping system within a building must be bonded to the electrical service grounding system?

Interior metal water piping (Correct answer)
Only copper water piping
Only gas piping
All HVAC ductwork regardless of material

Correct answer: Interior metal water piping

NEC 250.104(A) requires interior metal water piping to be bonded to the service equipment enclosure or grounding electrode conductor.

Question 67: A 240V, single-phase service feeds a 10 kW electric range. Using the standard calculation method, what demand load from NEC Table 220.55 applies for one range?

12 kW
10 kW
6 kW
8 kW (Correct answer)

Correct answer: 8 kW

NEC Table 220.55, Column C specifies an 8 kW demand for a single household range rated up to 12 kW.

Question 68: In a commercial building, where must the bonding jumper for a metal raceway containing service-entrance conductors be connected?

At any convenient point along the raceway
Only at the service equipment end
Only at the meter base end
At each end and at every pull point (Correct answer)

Correct answer: At each end and at every pull point

NEC 250.92(B) requires bonding of service raceways at each end and at all intervening points where access is available.

Question 69: What is the minimum size of equipment grounding conductor required for a circuit protected by a 60-ampere overcurrent device using copper conductors?

14 AWG
10 AWG (Correct answer)
12 AWG
8 AWG

Correct answer: 10 AWG

Per NEC Table 250.122, a 60-ampere overcurrent device requires a minimum 10 AWG copper equipment grounding conductor.

Question 70: When calculating dryer load for a multifamily dwelling with 15 dryers, what demand factor applies per NEC Table 220.54?

35%
100%
80%
47% (Correct answer)

Correct answer: 47%

For 15 dryers, NEC Table 220.54 specifies a demand factor of 47%.

Question 71: Which method of accounting recognizes revenue when it is earned and expenses when they are incurred, regardless of when cash is received or paid?

Completed contract method
Percentage of completion method
Accrual basis accounting (Correct answer)
Cash basis accounting

Correct answer: Accrual basis accounting

Accrual accounting records revenue when earned and expenses when incurred, providing a more accurate picture of financial performance over time.

Question 72: What is the minimum clearance required from the top of a service mast to the final point of attachment on a building per NEC 230.24(A)?

12 feet
10 feet (Correct answer)
18 feet
8 feet

Correct answer: 10 feet

NEC 230.24(A) requires service drop conductors to maintain a minimum 10-foot clearance above finished grade at the service entrance.

Question 73: Which NEC article specifically covers the installation requirements for motor circuits and controllers?

Article 430 (Correct answer)
Article 410
Article 440
Article 480

Correct answer: Article 430

NEC Article 430 covers motors, motor circuits, and controllers, including installation, protection, and control requirements.

Question 74: According to OSHA 1910.305, flexible cords must be used only in continuous lengths without splices or taps except when:

Approved splicing connectors or devices are used and the cord is not used in a wet location (Correct answer)
The circuit is protected by a GFCI breaker
The cord is less than 25 feet total length
The splice is covered with electrical tape

Correct answer: Approved splicing connectors or devices are used and the cord is not used in a wet location

OSHA 1910.305 allows splices in flexible cords if they are made with approved connectors or devices and the cord is not routed through walls, ceilings, or floors.

Question 75: Which financial statement shows a company's assets, liabilities, and owner's equity at a specific point in time?

Balance sheet (Correct answer)
Income statement
Cash flow statement
Accounts receivable ledger

Correct answer: Balance sheet

A balance sheet is a snapshot of a company's financial position — assets, liabilities, and equity — at a single date.

Question 76: Three 6-ohm resistors are connected in series. What is the total resistance?

6 ohms
2 ohms
18 ohms (Correct answer)
12 ohms

Correct answer: 18 ohms

Series resistors add directly: R_total = 6 + 6 + 6 = 18 ohms.

