ICC E2 Commercial Electrical Inspector — Questions and Answers

Question 1: A technician needs to work on a 480V panelboard where one side has an exposed energized bus and the opposite side has a concrete block (grounded) wall. Which working space Condition applies?

Condition 4
Condition 3
Condition 1
Condition 2 (Correct answer)

Correct answer: Condition 2

Condition 2 applies when there are exposed live parts on one side and grounded parts (such as a concrete/masonry wall) on the other side.

Question 2: What is the maximum standard size inverse-time circuit breaker that can be used for branch-circuit, short-circuit, and ground-fault protection for a 50-hp, 460-volt, 3-phase motor?

175 A (Correct answer)
150 A
125 A
200 A

Correct answer: 175 A

The motor's FLC from Table 430.250 is 65A. Per Table 430.52, the maximum percentage for an inverse-time breaker is 250% of the FLC. The calculation is 65A * 2.50 = 162.5A. Since 162.5A is not a standard size, NEC 430.52(C)(1) Exception No. 1 permits rounding up to the next standard size, which is 175A.

Question 3: A 480V delta–wye transformer secondary supplies a 208Y/120V panelboard. The neutral conductor on the secondary is derived from:

The wye-connected secondary center point (Correct answer)
The primary overcurrent device
A separately derived grounding electrode
The delta primary winding center tap

Correct answer: The wye-connected secondary center point

In a wye-configured secondary, the neutral is the center (star) point of the three wye windings connected to ground.

Question 4: The 'kVA' rating on a transformer nameplate represents:

The maximum continuous real power output
The apparent power capacity under rated conditions (Correct answer)
The no-load core loss in volt-amperes
The transformer's short-circuit withstand rating

Correct answer: The apparent power capacity under rated conditions

kVA is the product of rated voltage and rated current (apparent power), not accounting for load power factor.

Question 5: In a commercial occupancy, the NEC requires that luminaires installed in a clothes closet must maintain what minimum clearance from the storage area?

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

Correct answer: 12 inches

NEC 410.16(C) requires incandescent and LED luminaires to maintain at least 12 inches of clearance from the defined storage space in closets.

Question 6: According to NEC Article 700, what is the maximum time permitted for an emergency system to automatically connect to its power source after an interruption of the normal supply?

30 seconds
2 minutes
10 seconds (Correct answer)
60 seconds

Correct answer: 10 seconds

NEC 700.12 states that emergency systems must have automatic transfer equipment that restores power within 10 seconds of a normal power failure. This rapid transfer is critical for life safety systems like egress lighting and fire alarms.

Question 7: Per NEC 300.5, direct burial cable must be installed at what minimum depth under a commercial parking lot or driveway?

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

Correct answer: 24 inches

NEC Table 300.5 requires a minimum burial depth of 24 inches under commercial driveways and parking areas for direct burial conductors.

Question 8: What does NEC 240.4 require regarding overcurrent protection for conductors?

Any available overcurrent device can be used as long as it trips before conductor melts
Conductors must be protected at their ampacity or the next standard overcurrent device size up if within certain limits (Correct answer)
Overcurrent devices must be sized at 125% of conductor ampacity
Conductors must always be protected at exactly their rated ampacity

Correct answer: Conductors must be protected at their ampacity or the next standard overcurrent device size up if within certain limits

NEC 240.4 requires conductors to be protected at their ampacity; however, where the next standard device size is within specific limits (e.g., 800A or less), rounding up to the next standard size is permitted.

Question 9: In a commercial garage with adequate ventilation per NEC 511.3(B), the area above 18 inches from the floor is classified as:

Class I, Division 1
Unclassified (Correct answer)
Class II, Division 2
Class I, Division 2

Correct answer: Unclassified

When a commercial garage has adequate ventilation, the area above 18 inches from the floor is considered unclassified per NEC 511.3(B).

Question 10: What is the minimum burial depth for a ground rod electrode per NEC 250.53(G)?

8 feet (Correct answer)
10 feet
4 feet
6 feet

Correct answer: 8 feet

NEC 250.53(G) requires ground rods to be driven to a depth of at least 8 feet to ensure adequate earth contact.

Question 11: A feeder supplies two motors. The largest motor is protected by a 150A branch-circuit breaker, and the second motor has an FLC of 40A. What is the maximum size circuit breaker allowed for the feeder protection?

175 A (Correct answer)
225 A
190 A
200 A

Correct answer: 175 A

Per NEC 430.62(A), the feeder overcurrent device rating shall not be greater than the largest branch-circuit protective device rating plus the sum of the FLCs of the other motors on the feeder. The calculation is 150A (largest branch OCPD) + 40A (FLC of other motor) = 190A. Since 190A is not a standard size, the next lower standard size of 175A must be used.

Question 12: What is the maximum time permitted for a Legally Required Standby System to be automatically connected to its power source after a normal power failure?

