NASCLA Accredited Professional Electrical Contractor Exam — Questions and Answers

Question 1: Which safety practice is required when working in a confined space with potential electrical hazards?

Shut off the nearest circuit breaker and proceed
Post a warning sign and work alone to minimize exposure
Obtain a confined space entry permit and test the atmosphere before entry (Correct answer)
Wear rubber-soled boots and enter without a permit if the job is under 30 minutes

Correct answer: Obtain a confined space entry permit and test the atmosphere before entry

Permit-required confined spaces demand an entry permit, atmospheric testing, and an attendant stationed outside before any entry.

Question 2: When estimating transformer installation, which cost factor is often overlooked by inexperienced estimators?

The number of secondary circuits
Rigging, crane, and heavy equipment costs for placement (Correct answer)
The transformer nameplate rating
The primary voltage of the transformer

Correct answer: Rigging, crane, and heavy equipment costs for placement

Large transformers require cranes and rigging equipment for placement, which can be a significant cost that inexperienced estimators miss.

Question 3: When sizing a feeder supplying multiple motors, how is the largest motor's FLA factored into the load calculation per NEC 430.24?

Added at 100% of its FLA
Added at 115% of its FLA
Added at 150% of its FLA
Added at 125% of its FLA (Correct answer)

Correct answer: Added at 125% of its FLA

NEC 430.24 requires that the largest motor's FLA be included at 125% when calculating the total feeder load for a group of motors.

Question 4: Where must bushings be installed when conductors enter a metal enclosure through a knockout?

At every knockout regardless of conductor size (Correct answer)
Only when conductors are larger than 4 AWG
Only when conduit is not used
Only on conductors rated above 600V

Correct answer: At every knockout regardless of conductor size

NEC 300.4(G) requires an insulating fitting or bushing at every point where conductors enter a metal enclosure through a knockout to protect insulation from sharp edges.

Question 5: An electrical contractor is working on a commercial build-out under a lump-sum contract. The owner requests adding 10 additional duplex receptacles that were not in the original plans. What is the first and most appropriate document the contractor should initiate to formally address this change?

A Request for Information (RFI)
A Change Order Proposal (COP) (Correct answer)
An invoice for the additional work
A notice of delay

Correct answer: A Change Order Proposal (COP)

A Change Order Proposal (or Change Order Request) is the standard industry document used to formally propose the scope, cost, and schedule adjustments for additional work requested by the client. An RFI is for clarification, an invoice is for billing after work is approved, and a notice of delay is for schedule impacts, not initiating a scope change.

Question 6: Under NEC Article 504, intrinsically safe systems in hazardous locations use energy-limiting barriers. What must separate intrinsically safe conductors from non-intrinsically safe conductors in the same raceway?

A listed sealing fitting
A grounded metal shield
Physical separation of at least 2 inches within the raceway
They cannot share any raceway regardless of separation (Correct answer)

Correct answer: They cannot share any raceway regardless of separation

NEC 504.30(A) prohibits intrinsically safe conductors from occupying the same raceway, cable tray, or cable as non-intrinsically safe conductors.

Question 7: What OSHA standard requires employers to train workers who face hazards from flames or electric arcs to understand arc flash hazards?

29 CFR 1910.137
29 CFR 1910.335
29 CFR 1910.269 (Correct answer)
29 CFR 1926.416

Correct answer: 29 CFR 1910.269

29 CFR 1910.269 (Electric Power Generation, Transmission, and Distribution) includes arc flash hazard training and PPE requirements.

Question 8: Type AC (armored cable) requires an internal bonding strip. What is its purpose?

To provide a low-impedance fault current path in addition to the armor (Correct answer)
To identify the cable as AC rather than MC
To increase the cable's ampacity
To prevent the armor from cutting conductor insulation

Correct answer: To provide a low-impedance fault current path in addition to the armor

The aluminum bonding strip in Type AC cable works with the steel armor to provide a code-compliant equipment grounding path per NEC 320.108.

Question 9: Which NEC article governs the installation and protection of transformers?

Article 410
Article 480
Article 230
Article 450 (Correct answer)

Correct answer: Article 450

NEC Article 450 covers transformers, including overcurrent protection, installation requirements, and marking.

Question 10: In a separately derived system (e.g., a transformer), where must the system bonding jumper be installed?

At the grounding electrode only
At the source of the separately derived system (Correct answer)
At the main service entrance
At the first overcurrent device 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 11: What does the term 'skin effect' describe in electrical conductors carrying AC current?

Capacitive coupling between adjacent conductors
Insulation breakdown near the surface
Heat dissipation through the conductor jacket
Concentration of current near the conductor surface, increasing effective resistance (Correct answer)

Correct answer: Concentration of current near the conductor surface, increasing effective resistance

Skin effect causes AC current to concentrate near the outer surface of a conductor, reducing effective cross-section and increasing resistance.

Question 12: Under NEC 250.122, what is the minimum size equipment grounding conductor (EGC) for a 60A circuit using copper wire?

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

Correct answer: 10 AWG

NEC Table 250.122 specifies that a 60A overcurrent device requires a minimum 10 AWG copper equipment grounding conductor.

Question 13: What information must an arc flash hazard label on electrical equipment include per NFPA 70E?

Panel schedule reference and feeder conductor size
Manufacturer name, model number, and installation date
Nominal system voltage, arc flash boundary, and required PPE level or incident energy (Correct answer)
Circuit breaker ampere rating and interrupting capacity

Correct answer: Nominal system voltage, arc flash boundary, and required PPE level or incident energy

NFPA 70E Section 130.5(H) requires labels to show voltage, arc flash boundary, and either incident energy or PPE category.

Question 14: What NEC article governs branch circuits?

Article 200
Article 230
Article 220
Article 210 (Correct answer)

Correct answer: Article 210

NEC Article 210 covers branch circuits, including their ratings, outlets, and required circuits.

