CALFORNIA C10 ELECTRICAL 2025/2026 QUESTIONS WITH
ANSWERS RATED A+
✔✔One combination that is considered by the NEC to be equivalent to an overcurrent
trip unit is _____.
A-a pole-mounted transformer and overcurrent relay
B-a submersible transformer and overcurrent relay
C-an autotransformer and overcurrent relay
D-a current transformer and overcurrent relay - ✔✔The Correct Answer Is D
NEC Section 240.20(A) states that a current transformer and overcurrent relay shall be
considered equivalent to an overcurrent trip unit.
✔✔When a fuse or circuit breaker is used for circuit protection, the fuse or overcurrent
trip unit shall be connected _____.
A-in series
B-in series and parallel
C-in parallel
D-in tandem - ✔✔The Correct Answer Is A
Fuses or overcurrent trip units (circuit breakers) must be connected in series with
ungrounded conductors so they will open or trip when an overload or ground fault
occurs. NEC Section 240.20(A). The grounding conductor is not provided with
overcurrent protection.
✔✔At what point must a branch-circuit overcurrent protection device be placed in an
electric system?
A-At the equipment ground location.
B-Where the conductor being protected receives its supply.
C-At a tap on the conductor being protected.
D-At the outlet where power is consumed. - ✔✔
✔✔The rating of the overcurrent protective device for a circuit supplying a hermetic
motor-compressor must be at least what percent of the nameplate rated-load current?
A-50 percent
B-75 percent
C-115 percent
D-150 percent - ✔✔The Correct Answer Is C
The ampere rating of the overcurrent protective device must be at least 115 percent of
the nameplate rated-load current of the compressor or branch-circuit selection current,
whichever is greater.
✔✔A multiware branch circuit protected by fuses may supply only _____.
A-half line to line loads and half line to neutral loads
B-half line to neutral loads to full or trip line to other loads
C-line to line loads
D-line to neutral loads - ✔✔The Correct Answer Is D
, NEC Section 210.4(C) requires that multiware branch circuits supply only line to neutral
loads.
✔✔What is the minimum interupting rating of an unmarked branch-circuit fuse?
A-5,000 amperes
B-10,000 amperes
C-15,000 amperes
D-20,000 amperes - ✔✔The Correct Answer Is B
NEMA and UL require fuses to be plainly marked with their characteristics including the
interrupting rating where it is other than 10,000 amperes.
✔✔When designing or installing circuits for diagnostic equipment in health care
facilities, what is the minimum percentage allowed for the momentary ampacity of the
equipment when sizing branch-circuit conductors and the overcurrent protection?
A-25 percent
B-50 percent
C-75 percent
D-100 percent - ✔✔The Correct Answer Is B
NEC Section 517.73(A)(1) requires that the ampacity of supply branch-circuit
conductors and the current rating of overcurrent protective devices must not be less
than 50 percent of the momentary rating or 100 percent of the long-time rating,
whichever is greater.
✔✔The rated ampacity of conductors and overcurrent devices of a feeder for two or
more branch circuits supplying X-ray equipment for non-medical or non-dental use must
not be less than 100 percent of the momentary ratings of other X-ray apparatus?
A-5 percent
B-10 percent
C-15 percent
D-20 percent - ✔✔The Correct Answer Is D
NEC Section 660.6(B) specifies 20 percent. The minimum conductor size for branch
and feeder circuits is also governed by voltage regulation requirements. For a specific
installation the manufacturer usually specifies: minimum distribution transformer and
conductor sizes, rating of disconnect means, and overcurrent protection.
✔✔What is the maximum overcurrent device rating for each resistance welder
connected to an electrical system?
A-Not over 100 percent of the rated primary current of the welder.
B-Not over 200 percent of the rated primary current of the welder.
C-Not over 300 percent of the rated primary current of the welder.
D-Not over 400 percent of the rated primary current of the welder. - ✔✔The Correct
Answer Is C
NEC Section 630.32(A) specifies a maximum of 300 percent.
