C-10 Electrical Part 1 Electrical
License California 2026/2027 — Exam
Questions, Code Calculations
EXAM
1–5: Working Space & Clearances (No Tables)
1. In front of an electrical panel with 0–150 volts to ground, what
is the minimum working depth required?
Answer: 3 feet
Rationale: NEC 110.26(A)(1) states that for 0–150V to ground, the
working space depth is 3 ft. (No table needed.)
2. A panel requires a working width of at least:
Answer: 30 inches
Rationale: NEC 110.26(A)(2) says the width of the working space
must be at least the width of the equipment or 30 inches,
whichever is greater.
3. If equipment has exposed live parts on both sides and is over
600V, the minimum working clearance between them is:
Answer: 4 feet
Rationale: NEC 110.34(A) — for voltages >600V, if accessible
from both sides, the clearance is at least 4 ft.
4. What is the minimum headroom (height) required for electrical
equipment working space?
,Answer: 6 feet 6 inches
Rationale: NEC 110.26(A)(3) — the working space height must be
at least 6½ ft, except for existing dwellings or equipment under
200A.
5. Service conductors (under 600V) above a residential driveway
with no truck traffic need a minimum clearance of:
Answer: 12 feet
Rationale: NEC 230.24(B) — over residential driveways not
subject to truck traffic, clearance is 12 ft.
6–10: Grounding & Bonding (No Tables)
6. A ground rod must be driven to a minimum depth of:
Answer: 8 feet
Rationale: NEC 250.52(A)(5) — the rod must be in contact with
soil for at least 8 ft.
7. If rock prevents driving a full 8-ft ground rod, what is
permitted?
Answer: Drive at a 45° angle or bury horizontally in a trench
Rationale: NEC 250.53(G) — if rock is encountered, the rod may
be buried horizontally in a 30-inch deep trench.
8. The minimum spacing between two ground rods is:
Answer: 6 feet
Rationale: NEC 250.53(A)(3) — rods spaced less than 6 ft are not
considered effective as independent electrodes.
, 9. A concrete-encased electrode (Ufer) must be at least:
Answer: 20 feet long
Rationale: NEC 250.52(A)(3) — rebar or bare copper in concrete
footing must be at least 20 ft in length.
10. The main bonding jumper connects which two parts?
Answer: The grounded conductor (neutral) to the equipment
grounding bus in the service disconnect
Rationale: NEC 250.28 — establishes the effective ground-fault
current path.
11–15: Conductors & Enclosures (No Tables)
11. An electrical junction box must be accessible without:
Answer: Removing any part of the building finish
Rationale: NEC 314.29 — “accessible” means removable without
damaging the building structure.
12. What is the smallest conductor allowed for general residential
branch circuits?
Answer: 14 AWG copper
Rationale: NEC 240.4(D)(3) — 14 AWG copper is protected by a
15A breaker; 12 AWG for 20A circuits.
13. Conductors of different systems (e.g., power and control) can
occupy the same raceway only if:
Answer: All conductors are insulated for the highest voltage
present
Rationale: NEC 300.3(C)(1) — same voltage insulation rating
required, plus grouping every 6 ft.
License California 2026/2027 — Exam
Questions, Code Calculations
EXAM
1–5: Working Space & Clearances (No Tables)
1. In front of an electrical panel with 0–150 volts to ground, what
is the minimum working depth required?
Answer: 3 feet
Rationale: NEC 110.26(A)(1) states that for 0–150V to ground, the
working space depth is 3 ft. (No table needed.)
2. A panel requires a working width of at least:
Answer: 30 inches
Rationale: NEC 110.26(A)(2) says the width of the working space
must be at least the width of the equipment or 30 inches,
whichever is greater.
3. If equipment has exposed live parts on both sides and is over
600V, the minimum working clearance between them is:
Answer: 4 feet
Rationale: NEC 110.34(A) — for voltages >600V, if accessible
from both sides, the clearance is at least 4 ft.
4. What is the minimum headroom (height) required for electrical
equipment working space?
,Answer: 6 feet 6 inches
Rationale: NEC 110.26(A)(3) — the working space height must be
at least 6½ ft, except for existing dwellings or equipment under
200A.
5. Service conductors (under 600V) above a residential driveway
with no truck traffic need a minimum clearance of:
Answer: 12 feet
Rationale: NEC 230.24(B) — over residential driveways not
subject to truck traffic, clearance is 12 ft.
6–10: Grounding & Bonding (No Tables)
6. A ground rod must be driven to a minimum depth of:
Answer: 8 feet
Rationale: NEC 250.52(A)(5) — the rod must be in contact with
soil for at least 8 ft.
7. If rock prevents driving a full 8-ft ground rod, what is
permitted?
Answer: Drive at a 45° angle or bury horizontally in a trench
Rationale: NEC 250.53(G) — if rock is encountered, the rod may
be buried horizontally in a 30-inch deep trench.
8. The minimum spacing between two ground rods is:
Answer: 6 feet
Rationale: NEC 250.53(A)(3) — rods spaced less than 6 ft are not
considered effective as independent electrodes.
, 9. A concrete-encased electrode (Ufer) must be at least:
Answer: 20 feet long
Rationale: NEC 250.52(A)(3) — rebar or bare copper in concrete
footing must be at least 20 ft in length.
10. The main bonding jumper connects which two parts?
Answer: The grounded conductor (neutral) to the equipment
grounding bus in the service disconnect
Rationale: NEC 250.28 — establishes the effective ground-fault
current path.
11–15: Conductors & Enclosures (No Tables)
11. An electrical junction box must be accessible without:
Answer: Removing any part of the building finish
Rationale: NEC 314.29 — “accessible” means removable without
damaging the building structure.
12. What is the smallest conductor allowed for general residential
branch circuits?
Answer: 14 AWG copper
Rationale: NEC 240.4(D)(3) — 14 AWG copper is protected by a
15A breaker; 12 AWG for 20A circuits.
13. Conductors of different systems (e.g., power and control) can
occupy the same raceway only if:
Answer: All conductors are insulated for the highest voltage
present
Rationale: NEC 300.3(C)(1) — same voltage insulation rating
required, plus grouping every 6 ft.