60 seconds (Correct answer)
5 minutes
30 seconds
10 seconds

Correct answer: 60 seconds

NEC 701.12 specifies that legally required standby systems must have automatic transfer equipment that restores power within 60 seconds of a normal power failure. These systems support critical operations like ventilation and smoke removal, which are important but less immediately life-threatening than those on the emergency system.

Question 13: Per NEC 430.52, the maximum rating of an inverse-time circuit breaker used as motor branch-circuit protection for a Design B squirrel-cage motor is:

400% of FLC
250% of FLC (Correct answer)
200% of FLC
150% of FLC

Correct answer: 250% of FLC

NEC Table 430.52 allows inverse-time breakers to be rated up to 250% of the motor FLC for Design B squirrel-cage motors.

Question 14: In a health care facility's critical care area, a ground fault circuit interrupter (GFCI) is generally NOT used on receptacles because:

GFCI devices are too expensive for hospital budgets
NEC prohibits GFCI in any health care setting
GFCI nuisance tripping could interrupt power to life-critical equipment (Correct answer)
Critical care areas always have isolated power systems making GFCI redundant

Correct answer: GFCI nuisance tripping could interrupt power to life-critical equipment

NEC 517.20 allows isolated power systems or GFCI protection in wet procedure locations, but GFCI nuisance tripping on critical care equipment is a life-safety concern.

Question 15: What is the maximum unprotected length of service entrance conductors permitted inside a building before reaching the service disconnecting means per NEC 230.70 and 230.6?

No limit if in conduit
25 feet
Conductors must be considered outside even when encased in concrete or masonry (Correct answer)
10 feet

Correct answer: Conductors must be considered outside even when encased in concrete or masonry

NEC 230.6 permits service conductors encased in 2 inches of concrete or masonry to be considered outside the building, effectively allowing them to reach the disconnect without the 'inside' restrictions.

Question 16: Per NEC 430.62(A), the feeder overcurrent protective device for a group of motors shall not exceed the rating of:

The sum of all individual branch-circuit device ratings
The largest permitted branch-circuit device for the biggest motor, plus the FLA of all other motors (Correct answer)
250% of the largest motor's FLA alone
125% of the total FLA of all motors combined

Correct answer: The largest permitted branch-circuit device for the biggest motor, plus the FLA of all other motors

NEC 430.62(A) limits the feeder overcurrent device to the maximum permitted branch-circuit protective device rating for the largest motor plus the FLA of all other motors.

Question 17: Per NEC 430.53(D), when several motors are connected to a single branch circuit, the branch-circuit short-circuit protective device rating shall not exceed the maximum permitted value for:

The motor requiring the smallest maximum protective device rating (Correct answer)
The motor with the highest FLA in the group
The average protective device rating across all motors
The motor with the highest locked rotor current

Correct answer: The motor requiring the smallest maximum protective device rating

NEC 430.53(D) requires the branch-circuit protective device to not exceed the maximum permitted rating for the most restrictively protected motor in the group.

Question 18: Intermediate Metal Conduit (IMC) is permitted to be used as an equipment grounding conductor under which condition?

Never — a separate EGC is always required
Only indoors
Only when bonded at both ends with locknuts
Only with listed fittings installed per manufacturer instructions (Correct answer)

Correct answer: Only with listed fittings installed per manufacturer instructions

NEC 250.118(4) permits IMC to serve as an EGC when installed with listed fittings according to the manufacturer's instructions.

Question 19: A commercial inspector finds emergency generator feeder conductors in the same conduit as normal-power feeders. This is:

A violation of NEC 700.10 (Correct answer)
Acceptable if the emergency feeder is larger
Acceptable if the conduit is metallic
Acceptable if THHN conductors are used

Correct answer: A violation of NEC 700.10

NEC 700.10(B) requires emergency system wiring to be kept entirely independent of other wiring in separate conduits, cables, or raceways.

Question 20: What is the minimum ampacity required for the branch-circuit conductors supplying a single 25-hp, 460-volt, 3-phase, continuous-duty motor?

37.4 A
51 A
42.5 A (Correct answer)
34 A

Correct answer: 42.5 A

First, find the motor's Full-Load Current (FLC) from NEC Table 430.250, which is 34A for a 25-hp, 460V, 3-phase motor. Per NEC 430.22, conductors for a single continuous-duty motor must have an ampacity of at least 125% of the motor FLC. The calculation is 34A * 1.25 = 42.5A.

Question 21: What does the NEC require for grounding electrode conductors at a commercial service entrance that uses a metal water pipe as a grounding electrode?

The pipe must be bonded with a 6 AWG conductor only
A supplemental electrode must also be installed (Correct answer)
No supplemental electrode is needed if the pipe is 3/4 inch or larger
The conductor must be at least 4 AWG copper

Correct answer: A supplemental electrode must also be installed

NEC 250.53(D)(2) requires a supplemental grounding electrode when a metal water pipe is used as a grounding electrode.

