Purpose of Overcurrent Protection
A(n) ______ is best defined as any current in excess of the rated current.
Overcurrent
What is not a rating used when selecting overcurrent protective devices.
Frame size
How can it be determined if a circuit breaker is current-limiting?
It will be marked "Current-Limiting".
A fuse uses a conductive _____ link or links encapsulated in a tube with compacted silica sand and connected to contact terminals.
Fusible
_____ is a system intended to provide protection of equipment from damaging line-to-ground fault currents by operating to cause a disconnecting means to open all ungrounded conductors of the faulted circuit.
Ground-fault protection of equipment
A(n) _____ is a current greater than the equipment rated current or conductor ampacity, which is confined to the normal conductive paths.
Overload
True or False. Fuses have straight and slash voltage ratings.
False
Interrupting ratings on AC rated circuit breakers are used for _____.
AC systems only
The electrical resistance of the fuse link is so low, it simply acts as a(n) _____ during the normal circuit operation.
Residual ground-fault protection monitors ground fault currents in the _____.
Grounding Strap
What electrical circuit best describes a phase or ungrounded conductor that comes into contact with another phase conductor or grounded conductor object?
Short circuit
The highest current at rated voltage that a device is identified to interrupt under standard test conditions describes _____.
Interrupting rating
The operating characteristics of an OCPD trip curve can be visually displayed in a _____ curve.
Time-current
Nontime-delay fuses use a(n) _____ element fuse construction.
Single
Ground-fault protection of equipment is not permitted for _____ or required for a continuous industrial process where a non-orderly shutdown would introduce additional or increased hazards.
Fire pump circuits
When analyzing a short-circuit current, if the fault current level is equal above and below the zero axis of a sine wave, the fault current is _____.
Symmetrical
If a branch-circuit fuse is not marked with an interrupting rating, then the interrupting rating for that fuse is ______.
10,000 amps
What devices are permitted to be used as branch circuit OCPDs in service, feeders, and branch circuits?
Molded Case Circuit Breakers
Generally, the overload element of a branch-circuit dual-element time-delay fuse will hold an overload that is five times greater than the ampere rating of the fuse for a minimum time of ______.
10 seconds
The ______ of ground-fault protection can depend upon the components, wiring, setting, and maintenance of not just the relay, but also the proper installation of the building wiring system.
Reliability
What is recognized as the safest work practice for working on a circuit?
Typically what is the single most influencing factor on the magnitude of the available short-circuit current at the service?
Which type of circuit breaker is designed to be reconditioned?
Low-voltage power circuit breakers
Listed current-limiting fuses have ______ features that help prevent the installation of fuses that cannot provide a comparable minimum protection level of critical ratings and performance.
Rejection
The ground-fault protection system must operate to cause the service disconnect to open all ungrounded conductors of the faulted circuit. The maximum setting of the ground-fault protection permitted is _____, and the maximum time-delay setting is _______ for ground-fault currents equal to or greater than 3,000 amperes.
1,200 A / 1 second