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Fuses and circuit breakers are intended to protect conductors and equipment from the effects of
potentially harmful _____.
a. overcurrents
b. overvoltages
c. both a. and b. - (ANSWER)a. overcurrents
T/F
Overload current is confined to the normal conductive path provided by the conductors, circuit devices,
and loads of the distribution system. - (ANSWER)True
Short-circuit current _____ the normal conducting path.
a. flows in the reverse direction as overload current in
b. flows outside
c. is entirely confined to - (ANSWER)b. flows outside
Because of the ____ impedance path, a 3-phase bolted fault condition is typically assumed to be the
highest level of fault current.
a. high
b. low
c. reactive
d. resistive - (ANSWER)b. low
Which of the following statements is not correct per Article 100 definition?
a. Branch-circuit overcurrent protective devices are capable of being able to provide a full range of
overcurrent protection from rated current to its interrupting rating.
b. Branch-circuit overcurrent protective devices are intended for protection of a service, feeder or
branch circuit of an electrical system.
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c. Branch-circuit overcurrent protective devices must be listed in combination with the specific device it
is intended to protect.
d. Branch-circuit overcurrent protective devices must have interrupting rating sufficient for the
application, but not less than 5 kA. - (ANSWER)c. Branch-circuit overcurrent protective devices must be
listed in combination with the specific device it is intended to protect.
T/F
Supplementary overcurrent protective devices are permitted to be used as a substitute for a branch-
circuit OCPD or where a branch-circuit OCPD is required (240.10). - (ANSWER)False
A ___ protective device is one that clears a fault current in one-half cycle or less and reduces the amount
of short-circuit current let-through.
a. branch circuit
b. current-limiting
c. motor circuit
d. surge - (ANSWER)b. current-limiting
T/F
When fault current is within the current-limiting range of a current-limiting OCPD, the thermal energy
and magnetic (mechanical) forces can be greatly reduced. The levels of both thermal energy and
magnetic forces are proportional to the square of the fault current that flows - (ANSWER)True
How can a 600-volt or less branch-circuit OCPD be identified as being current limiting?
a. Ask the manufacturer.
b. Read the data sheet.
c. The circuit breaker or fuse will be marked "current-limiting".
d. There are no 600-volt current-limiting branch circuit OCPDs - (ANSWER)c. The circuit breaker or fuse
will be marked "current-limiting".
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T/F
The voltage rating of the OCPD must be equal to but never greater than the circuit voltage. -
(ANSWER)False
T/F
A 600-volt AC fuse or circuit breaker is considered to have a 600-volt DC rating, even if it is not marked
with a DC voltage rating. - (ANSWER)False
What NEC section limits the use of slash voltage rated circuit breakers for solidly grounded wye systems
only where the line-to-ground voltage does not exceed the lower of the two values and the line-to-line
voltage does not exceed the higher value?
a. 240.4
b. 240.67
c. 240.85
d. There is no such NEC requirement. - (ANSWER)c. 240.85
T/F
Branch circuit fuses do not have to be marked with their ampere rating. - (ANSWER)False
T/F
Per Article 240, the standard ampere ratings of fuses and circuit breakers must be used in an electrical
distribution center. - (ANSWER)False
T/F
When the conductor ampacity does not correspond to a standard OCPD ampere rating, the next
standard OCPD ampere rating is permitted if that rating does not exceed 800 amperes, and if the
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conductors are not supplying a circuit with more than one receptacle for cord-and-plug portable loads -
(ANSWER)True
T/F
For motor branch circuit applications, the motor branch circuit short-circuit and ground fault protective
device can be located anywhere on the motor branch circuit since short-circuit currents stay within the
normal conducting path. - (ANSWER)False
Molded case circuit breakers, insulated case circuit breakers, and low voltage power circuit breakers are
____ .
a. application-limited OCPDs which are suitable for specific branch circuit applications, under limited
conditions per the NEC
b. branch circuit overcurrent protective devices
c. supplementary OCPDs - (ANSWER)b. branch circuit overcurrent protective devices
MCPs are recognized devices (not listed) and are permitted by _____ to provide motor branch-circuit
short-circuit and ground-fault protection, if used as part of a listed combination with a starter.
a. 430.32
b. 430.52(C)(1)
c. 430.52(C)(3)
d. 430.53 - (ANSWER)c. 430.52(C)(3)
Which statement about supplementary protectors is not correct?
a. Cannot be used in place of branch-circuit protection
b. Intended where branch-circuit protection not required
c. Recognized to UL 1077
d. Suitable for branch-circuit protection - (ANSWER)d. Suitable for branch-circuit protection
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Fuses and circuit breakers are intended to protect conductors and equipment from the effects of
potentially harmful _____.