Question 22: Under NEC 517.13, branch circuits serving patient care vicinities must have an equipment grounding conductor that is:

A metallic conduit system serving as the sole grounding path
A bare copper conductor sized per 250.122
A separate ground rod at each patient bed location
An insulated copper conductor run with the circuit conductors (Correct answer)

Correct answer: An insulated copper conductor run with the circuit conductors

NEC 517.13 requires an insulated copper equipment grounding conductor run with the circuit conductors in patient care vicinities, not relying solely on the raceway.

Question 23: An inspector is reviewing plans for a commercial building addition. The plans show a new feeder tapped from an existing panelboard busbar using a tap conductor that is smaller than the feeder conductors. Under what conditions does the NEC permit this tap?

The tap is only permitted if the existing panel is rated for 200A or more
Taps from panelboard busbars are never permitted; only lugs may be used
The tap is permitted if it follows NEC 240.21 tap rules, such as the 10-foot or 25-foot tap rule with appropriate termination at a protected panel (Correct answer)
Tap conductors are permitted at any size as long as they are in conduit

Correct answer: The tap is permitted if it follows NEC 240.21 tap rules, such as the 10-foot or 25-foot tap rule with appropriate termination at a protected panel

NEC 240.21 provides tap rules that allow unprotected conductors for limited distances (10 ft, 25 ft, or transformer secondary) if specific conditions are met.

Question 24: A continuous-duty motor has a nameplate current rating of 40A and a service factor of 1.15. What is the maximum rating for a separate overload protection device for this motor?

40 A
60 A
46 A
50 A (Correct answer)

Correct answer: 50 A

According to NEC 430.32(A)(1), for a motor with a service factor of 1.15 or greater, the separate overload device shall be selected to trip at no more than 125% of the motor nameplate current rating. The calculation is 40A * 1.25 = 50A. This protects the motor from sustained overcurrents without nuisance tripping.

Question 25: In a commercial high-rise, cables are installed in a cable tray in a ventilated space. Which ampacity table from NEC Article 310 would apply to single conductors installed in cable tray without a maintained spacing?

Table 310.16 — same as conduit
NEC 392.80(A) — cable tray provisions govern (Correct answer)
Table 310.17 — single conductors in free air
Table 310.60 — for medium voltage only

Correct answer: NEC 392.80(A) — cable tray provisions govern

NEC 392.80 governs ampacity for conductors and cables in cable trays; single conductors in cable tray without maintained spacing use the cable tray provisions, not Table 310.16 or 310.17.

Question 26: A commercial warehouse has 200,000 VA of general lighting load. What is the demand load after applying NEC Table 220.42 factors for warehouses?

112,500 VA
125,000 VA (Correct answer)
150,000 VA
100,000 VA

Correct answer: 125,000 VA

For 'all other' occupancies: first 50,000 VA × 100% = 50,000 VA, plus 150,000 VA × 50% = 75,000 VA, totaling 125,000 VA.

Question 27: When reviewing plans, you notice that a feeder is undersized for the load it is serving. What is the correct action?

Ignore the issue if it is only slightly undersized
Approve the plans but note the issue for the field inspector
Reject the plans and request corrections (Correct answer)
Approve the plans if the contractor provides a justification

Correct answer: Reject the plans and request corrections

An undersized feeder poses a significant safety hazard, as it can lead to overheating, fire, and equipment damage due to excessive current draw. As an electrical inspector, your duty is to ensure all designs comply with the National Electrical Code (NEC) and safety standards. Approving such a plan, even with a note, would be a dereliction of this duty and could result in dangerous installations.

Question 28: NEC 517.13 requires that patient care areas in healthcare facilities have what special grounding provision for receptacles and fixed equipment?

Double-pole GFCI protection
Isolated ground receptacles throughout
AFCI protection on all circuits
An insulated equipment grounding conductor in addition to the metallic raceway path (Correct answer)

Correct answer: An insulated equipment grounding conductor in addition to the metallic raceway path

NEC 517.13 mandates a redundant grounding path: both the metal raceway and an insulated EGC must be present to ensure continuity in patient care areas.

Question 29: Under NEC Article 511, in a commercial repair garage, the area within 18 inches above floor level is classified as:

Unclassified if ventilated
Class I, Division 1
Class II, Division 1
Class I, Division 2 (Correct answer)

Correct answer: Class I, Division 2

NEC 511.3 classifies the area up to 18 inches above floor level in commercial garages as Class I, Division 2 due to heavier-than-air gasoline vapors.

Question 30: When inspecting a commercial occupancy's air-conditioning system with a hermetic refrigerant motor-compressor, the branch circuit overcurrent protection is permitted to be sized up to:

175% of the nameplate rated-load current
300% of the nameplate rated-load current
225% of the nameplate rated-load current (Correct answer)
125% of the nameplate rated-load current

Correct answer: 225% of the nameplate rated-load current

NEC 440.22(A) allows the branch circuit overcurrent protection for a hermetic refrigerant motor-compressor to be sized up to 225% of the nameplate rated-load current.