Question 15: Why is the circuit breaker used in electrical installations?

To regulate the circuit's voltage.
To allow for easy disconnection of appliances.
To disconnect the circuit in case of overload or fault. (Correct answer)
To increase the circuit's current.

Correct answer: To disconnect the circuit in case of overload or fault.

A circuit breaker is a crucial safety device designed to automatically interrupt the flow of electricity when it detects an abnormal condition, such as an overload or a short circuit. This rapid disconnection prevents damage to wiring and appliances, and significantly reduces the risk of electrical fires or shocks. It acts as a protective switch, safeguarding the entire electrical system and its users.

Question 16: Per NEC Article 702, a legally required standby system must restore power to loads within what maximum time after normal supply failure?

60 seconds (Correct answer)
No time requirement; must serve the load
30 seconds
10 seconds

Correct answer: 60 seconds

NEC 702.4 requires legally required standby systems to supply power within 60 seconds of normal supply failure.

Question 17: For signs and outline lighting covered by NEC Article 600, all metal parts of sign enclosures must be grounded. What is the maximum ground conductor resistance permitted?

25 ohms
5 ohms
1 ohm
No resistance limit specified; must meet bonding requirements (Correct answer)

Correct answer: No resistance limit specified; must meet bonding requirements

NEC Article 600 does not specify a maximum resistance value; it requires metal parts to be bonded in accordance with standard grounding and bonding requirements in Article 250.

Question 18: An electrical contractor calculates the total direct and indirect costs for a job to be $120,000. The company wants to achieve a 25% profit margin on the final selling price. What must the total bid price be?

$160,000 (Correct answer)
$150,000
$145,000
$180,000

Correct answer: $160,000

Profit margin is calculated as a percentage of the final selling price, not the cost. The formula is: Bid Price = Total Costs / (1 - Desired Profit Margin). In this case, Bid Price = $120,000 / (1 - 0.25) = $120,000 / 0.75 = $160,000. A common mistake is to apply a 25% markup ($120,000 * 1.25 = $150,000), which results in a lower actual profit margin (20%).

Question 19: A licensed electrical contractor discovers mid-project that the permit they pulled was for a different scope of work than what the owner now requests. What is the correct action?

Notify OSHA and continue working under the original permit
Proceed with the new scope since a permit is already on file
Stop work and obtain an amended or new permit before continuing (Correct answer)
Complete the work and note the change in the final inspection report

Correct answer: Stop work and obtain an amended or new permit before continuing

Work that exceeds or differs from the permitted scope requires an amended permit before proceeding to remain in compliance with adopted building codes.

Question 20: Under OSHA's lockout/tagout standard (29 CFR 1910.147), when must an energy control procedure be documented in writing?

Only for equipment manufactured before 1990
Only when more than 10 workers share the same equipment
When there is more than one energy source or the isolation is not readily apparent (Correct answer)
Whenever the equipment is rated above 480V

Correct answer: When there is more than one energy source or the isolation is not readily apparent

Written procedures are required when equipment has more than one energy source or the lockout steps are not immediately obvious.

Question 21: Per NEC 430.52, a dual-element time-delay fuse used as motor branch circuit short-circuit and ground-fault protection must not exceed what percentage of the motor's full-load current?

150% (Correct answer)
175%
125%
250%

Correct answer: 150%

NEC Table 430.52 allows dual-element time-delay fuses for motor protection up to 175% of the motor's full-load current.

Question 22: Under NEC Article 690 for solar photovoltaic systems, what is the maximum voltage permitted for a PV system installed on or in a one- or two-family dwelling?

300 volts
1000 volts
480 volts
600 volts (Correct answer)

Correct answer: 600 volts

NEC 690.7(A) limits PV system maximum voltage to 600 volts for systems on or in one- and two-family dwellings.

Question 23: In nearly every state, which type of insurance is mandatory for an electrical contracting business that has employees?

General Liability Insurance
Professional Liability (Errors & Omissions) Insurance
Commercial Auto Insurance
Workers' Compensation Insurance (Correct answer)

Correct answer: Workers' Compensation Insurance

State laws almost universally require employers to carry Workers' Compensation insurance. This insurance covers medical expenses and lost wages for employees who are injured on the job, protecting both the employee and the employer from financial hardship and lawsuits related to workplace injuries.

Question 24: A 120V, 60Hz circuit has an inductor with 10Ω inductive reactance. What is the inductance (L) in millihenries?

26.5 mH (Correct answer)
16.7 mH
37.7 mH
1.67 mH

Correct answer: 26.5 mH

XL = 2πfL → L = XL / (2πf) = 10 / (2π × 60) ≈ 26.5 mH.

Question 25: An OSHA compliance officer issues a 'willful' citation. What does this classification mean?

The employer was unaware of the violation
The employer knew of the violation and made no effort to correct it (Correct answer)
The violation caused a recordable injury
A third-party contractor committed the violation

Correct answer: The employer knew of the violation and made no effort to correct it

A willful citation means the employer had knowledge of the hazardous condition and intentionally chose not to correct it.

Question 26: Which of the following is NOT permitted to be used as a grounding electrode per NEC 250.52?

Ground ring
Underground gas piping system (Correct answer)
Concrete-encased rebar
Metal underground water pipe

Correct answer: Underground gas piping system

NEC 250.52(B) explicitly prohibits underground gas piping systems from being used as a grounding electrode.

Question 27: Per NEC Table 220.42, what demand factor applies to the first 3,000 VA of residential lighting load?

125%
100% (Correct answer)
75%
50%

Correct answer: 100%

NEC Table 220.42 specifies a 100% demand factor for the first 3,000 VA of residential lighting load; demand factors drop for additional load.

Question 28: A squirrel cage induction motor is classified as what type of motor?

