15
Arcing is a luminous discharge of electricity across an insulating medium. Electric arcs operate at temperatures between
5,000 and 15,000 F
If the difference between the current leaving and returning through the current transformer of the GFCI protection device exceeds ______, the solid state circuitry de-energizes the circuit
5mA
To help reduce the hazard of t electrical fires from a parallel fault, the NEC requires a listed AFCI protection device to protect _______ wiring in dwelling unit bedrooms
Branch circuit
When equipment does not have a withstand rating sufficient for the available fault current, the equipment can be protected by the use of _________
Current listing fuses
A GFCI protection device contains an internal monitor that prevents the device from being turned on if there is a neutral to case connection downstream of the device.
False
Ground fault protection devices protect equipment from Samsung ground fault currents by opening all ungrounded conductors of the faulted circuit. This device also protects People
False
Inverse time breakers operate on the principle that as the current decreases, the time it takes for the device to open decrease
False
A ground fault type parallel arc only occurs when a ground a path is present. This type of acting fault can be quickly cleared by a
GFCI & AFCI
To remove dangerous touch voltage on metal parts from a ________, the fault-current path must have low impedance to allow the fault current to quickly rise to facilitate the opening of the protection device
Ground fault
________ breakers operate on the principle of electromagnetism only and are used for very large motors
Instantaneous trip
__________ breakers operate on the principle that as the current increases, the time it takes for the device to open decreases
Inverse time
A fuse consists of an element electrically connected to end blades, which is enclosed in a tube and surrounded by a _______ filler material
Nonconductive
An _____ is the operation of equipment or conductors in excess of Their rated ampacity
Overload
As current flows through the element of a fuse, it generates heat. When sustained overload occurs, the heat melts _______, stopping the flow
Portion of the element
When a short circuit or forums fault occurs, _______ melt removing the load from the source very quickly
Several elements
Equipment must have a ________ current rating that permits the protection device to clear a short circuit or ground fault without extensive damage to the components of the circuit
Short circuit
The current in a short circuit type arc is limited by the system impedance and the impedance of the arcing fair. Typical fault current will be above 75A but no above
450A
Magnetic time-delay circuit breakers operate on the on the solenoid principle where a movable core, held with a spring is moved by the magnetic field a ________
B or C
Severe electric shock or death can occur if a person touches the undergrounded and the neutral conductors at the same time, even if the circuit is GFCI protected
True
The opening time for a protection device is inversely proportional to the magnitude of the current. The greater the current value, the less time it takes for the protection device to open
True
Typically when a GFCI protection device fails the switching contacts Ramon closed and the device will continue to provide power without GFCI protection
True
Unless marked otherwise, circuit breakers have a 5,000 AIC rating and fuses have a 10,000 AIC rating
True
Unsafe arcing faults can occur in one of two ways, as series acting faults or as parallel acting faults. The most dangerous is the parallel arcing fault
True
A GFCI is designed to protect persons against electric shock. It operates on the principle of monitoring the imbalance of the circuits _______ conductors
Ungrounded and grounded
The available short circuit is different at each point of the electrical system; it is the highest at the __________
Utility transformer
According to NEMA report, 11% of the GFCI breakers protecting indoor receptacles failed, and ________ percent protecting outdoor receptacles failed
20
A short circuit is a ________ electrical connection between any two conductors of the electrical system
A or B
_________breakers permit the thermal trip setting to be adjusted to coordinate the circuit breaker's operation with other protection devices
Adjustable trip
Factors that impact the available short circuit current include circuit conductor ___________
All of these
Factors that impact the available short-circuit current include transformer ____________
All of these
The purpose of overcurrent protection is to protect conductors and equipment against excessive or dangerous temperatures because of over current. Overcurrent is is current in excess of the rated current of equipment or conductors. May result in _______
All of these
To protect against electric shock or to prevent a fire, a dangerous ________ must quickly be removed by opening the circuits overcurrent device
All of these
A thermal magnetic circuit breaker typically clears fault current in less that 3 to 5 cycles when subjected to a
B or C
The ________ sensing element causes the circuit breaker to open when a predetermined calibration temperature is reached
Thermal
A series arc can occur when the conductor in series with the load is unintentionally broken. A series arc fault current is load limited
True
An AFCI protection device provides protection from an arcing fault by recognizing the characteristics unique to a parallel arcing fault and by functioning to de energize the circuit when an arc fault is detected
True
Available short circuit current is current in amperes that is available at a given point in the electrical system
True
Circuit breakers and fuses are intended to interrupt the circuit and they must have an ampere interrupting eating sufficient for the available short circuit current
True
If the protection device is not rated to interrupt the available fault current at its listed voltage rating, it can explode while attempting to clear the fault
True