Question 31: A 10 AWG THHN conductor in a 90°C rated conduit system has a terminal rated at 60°C. What ampacity column governs the calculation?

90°C column — 40A
60°C column — 30A (Correct answer)
90°C derated to 75°C — 33A
75°C column — 35A

Correct answer: 60°C column — 30A

Per NEC 110.14(C)(1), the conductor ampacity cannot exceed the terminal's temperature rating; with a 60°C terminal, the 60°C column (30A for 10 AWG) governs.

Question 32: A contractor installs a commercial fire alarm system panel in an electrical room and places it 12 inches from an existing panelboard. What NEC concern should the inspector raise?

No concern; NFPA 72 supersedes NEC working space requirements
Fire alarm panels are prohibited in electrical rooms under NEC 760
The 12-inch separation meets NEC 110.26(A)(3) clearance for dedicated space
Fire alarm panels must not reduce the required working space in front of electrical equipment per NEC 110.26 (Correct answer)

Correct answer: Fire alarm panels must not reduce the required working space in front of electrical equipment per NEC 110.26

NEC 110.26(A) working space requirements must be maintained; installing equipment that encroaches on the required 3-foot depth in front of a panelboard is a violation.

Question 33: Which of the following is listed in NEC 430.109(A) as an acceptable type of motor disconnecting means?

Branch circuit breaker on a general lighting panelboard for a 30 HP motor
General-use toggle switch for any motor size
Motor circuit switch rated in horsepower (Correct answer)
Attachment plug and receptacle for motors over 2 HP on 300V circuits

Correct answer: Motor circuit switch rated in horsepower

NEC 430.109(A) lists motor circuit switches rated in horsepower as an approved type of disconnecting means for motor circuits.

Question 34: An E2 inspector observes that a 277V fluorescent lighting circuit has no GFCI protection in a commercial kitchen wet location. Which code section applies?

NEC 215.9 mandates AFCI for all lighting circuits
NEC 230.95 requires GFPE for services over 150V
NEC 210.8(B) only covers 120V receptacles in commercial kitchens
NEC 210.8(B) requires GFCI for 277V circuits in commercial wet locations (Correct answer)

Correct answer: NEC 210.8(B) requires GFCI for 277V circuits in commercial wet locations

NEC 210.8(B) requires GFCI protection for personnel in commercial kitchens, including 277V circuits used in wet locations.

Question 35: Which motor nameplate data item is used to determine the correct overload protection size per NEC 430.32?

Horsepower and locked-rotor current
NEMA design letter and frame size
Service factor and nameplate current (Correct answer)
Torque class and efficiency rating

Correct answer: Service factor and nameplate current

NEC 430.32 bases overload sizing on the motor's nameplate full-load amperes and service factor (or temperature rise).

Question 36: A transformer secondary conductor run in a separate raceway from the transformer to the first overcurrent device must be protected at its ampacity unless:

It is copper and enclosed in conduit
It meets the physical protection requirements of NEC 240.21(C) (Correct answer)
It is shorter than 10 feet
It is sized at 200% of the OCPD rating

Correct answer: It meets the physical protection requirements of NEC 240.21(C)

NEC 240.21(C) provides tap rules allowing transformer secondary conductors to run without overcurrent protection at the transformer if specific length, termination, and conductor sizing conditions are met.

Question 37: What type of overcurrent protection device is typically used to protect a motor circuit?

Non-time-delay fuse
Circuit breaker
Ground-fault circuit interrupter (GFCI)
Time-delay fuse (Correct answer)

Correct answer: Time-delay fuse

Time-delay fuses are used in motor circuits to allow the motor to handle its inrush current (starting current) without tripping immediately. This is crucial for motors, which draw higher current during startup.

Question 38: A commercial parking lot has 20 pole-mounted luminaires each rated 400W. What load must be included in the service calculation?

10,000 VA at 125% (Correct answer)
12,000 VA at 150%
8,000 VA at 100%
8,000 VA at 80%

Correct answer: 10,000 VA at 125%

Outdoor lighting operates continuously; 20 × 400W = 8,000W × 125% = 10,000 VA per NEC 215.2 continuous load rules.

Question 39: What is the allowable ampacity of a 3 AWG THWN copper conductor operating at 75°C?

115 A
110 A
100 A (Correct answer)
85 A

Correct answer: 100 A

Using NEC Table 310.16, find the row for '3' under the AWG size column. Then, move across to the 'Copper' section and down the column for 75°C (which covers THWN insulation). The value listed is 100 amperes.

Question 40: Which wiring method is specifically listed for use in concrete encasement?

Intermediate Metal Conduit (IMC)
Rigid Metal Conduit (RMC) (Correct answer)
Flexible Metal Conduit (FMC)
Electrical Metallic Tubing (EMT)

Correct answer: Rigid Metal Conduit (RMC)

RMC (Rigid Metal Conduit) is permitted for direct burial and encasement in concrete per NEC 344.10.