DC series motor
Universal motor
AC induction motor (Correct answer)
Synchronous motor

Correct answer: AC induction motor

A squirrel cage induction motor is the most common AC induction motor, named for its rotor conductor arrangement that resembles a squirrel cage.

Question 29: In a commercial building, a metal underground water pipe is used as the primary grounding electrode. Which of the following statements is correct regarding this installation?

The water pipe must be in direct contact with the earth for at least 8 feet.
The metal water pipe is sufficient and no other electrodes are needed.
The grounding electrode conductor must be bonded to the pipe within 10 feet of where it enters the building.
A supplemental grounding electrode is required. (Correct answer)

Correct answer: A supplemental grounding electrode is required.

According to NEC 250.53(D)(2), a metal underground water pipe electrode must be supplemented by an additional electrode. This is because the metal water pipe is subject to damage or replacement (e.g., with plastic pipe), which would result in the loss of the grounding electrode for the system.

Question 30: In a patient care space of a health care facility, branch circuits must be installed using a method that provides an effective ground-fault current path. Which of the following meets this requirement per NEC Article 517?

Type NM cable with an equipment grounding conductor.
Direct-burial cable run concealed in the wall.
A metal raceway or a cable with a metallic armor or sheath. (Correct answer)
PVC conduit with an insulated copper equipment grounding conductor.

Correct answer: A metal raceway or a cable with a metallic armor or sheath.

NEC 517.13(A) requires that branch circuits serving patient care spaces be installed in a metal raceway or be a cable assembly with a metallic armor or sheath, such as Type MC or AC cable. This is to ensure a redundant and reliable equipment grounding path to minimize electrical hazards to patients.

Question 31: What does 'total cost method' refer to in construction claims, and why do courts disfavor it?

Billing all overhead costs as a lump sum; disfavored because it lacks itemization
Calculating damages as the difference between total costs incurred and the contract amount; disfavored because it assumes all cost overruns are the owner's fault (Correct answer)
Pricing change orders based on installed material costs only; disfavored because it ignores labor
Recovering attorney fees as part of a claim; disfavored as it expands litigation

Correct answer: Calculating damages as the difference between total costs incurred and the contract amount; disfavored because it assumes all cost overruns are the owner's fault

The total cost method assumes the contractor bid correctly and all cost overruns are owner-caused, which courts distrust because contractors may have underbid or caused some overruns themselves.

Question 32: Which NEC table provides demand factors for household electric ranges and counter-mounted cooking units?

Table 220.54
Table 220.57
Table 220.55 (Correct answer)
Table 220.56

Correct answer: Table 220.55

NEC Table 220.55 provides demand factors and column notes for calculating feeder loads for household electric ranges, wall ovens, and counter-mounted cooking units.

Question 33: Per OSHA 29 CFR 1926.403(b)(2), electrical equipment in a wet or damp location must be:

Inspected daily by a competent person
Protected by a double-pole breaker only
Rated for wet locations or enclosed in a weatherproof enclosure (Correct answer)
Disconnected and locked out when not in active use

Correct answer: Rated for wet locations or enclosed in a weatherproof enclosure

Equipment in wet or damp locations must be listed and identified for use in such locations or enclosed in a weatherproof enclosure.

Question 34: OSHA's Hazard Communication Standard (29 CFR 1910.1200) requires Safety Data Sheets (SDS) to follow which format?

8-section EPA format
16-section GHS format (Correct answer)
12-section ANSI format
NFPA 704 diamond sections

Correct answer: 16-section GHS format

OSHA aligned its HazCom standard with the Globally Harmonized System (GHS), requiring a standardized 16-section SDS.

Question 35: If a 120V outlet supplies a 1,440W load, what is the current draw?

12 A (Correct answer)
16 A
120 A
8 A

Correct answer: 12 A

I = P / V = 1,440 / 120 = 12 A.

Question 36: In a health care facility critical branch, NEC 517.33 requires that the critical branch be transferred to alternate power within what maximum time after normal power failure?

30 seconds
10 seconds (Correct answer)
20 seconds
60 seconds

Correct answer: 10 seconds

NEC 517.33 requires the critical branch of a healthcare facility to be automatically transferred to alternate power within 10 seconds of normal power loss.

Question 37: Under NEC Article 517, a 'patient care vicinity' in a healthcare facility extends how far from a patient bed?

3 feet horizontally and 5 feet above the floor
6 feet horizontally and 7.5 feet above the floor (Correct answer)
4 feet horizontally and 6 feet above the floor
5 feet horizontally and 8 feet above the floor

Correct answer: 6 feet horizontally and 7.5 feet above the floor

NEC 517.2 defines the patient care vicinity as the space within 6 feet horizontally and 7.5 feet above the floor from the patient bed.

Question 38: In an agricultural building covered by NEC Article 547, which wiring method is NOT permitted due to moisture and corrosive atmosphere concerns?

Liquidtight flexible nonmetallic conduit
Type NM cable (Correct answer)
Type UF cable
Rigid nonmetallic conduit (RNC)

Correct answer: Type NM cable

NEC 547.5 prohibits Type NM cable in agricultural buildings because the moisture and corrosive atmosphere degrade its jacket and conductors.

Question 39: Which wiring method is specifically listed by the NEC as suitable for direct burial without conduit protection?

USE-2 cable (Correct answer)
AC cable
THHN conductors
NM-B cable

Correct answer: USE-2 cable

USE-2 (Underground Service Entrance) cable is rated and listed for direct burial applications without requiring conduit.

Question 40: Which of the following best describes reactive power (VAR)?

Power stored and returned by inductive or capacitive elements (Correct answer)
Power dissipated as heat in resistors
Total power delivered by the source
Power consumed by the load's mechanical output

Correct answer: Power stored and returned by inductive or capacitive elements

Reactive power represents energy oscillating between the source and reactive elements (inductors/capacitors) without being consumed.