Question 77: According to NEC 210.8(A), GFCI protection is required for all 125-volt, 15- and 20-ampere receptacles that serve countertop surfaces in a dwelling unit:

Bedroom
Kitchen (Correct answer)
Living room
Dining room

Correct answer: Kitchen

NEC 210.8(A)(6) specifically requires GFCI protection for receptacles serving countertop surfaces in kitchens of dwelling units due to the proximity of water sources and increased shock risk.

Question 78: What is the minimum grounding electrode conductor size required for a 200-amp copper service per NEC Table 250.66?

6 AWG copper
2 AWG copper
8 AWG copper
4 AWG copper (Correct answer)

Correct answer: 4 AWG copper

NEC Table 250.66 requires a minimum 4 AWG copper grounding electrode conductor for service entrance conductors up to 2/0 AWG.

Question 79: According to NEC Article 310, what is the ampacity of a 12 AWG copper conductor with THHN insulation installed in a conduit with an ambient temperature of 30°C?

15 A
20 A
25 A
30 A (Correct answer)

Correct answer: 30 A

A 12 AWG copper THHN conductor has a base ampacity of 30 A at 75°C column per NEC Table 310.15(B)(16), with no correction needed at 30°C ambient.

Question 80: Under contract law, 'liquidated damages' in a construction contract refer to:

Interest charged on unpaid invoices
Compensation for materials damaged on site
A pre-agreed dollar amount owed for each day the project is delayed beyond completion date (Correct answer)
A penalty for using non-union labor

Correct answer: A pre-agreed dollar amount owed for each day the project is delayed beyond completion date

Liquidated damages are a predetermined sum specified in the contract that the contractor owes the owner for each day the project is not completed by the agreed deadline.

Question 81: What is the primary purpose of dielectric oil in a liquid-filled transformer?

To insulate windings and dissipate heat (Correct answer)
To regulate output voltage
To prevent corrosion on the tank
To lubricate the core laminations

Correct answer: To insulate windings and dissipate heat

Transformer oil serves dual functions: it acts as an electrical insulator between windings and as a cooling medium to transfer heat away from the core and coils.

Question 82: In a commercial load calculation, what demand factor is applied to the first 12.5 kVA of general lighting for an office building?

80%
100% (Correct answer)
125%
50%

Correct answer: 100%

NEC Table 220.42 requires the first 12.5 kVA of general lighting load to be calculated at 100% for commercial occupancies.

Question 83: A 4-inch square by 2-1/8 inch deep metal junction box contains two 12/2 NM cables and one 14/3 NM cable. All conductors are spliced within the box. There are no devices or internal clamps. According to NEC Article 314.16, is this box adequately sized?

No, the box is overfilled by one 14 AWG conductor.
Yes, but only if an extension ring is added.
No, the box is overfilled by one 12 AWG conductor.
Yes, the total calculated volume is less than the box capacity. (Correct answer)

Correct answer: Yes, the total calculated volume is less than the box capacity.

First, determine the box volume from NEC Table 314.16(A): a 4" x 2-1/8" square box has a volume of 30.3 cu. in. Next, calculate the conductor fill using Table 314.16(B). 12/2 NM has two 12 AWG conductors and one ground. So two cables = four 12 AWG and two grounds. 14/3 NM has three 14 AWG conductors and one ground. Total conductors: four 12 AWG, three 14 AWG, and three grounds. Per 314.16(B)(5), all grounds count as one largest ground, so one 12 AWG. Total fill calculation: (4) 12 AWG + (1) 12 AWG (for grounds) + (3) 14 AWG. Volume: (5 x 2.25 cu. in.) + (3 x 2.00 cu. in.) = 11.25 + 6.00 = 17.25 cu. in. Since 17.25 cu. in. is less than the 30.3 cu. in. capacity, the box is adequately sized.

Question 84: A 120/240V single-phase service supplies an electric dryer rated at 5,000 W. What load is used in the standard residential calculation?