Question 41: Intrinsically safe equipment is defined as equipment that:

Is housed in an explosion-proof enclosure
Is listed for Division 2 locations only
Cannot produce sparks or thermal effects capable of igniting a hazardous mixture (Correct answer)
Uses pressurized enclosures to prevent hazardous atmosphere entry

Correct answer: Cannot produce sparks or thermal effects capable of igniting a hazardous mixture

Intrinsically safe equipment is incapable of releasing sufficient electrical or thermal energy under normal or abnormal conditions to cause ignition of a specific hazardous atmospheric mixture.

Question 42: What is the minimum ampacity required for a service entrance conductor supplying a single commercial occupancy with a calculated load of 175 amperes?

225 amperes
200 amperes
175 amperes (Correct answer)
150 amperes

Correct answer: 175 amperes

Service conductors must have an ampacity not less than the calculated load per NEC 230.42.

Question 43: In a commercial kitchen, a dishwasher is hardwired to a 20-ampere, 120-volt circuit. The NEC requires this circuit to be protected by a:

GFCI with 4mA trip threshold
AFCI breaker
Standard overcurrent device only
Standard GFCI breaker (Correct answer)

Correct answer: Standard GFCI breaker

NEC 210.8(B) requires GFCI protection for commercial kitchen equipment in areas where water is present.

Question 44: Flexible connections in Class I, Division 1 locations must use which type of flexible fitting?

Listed flexible fittings approved for the location (Correct answer)
Standard flexible metallic conduit
Liquidtight flexible nonmetallic conduit
PVC-jacketed flexible conduit

Correct answer: Listed flexible fittings approved for the location

Flexible connections in Class I, Division 1 locations must use listed flexible fittings specifically approved for use in that classified location.

Question 45: Under NEC 430.87, when two or more motors are served from the same controller, each motor must have:

Individual overload protection (Correct answer)
Separate grounding electrode conductors
Its own branch-circuit fuse
A common disconnect within sight

Correct answer: Individual overload protection

NEC 430.87 states that each motor must be protected by individual overload devices even when served from a common controller.

Question 46: A commercial building has 150 general-purpose duplex receptacles that are not used for general illumination. What is the calculated load for these receptacles after applying demand factors?

13,500 VA
10,000 VA
18,500 VA (Correct answer)
27,000 VA

Correct answer: 18,500 VA

According to NEC 220.14(I), each receptacle outlet is calculated at 180 VA. The total load is 150 * 180 VA = 27,000 VA. Per Table 220.44, the first 10 kVA is at 100% and the remainder is at 50%, resulting in a calculated load of 18,500 VA (10,000 + (17,000 * 0.5)).

Question 47: According to the NEC, what is the minimum clearance required above a switchboard in a commercial installation?

6 feet (Correct answer)
6.5 feet
8 feet
3 feet

Correct answer: 6 feet

NEC 110.26(A)(1) requires a minimum of 6 feet of headroom above electrical equipment such as switchboards.

Question 48: A 20 HP, 460V, 3-phase motor has a table FLA of 27A. What is the minimum branch circuit conductor ampacity required by NEC 430.22?

40.5A
33.75A (Correct answer)
31.1A
27A

Correct answer: 33.75A

125% of 27A = 33.75A is the minimum conductor ampacity per NEC 430.22 for continuous-duty operation.

Question 49: In a commercial office building, a multiwire branch circuit supplies power to several cubicles. According to NEC 210.4(B), what is required at the point where this branch circuit originates?

An overcurrent device rated for the sum of the connected loads.
A means to individually disconnect each ungrounded conductor.
A means that will simultaneously disconnect all ungrounded conductors. (Correct answer)
A single-pole circuit breaker for each ungrounded conductor.

Correct answer: A means that will simultaneously disconnect all ungrounded conductors.

NEC 210.4(B) requires that each multiwire branch circuit be provided with a means that will simultaneously disconnect all ungrounded conductors at the point where the branch circuit originates. This is a critical safety measure to prevent personnel from working on a circuit they believe is de-energized when one of the ungrounded conductors is still live. This is typically achieved with a multi-pole circuit breaker or single-pole breakers with an identified handle tie.

Question 50: When inspecting a commercial pool pump motor installation, which bonding requirement is unique compared to standard motor installations?

Bonding is not required if GFCI protection is provided
The pool pump motor requires a dedicated grounding rod
All metal parts within 5 feet of the pool, including the motor, must be bonded together with a solid copper conductor no smaller than 8 AWG (Correct answer)
The motor frame must be bonded to the equipment grounding conductor only

Correct answer: All metal parts within 5 feet of the pool, including the motor, must be bonded together with a solid copper conductor no smaller than 8 AWG

NEC 680.26 requires all metal parts within 5 feet of the pool water surface to be bonded together using a solid copper bonding conductor not smaller than 8 AWG solid.

Question 51: During a commercial building inspection, you observe a feeder supplying a separate building. Which NEC article must be consulted to ensure the grounding and bonding requirements at the separate building are met?