Question 41: What is the purpose of grounding in electrical systems?

To provide a safe path for fault currents. (Correct answer)
To increase current flow.
To prevent overloading the circuit.
To store electrical energy.

Correct answer: To provide a safe path for fault currents.

Grounding in electrical systems provides a safe path for fault currents to dissipate into the earth, rather than flowing through a person or damaging equipment. This protective measure ensures that in the event of an electrical fault, excess current is safely diverted. It is a fundamental safety feature designed to prevent electric shock and reduce fire hazards.

Question 42: In a theater or similar occupancy covered by NEC Article 520, portable stage switchboards must be protected by overcurrent devices not exceeding what percentage of the switchboard's ampere rating?

100%
125% (Correct answer)
150%
200%

Correct answer: 125%

NEC 520.25 requires overcurrent protection for portable stage switchboards not exceeding 125% of the switchboard ampere rating.

Question 43: Which statement correctly describes Lenz's Law?

Current through an inductor cannot change instantaneously
An induced current opposes the change in magnetic flux that caused it (Correct answer)
Induced EMF is proportional to resistance
A magnetic field exerts force on a current-carrying conductor

Correct answer: An induced current opposes the change in magnetic flux that caused it

Lenz's Law states the induced EMF always drives a current that opposes the change in flux (conservation of energy).

Question 44: What is the primary difference between a switchboard and a metal-clad switchgear assembly?

Switchboards have a higher interrupting capacity than switchgear
Metal-clad switchgear is fully enclosed with drawout components providing greater protection than open-construction switchboards (Correct answer)
Switchboards are for outdoor use only; switchgear is for indoor use only
There is no practical electrical difference between the two assemblies

Correct answer: Metal-clad switchgear is fully enclosed with drawout components providing greater protection than open-construction switchboards

Metal-clad switchgear uses enclosed drawout circuit breakers with interlocks and bus barriers, providing higher protection levels than switchboards which are typically accessible from the front only.

Question 45: In a project schedule created using the Critical Path Method (CPM), which of the following best describes the activities that make up the 'critical path'?

All tasks that are performed by the electrical contractor.
The sequence of tasks that have zero 'float' or 'slack' time. (Correct answer)
The first set of activities to be completed, such as site mobilization.
The tasks with the highest material costs.

Correct answer: The sequence of tasks that have zero 'float' or 'slack' time.

The Critical Path is the longest sequence of dependent tasks through the project schedule. Activities on this path have no slack or 'float,' meaning any delay in their execution will directly delay the overall project completion date.

Question 46: When installing conductors in parallel, which of the following is a requirement according to NEC 310.10(G)?

The conductors must be the same length, material, and size, and terminated in the same manner. (Correct answer)
The conductors must be of different sizes to accommodate voltage drop.
The conductors can be made of different materials, such as copper and aluminum.
The conductors are only required to be the same length and material.

Correct answer: The conductors must be the same length, material, and size, and terminated in the same manner.

NEC 310.10(G) requires that when conductors are run in parallel, they must be the same length, made of the same conductor material, have the same circular mil area (size), have the same insulation type, and be terminated in the same manner. This ensures that the current divides evenly between the conductors.

Question 47: A state adopts the 2023 NEC but a municipality within the state amends it to prohibit aluminum wiring in residential work. Which standard applies to residential projects in that municipality?

The state NEC adoption always overrides local amendments
The 2023 NEC applies because federal law supersedes local ordinances
The contractor may choose whichever standard is less restrictive
The local amendment applies because local AHJs may amend adopted codes (Correct answer)

Correct answer: The local amendment applies because local AHJs may amend adopted codes

Local authorities having jurisdiction may amend adopted model codes to be more restrictive, and those local amendments govern within their jurisdiction.

Question 48: An electrical contractor is installing light switches in a newly constructed public restroom. To comply with the Americans with Disabilities Act (ADA) standards for accessibility, where must the switches be located?

Within a reach range of 15 inches minimum and 48 inches maximum from the finished floor. (Correct answer)
Exactly 36 inches from the finished floor to align with the door handle.
No higher than 60 inches from the finished floor, centered on the latch side of the door.
At a standard height of 52 inches from the finished floor for all public spaces.

Correct answer: Within a reach range of 15 inches minimum and 48 inches maximum from the finished floor.

The Americans with Disabilities Act (ADA) Accessibility Guidelines (ADAAG) require controls, including light switches, to be placed within an accessible reach range. For an unobstructed side or forward reach, the operable part of the control must be located between 15 inches and 48 inches above the finished floor.

Question 49: What is 'locked rotor current' (LRC) in a motor circuit?

The reduced current drawn at no-load speed
The current drawn after the motor reaches synchronous speed
The high inrush current drawn when voltage is applied and the rotor has not yet begun turning (Correct answer)
The steady-state running current at full load

Correct answer: The high inrush current drawn when voltage is applied and the rotor has not yet begun turning

Locked rotor current is the maximum inrush current drawn from the supply when rated voltage is applied to a motor whose rotor is stationary.

Question 50: What does a motor's service factor (SF) of 1.15 indicate?

The motor efficiency is 115% of standard
The motor insulation is Class F rated
The motor starting torque is 15% above average
The motor can operate continuously at 115% of its rated load (Correct answer)

Correct answer: The motor can operate continuously at 115% of its rated load

A service factor of 1.15 means the motor can operate continuously at 115% of its rated nameplate horsepower without harm under standard conditions.

Question 51: When bonding metal water piping in a building, the bonding jumper must be connected to the piping at a point within how many feet of where the water service enters the building?

25 feet
10 feet
2 feet
5 feet (Correct answer)

Correct answer: 5 feet

NEC 250.68(C)(1) requires the bonding connection to interior metal water piping within 5 feet of where the pipe enters the building.