5,000 W or 5,000 VA, whichever is larger
4,000 W after demand factor
The nameplate rating or 5,000 VA, whichever is larger (Correct answer)
5,000 W

Correct answer: The nameplate rating or 5,000 VA, whichever is larger

NEC 220.54 states the feeder demand for dryers is the nameplate rating or 5,000 VA, whichever is larger.

Question 85: Per NEC 430.87, if a single motor controller is used for a group of motors, it must have a horsepower rating not less than:

The largest motor HP in the group (Correct answer)
The sum of all motor HP ratings
125% of the largest motor HP
The average HP of all motors

Correct answer: The largest motor HP in the group

NEC 430.87 requires the controller HP rating to be at least equal to the horsepower of the largest motor in the group it controls.

Question 86: Under OSHA 29 CFR 1910.147 (Control of Hazardous Energy), what must each authorized employee do before working on equipment under lockout?

Sign the lockout/tagout log sheet
Verbally notify the supervisor that lockout is in effect
Apply their own personal lock to the energy-isolating device (Correct answer)
Test the equipment with an approved meter

Correct answer: Apply their own personal lock to the energy-isolating device

Each authorized employee must apply their own personal lock to the energy-isolating device so that equipment cannot be re-energized until every worker has removed their lock.

Question 87: A licensed electrical contractor is testing a newly installed service entrance for proper operation. Which test verifies the main bonding jumper is correctly installed?

Measuring resistance between the neutral bus and the grounding electrode conductor
Testing GFCI operation on branch circuits throughout the building
Verifying continuity between the neutral bus and equipment grounding bus in the main panel (Correct answer)
Measuring voltage from line to neutral at the service panel

Correct answer: Verifying continuity between the neutral bus and equipment grounding bus in the main panel

The main bonding jumper connects the neutral bus to the equipment grounding bus in the service equipment; continuity between them confirms it is installed.

Question 88: For a dwelling unit with 240-volt electric range rated at 12 kW, what is the maximum demand load permitted per NEC Table 220.55 Column C?

6 kW
8 kW (Correct answer)
12 kW
9.6 kW

Correct answer: 8 kW

NEC Table 220.55 Column C permits an 8 kW maximum demand for a single household range rated up to 12 kW.

Question 89: A single-phase motor draws 15 amps at 208 volts with a power factor of 0.85. What is the true power consumed?

1,768 watts
2,080 watts
3,120 watts
2,652 watts (Correct answer)

Correct answer: 2,652 watts

True power equals V × I × PF, so 208 × 15 × 0.85 = 2,652 watts.

Question 90: According to OSHA regulations for the construction industry (29 CFR 1926), what is the fundamental principle for protecting workers from electrical hazards like shock and arc flash?

Ensuring all workers wear the minimum level of arc-rated PPE at all times.
Using only insulated tools when working on or near any electrical panel.
Working on circuits and equipment only after they have been de-energized and placed in a lockout/tagout condition. (Correct answer)
Requiring a certified safety monitor to be present for all energized electrical work.

Correct answer: Working on circuits and equipment only after they have been de-energized and placed in a lockout/tagout condition.

OSHA regulations state that live parts should be de-energized before an employee works on or near them unless the employer can demonstrate that de-energizing introduces additional or increased hazards or is infeasible. Lockout/tagout (LOTO) procedures are the primary method for ensuring equipment is safely de-energized before service or maintenance.

Question 91: A licensed electrical contractor operating as a sole proprietor is personally liable for business debts. Which business structure would best protect personal assets?

General partnership
Sole proprietorship
Joint venture
Limited Liability Company (LLC) (Correct answer)

Correct answer: Limited Liability Company (LLC)

An LLC separates personal assets from business liabilities, shielding the owner's personal property from business debts and lawsuits.