Article 210 - Branch Circuits
Article 240 - Overcurrent Protection
Article 250 - Grounding and Bonding (Correct answer)
Article 230 - Services

Correct answer: Article 250 - Grounding and Bonding

NEC 215.6 requires that where a feeder supplies a separate building or structure, the grounding and bonding requirements of Article 250, specifically 250.32, shall apply. This section details how to establish a grounding electrode system and handle the equipment grounding conductors and system bonding at the separate structure.

Question 52: Per NEC 430.53(A), motors of what maximum horsepower rating or less may be connected to a general-purpose branch circuit without individual overcurrent protection, when the circuit is protected at not more than 20 amperes?

1 HP (Correct answer)
1/2 HP
1/4 HP
2 HP

Correct answer: 1 HP

NEC 430.53(A) permits motors of 1 HP or less to be connected to a general-purpose branch circuit without individual motor branch-circuit protection when specified conditions are met.

Question 53: Equipment installed in a Class I hazardous location must be marked to show which information as required by NEC 500.8?

Voltage rating and ampacity only
Conduit fill percentage and conductor insulation type
Class, Division or Zone, Group, and temperature class (T-code) (Correct answer)
Manufacturer name and UL listing number only

Correct answer: Class, Division or Zone, Group, and temperature class (T-code)

NEC 500.8 requires equipment markings to include the Class, Division or Zone, Group, and temperature class to ensure compatibility with the specific hazard.

Question 54: For a 480Y/277-volt, 3-phase, 4-wire service with a calculated load of 500 amperes on the ungrounded conductors, what is the calculated neutral load?

200 A
350 A
500 A
410 A (Correct answer)

Correct answer: 410 A

Per NEC 220.61, the first 200 amperes of neutral load is calculated at 100%. The remainder of the load above 200 amperes can be reduced by a demand factor of 70%. The calculation is 200 A + ((500 A - 200 A) * 0.70) = 200 A + 210 A = 410 A.

Question 55: A generator used as the alternate power source for an emergency system must be provided with selective coordination from the emergency panel to the transfer switch for fault currents lasting:

1 second and longer
10 seconds and longer
0.5 second and longer
0.1 second and longer (Correct answer)

Correct answer: 0.1 second and longer

NEC 700.32 requires selective coordination of overcurrent devices for fault durations of 0.1 second and longer.

Question 56: During inspection of a commercial kitchen, an inspector finds 120V receptacles within 6 feet of a sink without GFCI protection. According to NEC 210.8(B), this is:

Compliant if a GFCI breaker is provided at the panel
Not a violation since commercial kitchens are exempt from NEC 210.8
Compliant if the receptacles are not within 3 feet of the sink edge
A violation; GFCI protection is required for all receptacles in commercial kitchens (Correct answer)

Correct answer: A violation; GFCI protection is required for all receptacles in commercial kitchens

NEC 210.8(B)(2) requires GFCI protection for all receptacles in commercial kitchens regardless of distance from water sources.

Question 57: The disconnecting means for a motor controller and the motor shall have an ampere rating of at least what percentage of the motor's full-load current?

125%
100%
115% (Correct answer)
80%

Correct answer: 115%

NEC 430.110(A) requires that the disconnecting means have an ampere rating of at least 115% of the motor's full-load current rating as determined by the FLC tables in Article 430. This ensures the disconnect can safely interrupt the locked-rotor current of the motor. It must also have a sufficient horsepower rating per 430.109.

Question 58: A 480V, 3-phase transformer feeding a 120/208V panelboard in a commercial building must have its secondary protected at no more than what percentage of the transformer's rated secondary current when using a standard fuse?

250%
100%
125% (Correct answer)
300%

Correct answer: 125%

NEC 450.3(B) allows secondary overcurrent protection up to 125% of the transformer's rated secondary current for a supervised installation.

Question 59: Per NEC Table 220.55, what is the maximum demand used when a commercial establishment has a single household cooking unit rated 12 kW?

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

Correct answer: 8 kW

NEC Table 220.55 permits a maximum demand of 8 kW for a single range rated 12 kW or less.

Question 60: A feeder supplies three motors with FLCs of 50A, 30A, and 15A. What is the minimum required ampacity for the feeder conductors?

118.75 A
107.5 A (Correct answer)
142.5 A
95 A

Correct answer: 107.5 A

NEC 430.24 requires the feeder conductor ampacity to be the sum of all motor FLCs plus 25% of the largest motor's FLC. The calculation is (50A * 1.25) + 30A + 15A = 62.5A + 30A + 15A = 107.5A. The conductors must have an ampacity of at least 107.5A.

Question 61: A commercial building's 277/480V lighting panelboard serves fluorescent fixtures with electronic ballasts. The inspector notes the neutral is undersized. Why is this a concern?

