Electrical Wiring Commercial 18th Edition –
Complete Study Guide and Practice Questions
1. The 18th Edition of the Canadian Electrical Code is
officially titled:
A) C22.2 No. 0-M91
B) CSA C22.1:21
C) NFPA 70E
D) CSA Z462-18
Correct Answer: B
Rationale: CSA C22.1:21 is the Canadian Electrical Code,
Part I, which is the 18th edition (2021 version). The other
options refer to other standards.
2. In commercial wiring, a “branch circuit” is defined as:
A) The conductors between the service point and the
overcurrent device
B) The conductors between the final overcurrent device
and the outlets
C) Any conductor carrying more than 100A
1
,D) Conductors used solely for grounding
Correct Answer: B
Rationale: Section 0 of the CEC defines a branch circuit as
the conductors between the final overcurrent protection
device and the outlets (receptacles, lights, etc.).
3. The minimum clearance for a service mast above a flat
roof with no foot traffic is:
A) 1.0 m
B) 1.5 m
C) 2.0 m
D) 3.0 m
Correct Answer: B
*Rationale: Rule 6-112 requires a minimum clearance of
1.5 m above a roof that is not subject to pedestrian or
vehicle traffic.*
4. In a commercial building, the working space in front of
an electrical panel operating at 600V or less must be at
least:
2
,A) 0.9 m (3 ft)
B) 1.0 m
C) 1.2 m (4 ft)
D) 1.5 m
Correct Answer: A
*Rationale: Rule 2-308 specifies a minimum working
space of 0.9 m (3 ft) in front of electrical equipment
rated 0–750V.*
5. A “tap” conductor in a commercial installation must:
A) Have ampacity at least equal to the load it supplies
B) Be protected by a breaker at both ends
C) Run only in conduit
D) Be copper only
Correct Answer: A
*Rationale: Rule 14-100 allows tap conductors provided
their ampacity meets or exceeds the load they supply,
with length restrictions based on conditions.*
3
, 6. The maximum number of #12 AWG TW conductors
permitted in trade size 53 (2”) EMT before derating is
required:
A) 4
B) 6
C) 9
D) 20
Correct Answer: D
*Rationale: Table 8 (or Rule 12-1014) permits up to 20
#12 TW conductors in 53 EMT. Derating begins when
more than 3 current-carrying conductors are present.*
7. A commercial kitchen with 5 electric ranges is subject to
demand factors from:
A) Table 14
B) Table 15
C) Table 52
D) Table 6
Correct Answer: B
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Complete Study Guide and Practice Questions
1. The 18th Edition of the Canadian Electrical Code is
officially titled:
A) C22.2 No. 0-M91
B) CSA C22.1:21
C) NFPA 70E
D) CSA Z462-18
Correct Answer: B
Rationale: CSA C22.1:21 is the Canadian Electrical Code,
Part I, which is the 18th edition (2021 version). The other
options refer to other standards.
2. In commercial wiring, a “branch circuit” is defined as:
A) The conductors between the service point and the
overcurrent device
B) The conductors between the final overcurrent device
and the outlets
C) Any conductor carrying more than 100A
1
,D) Conductors used solely for grounding
Correct Answer: B
Rationale: Section 0 of the CEC defines a branch circuit as
the conductors between the final overcurrent protection
device and the outlets (receptacles, lights, etc.).
3. The minimum clearance for a service mast above a flat
roof with no foot traffic is:
A) 1.0 m
B) 1.5 m
C) 2.0 m
D) 3.0 m
Correct Answer: B
*Rationale: Rule 6-112 requires a minimum clearance of
1.5 m above a roof that is not subject to pedestrian or
vehicle traffic.*
4. In a commercial building, the working space in front of
an electrical panel operating at 600V or less must be at
least:
2
,A) 0.9 m (3 ft)
B) 1.0 m
C) 1.2 m (4 ft)
D) 1.5 m
Correct Answer: A
*Rationale: Rule 2-308 specifies a minimum working
space of 0.9 m (3 ft) in front of electrical equipment
rated 0–750V.*
5. A “tap” conductor in a commercial installation must:
A) Have ampacity at least equal to the load it supplies
B) Be protected by a breaker at both ends
C) Run only in conduit
D) Be copper only
Correct Answer: A
*Rationale: Rule 14-100 allows tap conductors provided
their ampacity meets or exceeds the load they supply,
with length restrictions based on conditions.*
3
, 6. The maximum number of #12 AWG TW conductors
permitted in trade size 53 (2”) EMT before derating is
required:
A) 4
B) 6
C) 9
D) 20
Correct Answer: D
*Rationale: Table 8 (or Rule 12-1014) permits up to 20
#12 TW conductors in 53 EMT. Derating begins when
more than 3 current-carrying conductors are present.*
7. A commercial kitchen with 5 electric ranges is subject to
demand factors from:
A) Table 14
B) Table 15
C) Table 52
D) Table 6
Correct Answer: B
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