ICC E2 Commercial Electrical Inspector Exam
Questions And Correct Answers (Verified
Answers) Plus Rationales 2026 Q&A | Instant
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1. Which of the following is the maximum allowable voltage drop for
feeders in a commercial building?
A. 2%
B. 3%
C. 5%
D. 10%
B. 3%
Voltage drop should be limited to 3% for feeders to ensure proper
voltage at the load and prevent equipment malfunction.
2. Ground-fault protection of equipment is required for:
A. All lighting circuits
B. Overcurrent devices rated 600 A or less for solidly grounded
wye systems
C. All receptacle outlets
D. Transformers rated less than 50 kVA
B. Overcurrent devices rated 600 A or less for solidly grounded
wye systems
This is mandated by the NEC to reduce the risk of fire and shock
hazards in commercial systems.
,3. In a commercial panelboard, the busbar ampacity must be at
least:
A. 50% of the sum of branch circuits
B. 100% of the sum of branch circuits
C. 125% of the sum of branch circuits
D. 200% of the sum of branch circuits
B. 100% of the sum of branch circuits
The busbar must carry the full load of all connected branch circuits
safely.
4. A 3-phase, 4-wire system has a line-to-line voltage of 480V. What
is the line-to-neutral voltage?
A. 208V
B. 277V
C. 240V
D. 480V
B. 277V
Line-to-neutral voltage in a 480V 3-phase system is calculated as
480 ÷ √3 ≈ 277V.
5. Which conductor material has the highest conductivity?
A. Aluminum
B. Copper
C. Steel
D. Nickel
B. Copper
Copper is widely used in commercial wiring because it has high
conductivity and mechanical strength.
,6. Which of the following is not allowed in a commercial wiring
system?
A. NM cable in a plenum
B. MC cable in exposed locations
C. EMT conduit
D. Rigid metal conduit
A. NM cable in a plenum
Nonmetallic-sheathed (NM) cable is prohibited in plenums due to
fire and smoke safety concerns.
7. The required working clearance in front of electrical equipment
rated 600 volts or less must be at least:
A. 24 inches
B. 30 inches
C. 36 inches
D. 48 inches
C. 36 inches
NEC 110.26 specifies a minimum working space of 36 inches in
front of equipment to allow safe operation and maintenance.
8. A commercial building requires a service disconnecting means.
Where should it be located?
A. In a locked room
B. In a readily accessible location
C. In a mechanical room only
D. Anywhere on the property
B. In a readily accessible location
The service disconnect must be easily accessible in case of
emergency.
, 9. Which of the following is used for short-circuit protection in
commercial lighting circuits?
A. GFCI breaker
B. Circuit breaker
C. Surge protector
D. Isolator switch
B. Circuit breaker
Circuit breakers protect conductors and equipment from excessive
current that could cause damage.
10. In a commercial installation, what is the minimum size
copper grounding electrode conductor for a 200A service?
A. 6 AWG
B. 4 AWG
C. 2 AWG
D. 1/0 AWG
A. 6 AWG
NEC Table 250.66 specifies grounding electrode conductor sizes
based on service rating.
11. What is the primary purpose of arc-fault circuit interrupters
(AFCI)?
A. Prevent shock
B. Protect against overcurrent
C. Detect and prevent electrical fires caused by arcing
D. Control voltage drop
C. Detect and prevent electrical fires caused by arcing
AFCIs are designed to detect arcing faults that could ignite fires.
Questions And Correct Answers (Verified
Answers) Plus Rationales 2026 Q&A | Instant
Download Pdf
1. Which of the following is the maximum allowable voltage drop for
feeders in a commercial building?
A. 2%
B. 3%
C. 5%
D. 10%
B. 3%
Voltage drop should be limited to 3% for feeders to ensure proper
voltage at the load and prevent equipment malfunction.
2. Ground-fault protection of equipment is required for:
A. All lighting circuits
B. Overcurrent devices rated 600 A or less for solidly grounded
wye systems
C. All receptacle outlets
D. Transformers rated less than 50 kVA
B. Overcurrent devices rated 600 A or less for solidly grounded
wye systems
This is mandated by the NEC to reduce the risk of fire and shock
hazards in commercial systems.
,3. In a commercial panelboard, the busbar ampacity must be at
least:
A. 50% of the sum of branch circuits
B. 100% of the sum of branch circuits
C. 125% of the sum of branch circuits
D. 200% of the sum of branch circuits
B. 100% of the sum of branch circuits
The busbar must carry the full load of all connected branch circuits
safely.
4. A 3-phase, 4-wire system has a line-to-line voltage of 480V. What
is the line-to-neutral voltage?
A. 208V
B. 277V
C. 240V
D. 480V
B. 277V
Line-to-neutral voltage in a 480V 3-phase system is calculated as
480 ÷ √3 ≈ 277V.
5. Which conductor material has the highest conductivity?
A. Aluminum
B. Copper
C. Steel
D. Nickel
B. Copper
Copper is widely used in commercial wiring because it has high
conductivity and mechanical strength.
,6. Which of the following is not allowed in a commercial wiring
system?
A. NM cable in a plenum
B. MC cable in exposed locations
C. EMT conduit
D. Rigid metal conduit
A. NM cable in a plenum
Nonmetallic-sheathed (NM) cable is prohibited in plenums due to
fire and smoke safety concerns.
7. The required working clearance in front of electrical equipment
rated 600 volts or less must be at least:
A. 24 inches
B. 30 inches
C. 36 inches
D. 48 inches
C. 36 inches
NEC 110.26 specifies a minimum working space of 36 inches in
front of equipment to allow safe operation and maintenance.
8. A commercial building requires a service disconnecting means.
Where should it be located?
A. In a locked room
B. In a readily accessible location
C. In a mechanical room only
D. Anywhere on the property
B. In a readily accessible location
The service disconnect must be easily accessible in case of
emergency.
, 9. Which of the following is used for short-circuit protection in
commercial lighting circuits?
A. GFCI breaker
B. Circuit breaker
C. Surge protector
D. Isolator switch
B. Circuit breaker
Circuit breakers protect conductors and equipment from excessive
current that could cause damage.
10. In a commercial installation, what is the minimum size
copper grounding electrode conductor for a 200A service?
A. 6 AWG
B. 4 AWG
C. 2 AWG
D. 1/0 AWG
A. 6 AWG
NEC Table 250.66 specifies grounding electrode conductor sizes
based on service rating.
11. What is the primary purpose of arc-fault circuit interrupters
(AFCI)?
A. Prevent shock
B. Protect against overcurrent
C. Detect and prevent electrical fires caused by arcing
D. Control voltage drop
C. Detect and prevent electrical fires caused by arcing
AFCIs are designed to detect arcing faults that could ignite fires.