Undersized neutrals only matter in single-phase systems
277V systems do not require a neutral conductor
The neutral must be sized at 200% for all 480V systems
Electronic ballasts generate 3rd-order harmonics that add on the neutral, potentially causing it to carry more current than the phase conductors (Correct answer)

Correct answer: Electronic ballasts generate 3rd-order harmonics that add on the neutral, potentially causing it to carry more current than the phase conductors

Electronic ballasts and nonlinear loads produce triplen harmonics that accumulate on the neutral conductor, requiring it to be upsized per NEC 310.15(E).

Question 62: For 'all other' commercial occupancies per NEC Table 220.42, what demand factor applies to lighting loads exceeding 50,000 VA?

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

Correct answer: 50%

NEC Table 220.42 allows a 50% demand factor on lighting loads over 50,000 VA for most commercial occupancies.

Question 63: Which NEC table provides full-load current values for single-phase AC motors used for conductor and protection sizing?

Table 430.249
Table 430.250
Table 430.248 (Correct answer)
Table 430.247

Correct answer: Table 430.248

Table 430.248 lists FLA values for single-phase AC motors, which are used in place of nameplate values for conductor and overcurrent device sizing.

Question 64: Which protection concept uses oil immersion to prevent ignition of a surrounding hazardous atmosphere?

Oil immersion (Ex o) (Correct answer)
Intrinsic safety (Ex i)
Encapsulation (Ex m)
Pressurization (Ex p)

Correct answer: Oil immersion (Ex o)

Oil immersion (Ex o) is a protection technique where electrical equipment or parts of equipment are submerged in oil to prevent ignition of the surrounding atmosphere.

Question 65: In a marina covered by NEC Article 555, shore power receptacles rated 30 amperes or less must be protected by:

Isolation transformers at each slip
Standard circuit breakers with ground fault protection only at the panel
GFCI protection (Correct answer)
Listed marine power outlets with leakage current protection

Correct answer: GFCI protection

NEC 555.19(B)(1) requires GFCI protection for 15A and 20A, 125V shore power receptacles at marinas, and leakage current interrupters for 30A and larger.

Question 66: An E2 inspector is reviewing a commercial installation where 6 AWG THHN conductors are in a conduit exposed to direct sunlight on a rooftop. What adder to ambient temperature is required per NEC 310.15(B)(2)?

No adder is required for conduit on a rooftop
17°C added to the ambient temperature (Correct answer)
10°C added to the ambient temperature
33°C added to the ambient temperature

Correct answer: 17°C added to the ambient temperature

NEC 310.15(B)(2) requires a 17°C temperature adder for raceways exposed to direct sunlight on or above rooftops when within 7/8 inch to 3½ inches above the roof.

Question 67: A motor feeder supplies three motors with table FLA values of 40A, 25A, and 15A. What is the minimum feeder conductor ampacity per NEC 430.24?

90A (Correct answer)
100A
110A
80A

Correct answer: 90A

Feeder ampacity = (1.25 × 40A) + 25A + 15A = 50A + 25A + 15A = 90A per NEC 430.24.

Question 68: Per NEC 430.52(C)(2), if the maximum standard inverse time breaker size cannot carry the motor's starting current, the breaker rating may be increased to a maximum of:

400% of FLA (Correct answer)
700% of FLA
600% of FLA
300% of FLA

Correct answer: 400% of FLA

NEC 430.52(C)(2) allows the inverse time breaker to be increased to a maximum of 400% of FLA when the standard 250% cannot handle motor starting current.

Question 69: What is the minimum show window lighting load per linear foot required in commercial load calculations per NEC 220.14(G)?

180 VA
100 VA
200 VA (Correct answer)
150 VA

Correct answer: 200 VA

NEC 220.14(G) requires a minimum of 200 VA per linear foot of show window for load calculations.

Question 70: What is the primary purpose of grounding in a commercial electrical system?

To ensure proper voltage levels
To prevent overloading of circuits
To provide a path for lightning strikes
To reduce the risk of electric shock and equipment damage (Correct answer)

Correct answer: To reduce the risk of electric shock and equipment damage

Grounding provides a low-resistance path to dissipate fault current, protecting personnel from electric shock and preventing equipment damage. It is a critical safety requirement in all electrical installations.

Question 71: In an aircraft hangar per NEC Article 513, the area within 5 feet horizontally from aircraft power plants is classified as:

Class I, Division 2 (Correct answer)
Unclassified with proper ventilation
Class II, Division 2
Class I, Division 1

Correct answer: Class I, Division 2

NEC 513.3 classifies areas within 5 feet horizontally from aircraft power plants and fuel tanks up to 5 feet above the upper surface as Class I, Division 2.

Question 72: A feeder serves a panelboard in a commercial building. The total noncontinuous load is 60A and the continuous load is 40A. What is the minimum feeder overcurrent device rating?

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

Correct answer: 100 amperes

Per NEC 215.3: (40A × 1.25) + (60A × 1.0) = 50A + 60A = 110A minimum; next standard size up is 125A, but 100A is not less — the correct calculation yields 110A requiring a 110A or next standard 125A device, making 100A incorrect; minimum standard size at or above 110A is 125A.