Question 92: Under IRS rules, a worker classified as an independent contractor (vs. employee) means the employer is NOT required to:

Withhold federal income taxes and pay payroll taxes on their behalf (Correct answer)
Follow contract terms agreed upon in writing
Pay the worker at all
Provide a safe work environment

Correct answer: Withhold federal income taxes and pay payroll taxes on their behalf

When a worker is a legitimate independent contractor, the hiring company does not withhold income taxes or pay FICA (Social Security and Medicare) payroll taxes on their behalf.

Question 93: A step-down transformer has a primary winding of 800 turns and a secondary winding of 100 turns. If the primary voltage is 480V, what is the secondary voltage?

120V
3840V
240V
60V (Correct answer)

Correct answer: 60V

The relationship between voltage and turns in a transformer is defined by the turns ratio. The formula is (Vp / Vs) = (Np / Ns), where V is voltage, N is the number of turns, 'p' is primary, and 's' is secondary. Rearranging to solve for secondary voltage: Vs = Vp * (Ns / Np). Plugging in the values: Vs = 480V * (100 / 800) = 480V * (1/8) = 60V.

Question 94: What is the maximum rating of an individual branch circuit that can serve a single receptacle outlet per NEC 210.21(B)(1)?

The receptacle may be rated up to 150% of circuit ampacity
The receptacle may be rated at 80% of circuit ampacity
There is no limit if protected by a GFCI
The receptacle rating must equal the branch circuit rating (Correct answer)

Correct answer: The receptacle rating must equal the branch circuit rating

NEC 210.21(B)(1) states a single receptacle on an individual branch circuit must have an ampere rating equal to the branch circuit rating.

Question 95: What is the correct procedure when an electrical contractor identifies unforeseen subsurface conditions that affect the project scope?

Proceed with the work and add the extra costs to the final invoice
Stop all work until the building inspector visits the site
Notify the owner or general contractor in writing and request a change order before proceeding (Correct answer)
Subcontract the additional work to avoid liability

Correct answer: Notify the owner or general contractor in writing and request a change order before proceeding

Unforeseen conditions require prompt written notification to the owner or GC and a formal change order to address scope and cost adjustments before work continues.

Question 96: A conductor has a resistance of 10 ohms at 20°C. If the temperature increases, what happens to its resistance?

Decreases to zero at high temperatures
Remains the same, temperature has no effect
Decreases, because heat reduces electron collision
Increases, because higher temperature increases atomic vibration (Correct answer)

Correct answer: Increases, because higher temperature increases atomic vibration

For most metallic conductors, resistance increases with temperature due to increased atomic vibration impeding electron flow.

Question 97: A 200-amp residential service uses a split-bus panel. How many main disconnect throws are permitted maximum?

2
6 (Correct answer)
4
8

Correct answer: 6

NEC 230.71 permits a maximum of six switches or circuit breakers to serve as the service disconnecting means.

Question 98: The NEC defines a 'qualified person' as someone who:

Has a driver's license
Has skills and knowledge related to electrical equipment and has received safety training (Correct answer)
Has been an electrician for 1 year
Owns their own tools

Correct answer: Has skills and knowledge related to electrical equipment and has received safety training

NEC Article 100 defines qualified person based on skills, knowledge, and safety training.

Question 99: What is the maximum number of disconnecting means permitted for a single service per NEC Section 230.71?

8
4
3
6 (Correct answer)

Correct answer: 6

NEC Section 230.71(A) permits a maximum of six disconnecting means grouped in a single location for each service.

Question 100: What is the power factor in a purely resistive AC circuit?

0
Varies with voltage
1.0 (Correct answer)
0.5

Correct answer: 1.0

In a purely resistive circuit, voltage and current are in phase, so the power factor equals 1.0 (or unity).

Master Electrician / Electrical Contractor License Exam (General)

This exam certifies individuals as Master Electricians or Electrical Contractors, demonstrating comprehensive knowledge of electrical theory, codes, and practical application for safe and compliant electrical installations.

100

Questions

240 min

Time Limit

75%

To Pass

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