a. overcurrents
b. overvoltages
c. both a. and b. - (ANSWER)a. overcurrents
T/F
Overload current is confined to the normal conductive path provided by the conductors, circuit devices,
and loads of the distribution system. - (ANSWER)True
Short-circuit current _____ the normal conducting path.
a. flows in the reverse direction as overload current in
b. flows outside
c. is entirely confined to - (ANSWER)b. flows outside
Because of the ____ impedance path, a 3-phase bolted fault condition is typically assumed to be the
highest level of fault current.
a. high
b. low
c. reactive
d. resistive - (ANSWER)b. low
Which of the following statements is not correct per Article 100 definition?
a. Branch-circuit overcurrent protective devices are capable of being able to provide a full range of
overcurrent protection from rated current to its interrupting rating.
b. Branch-circuit overcurrent protective devices are intended for protection of a service, feeder or
branch circuit of an electrical system.
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c. Branch-circuit overcurrent protective devices must be listed in combination with the specific device it
is intended to protect.
d. Branch-circuit overcurrent protective devices must have interrupting rating sufficient for the
application, but not less than 5 kA. - (ANSWER)c. Branch-circuit overcurrent protective devices must be
listed in combination with the specific device it is intended to protect.
T/F
Supplementary overcurrent protective devices are permitted to be used as a substitute for a branch-
circuit OCPD or where a branch-circuit OCPD is required (240.10). - (ANSWER)False
A ___ protective device is one that clears a fault current in one-half cycle or less and reduces the amount
of short-circuit current let-through.
a. branch circuit
b. current-limiting
c. motor circuit
d. surge - (ANSWER)b. current-limiting
T/F
When fault current is within the current-limiting range of a current-limiting OCPD, the thermal energy
and magnetic (mechanical) forces can be greatly reduced. The levels of both thermal energy and
magnetic forces are proportional to the square of the fault current that flows - (ANSWER)True
How can a 600-volt or less branch-circuit OCPD be identified as being current limiting?
a. Ask the manufacturer.
b. Read the data sheet.
c. The circuit breaker or fuse will be marked "current-limiting".
d. There are no 600-volt current-limiting branch circuit OCPDs - (ANSWER)c. The circuit breaker or fuse
will be marked "current-limiting".
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T/F
The voltage rating of the OCPD must be equal to but never greater than the circuit voltage. -
(ANSWER)False
T/F
A 600-volt AC fuse or circuit breaker is considered to have a 600-volt DC rating, even if it is not marked
with a DC voltage rating. - (ANSWER)False
What NEC section limits the use of slash voltage rated circuit breakers for solidly grounded wye systems
only where the line-to-ground voltage does not exceed the lower of the two values and the line-to-line
voltage does not exceed the higher value?
a. 240.4
b. 240.67
c. 240.85
d. There is no such NEC requirement. - (ANSWER)c. 240.85
T/F
Branch circuit fuses do not have to be marked with their ampere rating. - (ANSWER)False
T/F
Per Article 240, the standard ampere ratings of fuses and circuit breakers must be used in an electrical
distribution center. - (ANSWER)False
T/F
When the conductor ampacity does not correspond to a standard OCPD ampere rating, the next
standard OCPD ampere rating is permitted if that rating does not exceed 800 amperes, and if the
, RICARDOS 4TH TEST |COMPLETE STUDY GUIDE WITH 100%
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conductors are not supplying a circuit with more than one receptacle for cord-and-plug portable loads -
(ANSWER)True
T/F
For motor branch circuit applications, the motor branch circuit short-circuit and ground fault protective
device can be located anywhere on the motor branch circuit since short-circuit currents stay within the
normal conducting path. - (ANSWER)False
Molded case circuit breakers, insulated case circuit breakers, and low voltage power circuit breakers are
____ .
a. application-limited OCPDs which are suitable for specific branch circuit applications, under limited
conditions per the NEC
b. branch circuit overcurrent protective devices
c. supplementary OCPDs - (ANSWER)b. branch circuit overcurrent protective devices
MCPs are recognized devices (not listed) and are permitted by _____ to provide motor branch-circuit
short-circuit and ground-fault protection, if used as part of a listed combination with a starter.
a. 430.32
b. 430.52(C)(1)
c. 430.52(C)(3)
d. 430.53 - (ANSWER)c. 430.52(C)(3)
Which statement about supplementary protectors is not correct?
a. Cannot be used in place of branch-circuit protection
b. Intended where branch-circuit protection not required
c. Recognized to UL 1077
d. Suitable for branch-circuit protection - (ANSWER)d. Suitable for branch-circuit protection