Question 73: In a Class I hazardous location, which type of luminaire (light fixture) is required in Division 1 areas?

Standard enclosed luminaire with GFCI protection
Explosion-proof luminaire listed for Class I, Division 1 (Correct answer)
Vapor-tight luminaire
Dust-tight luminaire

Correct answer: Explosion-proof luminaire listed for Class I, Division 1

Luminaires in Class I, Division 1 locations must be explosion-proof and specifically listed for Class I, Division 1 use.

Question 74: Per NEC 430.110(A), the ampere rating of the motor circuit disconnecting means must be at least what percentage of the motor's full-load current rating?

100%
150%
125%
115% (Correct answer)

Correct answer: 115%

NEC 430.110(A) requires the motor disconnecting means to have an ampere rating of at least 115% of the motor's full-load current rating.

Question 75: A 25,000 sq ft office building is being permitted. What is the minimum general lighting load before applying any demand factors?

50,000 VA
87,500 VA (Correct answer)
75,000 VA
125,000 VA

Correct answer: 87,500 VA

Office occupancies use 3.5 VA/sq ft per NEC Table 220.12, so 25,000 × 3.5 = 87,500 VA.

Question 76: An inspector reviews plans where the designer omitted the 40-ton air conditioning load because the electric heating load is larger. Under what condition is this acceptable?

Acceptable only if the AC load is under 10 kW
Acceptable when heating and AC are non-coincident loads per NEC 220.60 (Correct answer)
Acceptable only if approved by the utility company
Never acceptable; both loads must always be included at 100%

Correct answer: Acceptable when heating and AC are non-coincident loads per NEC 220.60

NEC 220.60 permits omitting the smaller of two non-coincident loads when they cannot reasonably operate simultaneously.

Question 77: Which of the following fixed wiring methods is generally permitted in a theater's auditorium classified as an assembly occupancy under NEC Article 518, provided it is not required to be of fire-rated construction?

Nonmetallic-sheathed cable (Type NM) (Correct answer)
Concealed knob-and-tube wiring
Service-entrance cable (Type SE)
Open wiring on insulators

Correct answer: Nonmetallic-sheathed cable (Type NM)

NEC 518.4(C) permits the use of wiring methods from Chapters 1 through 4, including nonmetallic-sheathed cable, in areas of an assembly occupancy that are not required by the building code to have a fire-rated construction. However, 518.4(A) requires more robust wiring methods like metal raceways for areas that must be fire-rated.

Question 78: Under NEC 700, which of the following is NOT an acceptable alternate power source for an emergency system?

Separate service from a different utility substation on the same grid section (Correct answer)
Stored electrical energy (batteries)
Generator set
Unit equipment with integral battery

Correct answer: Separate service from a different utility substation on the same grid section

A separate service from the same utility grid section does not qualify because a single utility failure could knock out both sources; true independence is required.

Question 79: The Essential Electrical System (EES) for a hospital is composed of which three separate branches?

Normal, Alternate, and Isolated
Life Safety, Critical, and Equipment (Correct answer)
Emergency, Standby, and Optional
Patient Care, General, and Critical

Correct answer: Life Safety, Critical, and Equipment

NEC 517.31 specifies that the Essential Electrical System for hospitals shall be comprised of three separate branches: the life safety, critical, and equipment branches. Each branch serves distinct loads crucial for the safety of patients and staff during a power outage.

Question 80: For an angle pull through a junction box, the distance from the entry raceway to the opposite wall must be at least:

Twelve times the largest raceway
Six times the largest raceway on that row
Four times the trade size of the largest raceway plus the sum of the other raceways on the same wall
Eight times the trade size of the largest raceway plus the sum of the other raceways on the same wall (Correct answer)

Correct answer: Eight times the trade size of the largest raceway plus the sum of the other raceways on the same wall

NEC 314.28(A)(2) requires angle pull dimensions to be at least six times the largest raceway plus the sum of other raceways entering on the same wall — wait, correction: NEC 314.28(A)(2) states six times for angle pulls.

Question 81: Emergency system branch circuits must be kept entirely independent of other wiring with a limited exception for:

Conduit runs that share a common raceway
Transfer switch enclosures only
Common junction boxes shared with normal wiring
Transfer equipment and exit lighting enclosures listed for the purpose (Correct answer)

Correct answer: Transfer equipment and exit lighting enclosures listed for the purpose

NEC 700.10(B) permits emergency wiring to share enclosures only at transfer equipment and exit lighting fixtures listed for the purpose.

ICC E2 Commercial Electrical Inspector

The ICC E2 exam certifies inspectors to perform inspections of electrical system installations and alterations in commercial and industrial buildings, covering services, conductors, wiring methods, and special systems per the NFPA 70 National Electrical Code.

Questions

210 min

Time Limit

75%

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