Question 52: Which bonding method is acceptable for rigid metal conduit (RMC) at a service entrance where the conduit is used as the raceway for service-entrance conductors?

No bonding is required for RMC at service entrances
Grounding bushings with bonding jumper
Listed fittings designed for bonding, grounding bushings, or bonding locknuts (Correct answer)
Standard locknuts only (two locknuts)

Correct answer: Listed fittings designed for bonding, grounding bushings, or bonding locknuts

NEC 250.92(B) permits listed fittings, grounding/bonding bushings, or bonding locknuts for bonding service raceways.

Question 53: In a unit price contract, the contractor is paid based on:

A fixed total regardless of quantities
Cost plus a fixed percentage fee
The original estimate quantities only
Actual field-measured quantities times the agreed unit price (Correct answer)

Correct answer: Actual field-measured quantities times the agreed unit price

Under a unit price contract, final payment is calculated by multiplying actual field-measured quantities by the agreed unit prices for each bid item.

Question 54: What is the primary function of the Main Bonding Jumper (MBJ) in a service panel?

To bond the service neutral conductor and the equipment grounding conductor(s) to the service disconnect enclosure. (Correct answer)
To connect the grounding electrode conductor to the panel enclosure.
To connect the equipment grounding conductors to the neutral bar.
To provide a terminal for connecting bonding jumpers from other systems like telephone and CATV.

Correct answer: To bond the service neutral conductor and the equipment grounding conductor(s) to the service disconnect enclosure.

The Main Bonding Jumper (MBJ), as defined in NEC Article 100 and required by 250.24(C) and 250.28, provides the critical connection between the grounded conductor (service neutral), the equipment grounding conductors, and the service disconnect enclosure. This connection creates the effective ground-fault current path back to the source.

Question 55: An electrical contractor's crew discovers a trench that has been open for two days and is 6 feet deep in sandy soil. Per OSHA, what must be done before workers enter?

Post a warning sign at the trench edge
Test the soil with a penetrometer only
Assign a designated spotter at the surface
Shore, slope, or shield the trench walls (Correct answer)

Correct answer: Shore, slope, or shield the trench walls

OSHA 29 CFR 1926.652 requires trenches 5 feet or deeper to be protected by sloping, shoring, or shielding before entry.

Question 56: Which agency oversees and enforces electrical code compliance in the U.S.?

The Occupational Safety and Health Administration (OSHA). (Correct answer)
The U.S. Department of Energy.
The National Fire Protection Association (NFPA).
The Federal Electrical Commission.

Correct answer: The Occupational Safety and Health Administration (OSHA).

In the U.S., the Occupational Safety and Health Administration (OSHA) is the primary agency responsible for overseeing and enforcing electrical code compliance, particularly in workplaces. While the National Fire Protection Association (NFPA) develops the National Electrical Code (NEC), OSHA ensures that employers adhere to these standards to provide a safe working environment and prevent electrical hazards.

Question 57: When working on a construction site with temporary power, GFCI protection or an assured equipment grounding conductor program (AEGCP) is required by which regulation?

NEC Article 210.8
NFPA 70E Article 130
OSHA 29 CFR 1926.404(b)(1) (Correct answer)
OSHA 29 CFR 1910.303

Correct answer: OSHA 29 CFR 1926.404(b)(1)

OSHA 29 CFR 1926.404(b)(1) mandates either GFCI protection or an AEGCP for all 120V single-phase 15A and 20A receptacle outlets on construction sites.

Question 58: Slip in an induction motor is defined as the difference between:

Full-load current and no-load current
Synchronous speed and rotor speed (Correct answer)
Line frequency and motor frequency
Applied voltage and induced voltage

Correct answer: Synchronous speed and rotor speed

Slip = (Ns - Nr) / Ns × 100%, representing the rotor's lag behind the rotating magnetic field.

Question 59: Under OSHA 29 CFR 1926.501, when is fall protection required for workers on walking/working surfaces at construction sites?

At heights of 8 feet or more
At heights of 6 feet or more (Correct answer)
At heights of 4 feet or more
At heights of 10 feet or more

Correct answer: At heights of 6 feet or more

OSHA's construction fall protection standard requires fall protection for workers at elevations of 6 feet or more above a lower level.

Question 60: A risk assessment matrix in electrical safety management is used to:

Establish the minimum PPE category for a given voltage level
Calculate the incident energy of an arc flash event
Determine the number of LOTO devices required for a task
Prioritize hazards by combining their likelihood of occurrence with the severity of potential injury (Correct answer)

Correct answer: Prioritize hazards by combining their likelihood of occurrence with the severity of potential injury

A risk matrix plots probability against consequence to rank hazards so resources are directed toward the highest-priority risks first.

Question 61: Kirchhoff's Voltage Law (KVL) states that the algebraic sum of all voltages around any closed loop is:

Infinite
Zero (Correct answer)
Equal to the largest resistor drop
Equal to the source voltage

Correct answer: Zero

KVL states that the sum of all voltage rises and drops around any closed loop must equal zero.

Question 62: Per NEC 310.15, what adjustment factor must be applied when more than three current-carrying conductors are bundled together in a raceway?

Conductors must be upsized by one AWG size automatically
No adjustment is needed
A derating factor from NEC Table 310.15(C)(1) must be applied (Correct answer)
The circuit must be limited to 15 amperes maximum

Correct answer: A derating factor from NEC Table 310.15(C)(1) must be applied

NEC 310.15(C)(1) requires applying adjustment factors from Table 310.15(C)(1) when more than three current-carrying conductors are in a raceway or cable.

Question 63: Which NEC article covers grounding and bonding?

Article 230
Article 260
Article 240
Article 250 (Correct answer)

Correct answer: Article 250

NEC Article 250 covers all requirements for grounding and bonding of electrical systems.