ANSWERS RATED A+
✔✔One combination that is considered by the NEC to be equivalent to an overcurrent
trip unit is _____.
A-a pole-mounted transformer and overcurrent relay
B-a submersible transformer and overcurrent relay
C-an autotransformer and overcurrent relay
D-a current transformer and overcurrent relay - ✔✔The Correct Answer Is D
NEC Section 240.20(A) states that a current transformer and overcurrent relay shall be
considered equivalent to an overcurrent trip unit.
✔✔When a fuse or circuit breaker is used for circuit protection, the fuse or overcurrent
trip unit shall be connected _____.
A-in series
B-in series and parallel
C-in parallel
D-in tandem - ✔✔The Correct Answer Is A
Fuses or overcurrent trip units (circuit breakers) must be connected in series with
ungrounded conductors so they will open or trip when an overload or ground fault
occurs. NEC Section 240.20(A). The grounding conductor is not provided with
overcurrent protection.
✔✔At what point must a branch-circuit overcurrent protection device be placed in an
electric system?
A-At the equipment ground location.
B-Where the conductor being protected receives its supply.
C-At a tap on the conductor being protected.
D-At the outlet where power is consumed. - ✔✔
✔✔The rating of the overcurrent protective device for a circuit supplying a hermetic
motor-compressor must be at least what percent of the nameplate rated-load current?
A-50 percent
B-75 percent
C-115 percent
D-150 percent - ✔✔The Correct Answer Is C
The ampere rating of the overcurrent protective device must be at least 115 percent of
the nameplate rated-load current of the compressor or branch-circuit selection current,
whichever is greater.
✔✔A multiware branch circuit protected by fuses may supply only _____.
A-half line to line loads and half line to neutral loads
B-half line to neutral loads to full or trip line to other loads
C-line to line loads
D-line to neutral loads - ✔✔The Correct Answer Is D
, NEC Section 210.4(C) requires that multiware branch circuits supply only line to neutral
loads.
✔✔What is the minimum interupting rating of an unmarked branch-circuit fuse?
A-5,000 amperes
B-10,000 amperes
C-15,000 amperes
D-20,000 amperes - ✔✔The Correct Answer Is B
NEMA and UL require fuses to be plainly marked with their characteristics including the
interrupting rating where it is other than 10,000 amperes.
✔✔When designing or installing circuits for diagnostic equipment in health care
facilities, what is the minimum percentage allowed for the momentary ampacity of the
equipment when sizing branch-circuit conductors and the overcurrent protection?
A-25 percent
B-50 percent
C-75 percent
D-100 percent - ✔✔The Correct Answer Is B
NEC Section 517.73(A)(1) requires that the ampacity of supply branch-circuit
conductors and the current rating of overcurrent protective devices must not be less
than 50 percent of the momentary rating or 100 percent of the long-time rating,
whichever is greater.
✔✔The rated ampacity of conductors and overcurrent devices of a feeder for two or
more branch circuits supplying X-ray equipment for non-medical or non-dental use must
not be less than 100 percent of the momentary ratings of other X-ray apparatus?
A-5 percent
B-10 percent
C-15 percent
D-20 percent - ✔✔The Correct Answer Is D
NEC Section 660.6(B) specifies 20 percent. The minimum conductor size for branch
and feeder circuits is also governed by voltage regulation requirements. For a specific
installation the manufacturer usually specifies: minimum distribution transformer and
conductor sizes, rating of disconnect means, and overcurrent protection.
✔✔What is the maximum overcurrent device rating for each resistance welder
connected to an electrical system?
A-Not over 100 percent of the rated primary current of the welder.
B-Not over 200 percent of the rated primary current of the welder.
C-Not over 300 percent of the rated primary current of the welder.
D-Not over 400 percent of the rated primary current of the welder. - ✔✔The Correct
Answer Is C
NEC Section 630.32(A) specifies a maximum of 300 percent.