Question 64: Under NEC Article 626, electrolytic cells used in industrial processes must have their DC power supply disconnecting means able to de-energize the cell circuits within what maximum time?

Instantaneous (Correct answer)
10 seconds
30 seconds
5 seconds

Correct answer: Instantaneous

NEC 626.12 requires that the disconnecting means for electrolytic cell lines be capable of de-energizing them quickly enough to protect personnel, which means it must operate instantaneously.

Question 65: What does the term 'addendum' refer to during the bidding process?

A change order after contract award
A written modification issued to all bidders before bid opening (Correct answer)
A contractor's request for information
A supplemental insurance certificate

Correct answer: A written modification issued to all bidders before bid opening

An addendum is a written modification to the bidding documents issued by the owner or architect to all bidders before the bid deadline.

Question 66: What NEC section governs the bonding of metal gas piping systems in a building?

NEC 250.28
NEC 250.64
NEC 250.104(B) (Correct answer)
NEC 250.52

Correct answer: NEC 250.104(B)

NEC 250.104(B) requires metal gas piping to be bonded to the electrical service equipment, the grounded conductor, or the grounding electrode conductor.

Question 67: What is the unit of measurement for electrical resistance?

Ohms. (Correct answer)
Watts.
Volts.
Amps.

Correct answer: Ohms.

Ohms (Ω) are the standard unit of measurement for electrical resistance, which quantifies how much a material opposes the flow of electric current. Resistance is a key component in Ohm's Law (V=IR) and influences the amount of current that will flow through a circuit at a given voltage. Understanding resistance is vital for designing efficient and safe electrical systems.

Question 68: Per NEC Table 310.15(C)(1), what ampacity correction factor applies when 4 to 6 current-carrying conductors are bundled in the same conduit?

85% derating
90% derating
80% derating (Correct answer)
70% derating

Correct answer: 80% derating

NEC Table 310.15(C)(1) requires an 80% derating factor when 4 to 6 current-carrying conductors are installed in the same raceway or cable.

Question 69: The synchronous speed of a 4-pole induction motor operating on a 60Hz system is:

1,200 RPM
3,600 RPM
1,800 RPM (Correct answer)
900 RPM

Correct answer: 1,800 RPM

Ns = (120 × f) / P = (120 × 60) / 4 = 1,800 RPM.

Question 70: When installing a grounding electrode conductor in a metal raceway, what additional requirement applies?

The raceway must be bonded to the grounding electrode conductor at both ends (Correct answer)
The raceway must contain only the grounding conductor, no other wiring
The raceway must be at least 1-inch trade size
The raceway must be PVC-coated to prevent corrosion

Correct answer: The raceway must be bonded to the grounding electrode conductor at both ends

NEC 250.64(E) requires that when a GEC is installed in metal raceway, the raceway must be bonded to the GEC at both ends to prevent inductive choke.

Question 71: Per NEC 547.9, the disconnecting means for agricultural buildings must be located outside the building or inside near the point of entry. What is the maximum number of disconnects permitted as the service disconnecting means?

No limit specified
2
6 (Correct answer)
4

Correct answer: 6

NEC 230.71 permits a maximum of six disconnects as the service disconnecting means, which also applies to agricultural buildings under Article 547.

Question 72: Which term describes the practice of a general contractor using a subcontractor's bid to win a project, then negotiating a lower price after award?

Value engineering
Price leveling
Bid shopping (Correct answer)
Scope clarification

Correct answer: Bid shopping

Bid shopping is the unethical practice of using a subcontractor's bid price to solicit lower prices from competitors after the prime contract is awarded.

Question 73: An electrical contractor is terminated for convenience by a private owner. Which costs is the contractor typically entitled to recover?

Only direct costs for work already performed
The full contract price as if all work had been completed
Costs for work performed, costs of demobilization, and a reasonable profit on work completed but not anticipated profit on the uncompleted work (Correct answer)
Only the cost of materials already purchased and installed

Correct answer: Costs for work performed, costs of demobilization, and a reasonable profit on work completed but not anticipated profit on the uncompleted work

Termination for convenience entitles the contractor to costs incurred plus reasonable profit on work done, but generally not lost profits on the unperformed portion of the contract.

Question 74: A capacitor-start motor uses a run capacitor to improve efficiency. What does the run capacitor primarily improve?

Power factor and running efficiency (Correct answer)
Starting torque only
Locked-rotor current
Insulation resistance

Correct answer: Power factor and running efficiency

A run capacitor remains in the circuit during normal operation to correct power factor and improve running efficiency.

Question 75: When a bid is submitted on a 'lump sum' basis, the contractor is agreeing to:

Share any cost savings with the owner equally
Complete the defined scope for one fixed total price (Correct answer)
Bill the owner based on actual hours worked
Provide monthly cost reports for owner approval

Correct answer: Complete the defined scope for one fixed total price

A lump sum contract requires the contractor to complete all defined scope for one agreed total price, bearing the risk of cost overruns.

Question 76: Per NEC 450.21(A), a dry-type transformer rated 112.5 kVA or less may be installed indoors without a transformer vault if it is:

Installed only on the lowest floor of the building
Only installed in a locked electrical room
Placed in a listed enclosure only
Separated from combustible material by at least 12 inches or by a fire-resistant heat-insulating barrier (Correct answer)

Correct answer: Separated from combustible material by at least 12 inches or by a fire-resistant heat-insulating barrier

NEC 450.21(A) permits dry-type transformers 112.5 kVA or less to be installed indoors if separated from combustible materials by at least 300 mm (12 in.) or by a fire-resistant, heat-insulating barrier.

Question 77: What is a circuit breaker used for in electrical systems?

To interrupt the electrical flow in case of overloads. (Correct answer)
To regulate the current.
To increase the electrical flow.
To store excess electricity.

Correct answer: To interrupt the electrical flow in case of overloads.

A circuit breaker is a crucial safety device in electrical systems, designed to automatically interrupt the electrical flow in case of overloads or short circuits. When an excessive current is detected, the breaker 'trips,' cutting power to prevent damage to wiring and appliances. This protects against overheating and potential electrical fires, enhancing overall system safety.

Question 78: What is the phase angle of a circuit with 30Ω resistance and 40Ω total reactance (net inductive)?

36.87°
53.13° (Correct answer)
45°
90°

Correct answer: 53.13°

θ = arctan(X/R) = arctan(40/30) = arctan(1.333) ≈ 53.13°.

Question 79: Per NEC 450.9, indoor transformer ventilation must be adequate to:

Limit the temperature rise of the transformer to its nameplate rating under full-load conditions (Correct answer)
Keep transformer surface temperature below 40°C at all times
Provide a minimum of 6 air changes per hour in the transformer room
Limit ambient temperature to no more than 25°C

Correct answer: Limit the temperature rise of the transformer to its nameplate rating under full-load conditions

NEC 450.9 requires that ventilation be provided so that transformer temperature does not exceed its nameplate temperature rise under full-load operation.

Question 80: Which of the following actions by an electrical contractor is most likely to result in disciplinary action by the state licensing board?

Providing a written estimate before beginning work
Completing a project ahead of schedule
Subcontracting specialty work to another licensed contractor
Allowing an unlicensed individual to pull permits under the contractor's license (Correct answer)

Correct answer: Allowing an unlicensed individual to pull permits under the contractor's license

Allowing an unlicensed person to use a licensed contractor's name or license number to pull permits—known as license lending—is a serious violation that can result in suspension or revocation.

Question 81: Three resistors of 6Ω, 12Ω, and 4Ω are connected in parallel. What is the total equivalent resistance?

2Ω (Correct answer)
0.5Ω
7.3Ω
22Ω

Correct answer: 2Ω

1/Rt = 1/6 + 1/12 + 1/4 = 2/12 + 1/12 + 3/12 = 6/12; Rt = 2Ω.

Question 82: What is the function of a 'no damage for delay' clause in a construction contract?

It eliminates liquidated damages if the contractor finishes late
It prevents the contractor from recovering monetary compensation for delays caused by the owner (Correct answer)
It establishes that delay damages are limited to direct costs only
It waives the owner's right to claim delay damages against the contractor

Correct answer: It prevents the contractor from recovering monetary compensation for delays caused by the owner

A no damage for delay clause limits the contractor's remedy for owner-caused delays to time extensions only, barring monetary compensation for delay costs.

Question 83: What does 'prevailing wage' mean in the context of electrical bidding on public projects?

The average wage paid in the private sector
The highest wage paid to any electrician in the region
The union wage agreed to in a collective bargaining agreement
A government-mandated minimum wage rate for specific trades on public work (Correct answer)

Correct answer: A government-mandated minimum wage rate for specific trades on public work

Prevailing wage laws (such as the Davis-Bacon Act) require contractors on public projects to pay workers at least the locally determined wage rate for their classification.

Question 84: NEC Article 700 covers emergency systems. These systems must be tested under load within how many hours after installation and at least every how often thereafter?

12 hours after installation; every 6 months
24 hours after installation; every 6 months (Correct answer)
72 hours after installation; annually
30 days after installation; every 12 months

Correct answer: 24 hours after installation; every 6 months

NEC 700.3(B) requires emergency systems to be tested within 24 hours of installation and at intervals not exceeding 6 months.

Question 85: What is the significance of grounding in electrical safety?

It helps in the regulation of electrical circuits.
It reduces the overall cost of the installation.
It increases the power supply to the circuit.
It prevents electric shocks and fires by directing excess electricity to the earth. (Correct answer)

Correct answer: It prevents electric shocks and fires by directing excess electricity to the earth.

Grounding is a critical safety feature in electrical systems that provides a low-resistance path for electricity to flow directly into the earth in the event of a fault. This protective measure ensures that if a live wire accidentally touches a metal casing or component, the fault current is safely diverted away from people and equipment. By doing so, grounding prevents dangerous voltage buildup, significantly reducing the risk of electric shocks and electrical fires.

Question 86: In a hazardous location classified as Class I, Division 1, what is the primary concern that dictates the wiring methods and equipment used?

The presence of easily ignitable fibers or flyings.
The presence of flammable gases or vapors is expected under normal operating conditions. (Correct answer)
The presence of combustible dust during normal operation.
The presence of flammable gases or vapors under abnormal conditions.

Correct answer: The presence of flammable gases or vapors is expected under normal operating conditions.

NEC Article 500 defines a Class I, Division 1 location as an area where ignitible concentrations of flammable gases or vapors can exist under normal operating conditions. This high probability of a hazardous atmosphere necessitates the most stringent wiring and equipment protection methods to prevent ignition.

Question 87: Per NEC 334.15, Type NM cable must be protected from physical damage where it is exposed and runs within how many feet of the floor in an accessible area?

6 feet
8 feet
4.5 feet (Correct answer)
7 feet

Correct answer: 4.5 feet

NEC 334.15(B) requires NM cable to be protected by conduit or other means where it runs within 4.5 feet (1.4 m) of the floor in accessible areas.

Question 88: Structural steel of a building may be used as a grounding electrode if it is connected to at least how many ground rods, concrete-encased electrodes, or ground rings?

One
Three
Four
Two (Correct answer)

Correct answer: Two

NEC 250.52(A)(2) permits building steel as a grounding electrode when it is connected to at least two ground rods, concrete-encased electrodes, or ground rings.

Question 89: What is the maximum allowable distance between receptacles in a marina or boatyard pedestal installation per NEC Article 553?

The receptacle must be within 15 feet of each slip
Each slip must have its own dedicated receptacle within 50 feet
No specific distance limit is specified in NEC 553
The receptacle must be within 30 feet of the boat connection point (Correct answer)

Correct answer: The receptacle must be within 30 feet of the boat connection point

NEC 553.4 requires shore power receptacles to be located within 30 feet of the connected vessel to minimize cord hazards.

Question 90: A job hazard analysis (JHA) is best described as:

An OSHA inspection checklist
A formal study that identifies hazards associated with specific job tasks before work begins (Correct answer)
A permit required before entering a confined space
A post-accident investigation report

Correct answer: A formal study that identifies hazards associated with specific job tasks before work begins

A JHA proactively identifies hazards associated with each step of a task so controls can be implemented beforehand.

Question 91: Which wiring method is specifically listed for use in ducts, plenums, or other air-handling spaces without restriction?

EMT with THHN conductors (Correct answer)
Type MC cable
Electrical nonmetallic tubing (ENT)
Type AC cable

Correct answer: EMT with THHN conductors

EMT with THHN conductors is permitted in environmental air spaces; Type MC, AC, and ENT have restrictions under NEC 300.22.

Question 92: Which OSHA standard specifically governs electrical safety requirements for construction sites?

29 CFR 1926.100
29 CFR 1910.303
29 CFR 1926.400 (Correct answer)
29 CFR 1910.147

Correct answer: 29 CFR 1926.400

29 CFR 1926.400 (Subpart K) is OSHA's primary electrical safety standard for construction.

Question 93: What is the minimum horsepower rating required for a motor disconnecting means per NEC 430.110?

125% of the motor's HP rating
150% of the motor's HP rating
Equal to the motor's HP rating (Correct answer)
115% of the motor's HP rating

Correct answer: Equal to the motor's HP rating

NEC 430.110(A) requires the motor disconnect to have an HP rating at least equal to the motor's HP rating at the applied voltage.

Question 94: Which type of construction contract generally carries the highest level of financial risk for the project owner and the lowest for the contractor?

Lump Sum (Fixed Price)
Cost-Plus (Cost Reimbursement) (Correct answer)
Unit Price
Guaranteed Maximum Price (GMP)

Correct answer: Cost-Plus (Cost Reimbursement)

In a Cost-Plus contract, the owner agrees to pay for all actual project costs (labor, materials, subcontracts) plus an agreed-upon fee for the contractor's overhead and profit. This structure shifts the risk of cost overruns from the contractor to the owner.

Question 95: OSHA defines an 'authorized employee' under the lockout/tagout standard as someone who:

Locks out or tags out machines to perform servicing or maintenance (Correct answer)
Works in the same area as the equipment being serviced
Has been employed for more than 90 days
Has been trained to recognize hazardous energy sources

Correct answer: Locks out or tags out machines to perform servicing or maintenance

An authorized employee is the worker who actually applies the lockout/tagout device to control hazardous energy.

Question 96: An electrical contractor is working under a design-build contract. Which responsibility is unique to design-build compared to design-bid-build?

Submitting shop drawings for approval
Providing a performance bond
Assuming liability for both design errors and construction defects (Correct answer)
Providing a certificate of insurance

Correct answer: Assuming liability for both design errors and construction defects

In design-build, the contractor assumes responsibility for both design and construction, eliminating the owner's ability to blame the designer separately from the builder.

Question 97: A balanced three-phase load has a true power of 25 kW and a power factor of 0.85. What is the apparent power of the load?

32.75 kVA
25.00 kVA
21.25 kVA
29.41 kVA (Correct answer)

Correct answer: 29.41 kVA

The relationship between true power (P), apparent power (S), and power factor (PF) is given by the formula: PF = P / S. To find the apparent power, rearrange the formula to S = P / PF. S = 25 kW / 0.85 = 29.41 kVA.

Question 98: What is the primary function of a construction manager acting in an 'agency' role (CM-Agent) as opposed to a 'construction manager at-risk' (CMAR)?

The CM-Agent is responsible for design errors as the designer of record
The CM-Agent acts as the owner's representative and advisor without holding trade contracts or bearing construction cost risk (Correct answer)
The CM-Agent holds all subcontracts and bears the construction risk
The CM-Agent provides the performance bond for the project

Correct answer: The CM-Agent acts as the owner's representative and advisor without holding trade contracts or bearing construction cost risk

A CM-Agent advises the owner and manages the project on their behalf but the owner holds contracts directly with trade contractors and retains the construction cost risk.

Question 99: What is the primary purpose of a motor overload relay?

To protect against voltage surges from the utility
To protect against short circuits in the branch circuit
To provide ground fault protection for personnel
To protect motor windings from damage due to overheating (Correct answer)

Correct answer: To protect motor windings from damage due to overheating

Motor overload relays monitor current over time and trip to prevent motor windings from overheating under sustained overload conditions.

Question 100: What does a fuse do in an electrical circuit?

It protects the circuit by breaking the connection when the current is too high. (Correct answer)
It provides power to the circuit.
It controls the voltage.
It increases the current.

Correct answer: It protects the circuit by breaking the connection when the current is too high.

A fuse is a critical safety device in an electrical circuit designed to protect against overcurrent. It contains a thin wire that melts and breaks the circuit connection if the current exceeds a safe level. This interruption prevents damage to electrical components and wiring, significantly reducing the risk of overheating and electrical fires.

NASCLA Accredited Professional Electrical Contractor Exam

The NASCLA Accredited Professional Electrical Contractor (Master/Unlimited) exam tests knowledge of the National Electrical Code (NEC), electrical theory, wiring methods, equipment, safety standards, and project management required for electrical contractor licensure. It is an open-book examination accepted by multiple state licensing boards.

100

Questions

270 min

Time Limit

75%

To Pass

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