circuitry final

Arcing is defined as luminous discharge of electricity across an insulating medium. Electric arcs operate at temperatures between ______ and expel small particles of very hot molten material.

5,000 and 15,000 F

When a motor starts, the current drawn is at least _____ times the motor FLA; this is known as motor "locked-rotor amperes" (LRA).

6

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, but only occurs if there is a load on the circuit

False

A holding relay is primarily used for worker convenience.

False

AC inductive or capacitive reactive loads cause the voltage and current to be in-phase with each other.

False

In a dc circuit, the only opposition to current flow is the physical resistance of the material. This opposition is called reactance and is measured in ohms

False

Inverse time breakers operate on the principle that as the current decreases, the time it takes for the device to open decreases.

False

Lightning protection is intended to protect the building itself, as well as the electrical equipment on or inside the structure.

False

Magnetic lines of force can cross each other and they are called flux lines

False

The termination of the lightning stroke is unlikely to ignite combustible materials

False

To prevent fires and electric shock, the NEC specifies that neutral current can flow on metal parts of the electrical system

False

self-induced voltage opposes the change in current flowing in the conductor. This is called "inductive reactance" and it is abbreviated _____

XL

The abbreviation for impedance is ______

Z

______ can be reduced by dividing the core into many flat sections or laminations

eddy currents

For ac circuits, the ac _____ of a conductor must be taken into consideration.

eddy currents, skin effect, resistance

The total resistance of a parallel circuit can be calculated by the _____ method.

equal resistance, product-over-sum, reciprocal

The total opposition to current flow in ac circuits is called ______ and measured in ohms

impedance

Transformers are rated in

kVA

Factors that affect the available short-circuit current include circuit conductor _______

material, size, length

Ohmmeters measure the _____ or opposition to current flow of a circuit or component.

resistance

The Megger is used to measure very high-_____ values, such as those found in cable insulation, or motor and transformer windings.

resistance

The _____ of a generator is forced to rotate while it is being subjected to the magnetic field of the stator

rotor

The ______ of an ac generator contains the electromagnetic field, which cuts through the stationary conductor coils

rotor

The effective value is equal to the peak value ______.

times 0.707

Swapping _____ of the line conductors can reverse a three-phase ac motor's rotation

two

A GFCI is designed to protect persons against electric shock. It operates on the principle of monitoring the imbalance of current between the circuit's _______ conductor

ungrounded and neutral

_______ motors are fractional horsepower motors that operate equally well on ac and dc and are used for vacuum cleaners, electric drills, mixers, and light-household appliances

universal

Factors that affect the available short-circuit current include transformer ______

voltage, kVA rating, impedance

The induced voltage in a conductor carrying alternating current opposes the change in current flowing through the conductor. The induced voltage that opposes the current flow is called ______

CEMF, counter-electromotive force, back-EMF

Non magnetic metals are ferrous, meaning they don't contain any iron and cannot be magnetized

False

The best conductors, in the order of conductivity, are gold, silver, copper, and aluminum.

False

The motor FLA rating is used when sizing motor conductors or circuit protection.

False

Because of conductor resistance, flux leakage, eddy currents, and hysteresis losses, not all of the input power is transferred to the secondary winding for useful purposes.

True

Circuit breakers and fuses are intended to interrupt the circuit, and they must have an ampere interrupting rating (AIR) sufficient for the available short-circuit current.

True

Electrons leaving a power supply are always trying to return to the same power supply; they are not trying to go into the earth.

True

Even when power is removed from the circuit, capacitors can store large amounts of energy for a long period of time. They can discharge and arc if inadvertently shorted or grounded out.

True

If a conductor is carrying current next to another conductor carrying current in the opposite direction, the electro-magnetic field attempts to push the conductors apart

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

If the ungrounded conductors of a multiwire circuit are not terminated to different phases, this can cause the neutral current to exceed the grounded conductor rating.

True

In an ac induction motor, the stator produces a rotating magnetic field that induces current in the rotor windings. The rotor current generates a magnetic field in opposition to the magnetic field of the stator, thereby causing the rotor to turn.

True

Kirchoff's Voltage Law states, "In a series circuit, the sum of the voltage drops across all of the resistors will equal the applied voltage."

True

Lightning frequently terminates to an elevated point and it strikes nonmetallic as well as metallic objects with the same frequency.

True

Metal parts of premises wiring must be bonded to a low-impedance path designed so that the circuit protection device will quickly open and clear a ground fault

True

People become injured and killed when voltage pushes electrons through the human body causing the heart to go into ventricular fibrillation

True

Unsafe arcing faults can occur in one of two ways, as series arcing faults or as parallel arcing faults. The most dangerous is the parallel arcing fault

True

Voltage induced in the secondary winding of a transformer is dependent on the number of secondary turns as compared to the number of primary turns.

True

When power supplies are connected in parallel, the voltage remains the same, but the current or amp-hour capacity will be increased.

True

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.

True

The opposition offered to the flow of ac current by a capacitor is called "capacitive reactance", which is expressed in ohms and abbreviated _______.

Xc

Wasteful circulating _____ in the iron core cause(s) the core to heat up without any useful purpose.

eddy currents

Because of the earth's _____ resistance to current flow, it cannot be used for the purpose of clearing a line-to-case fault

high

As current flows through the transformer, the iron core is temporarily magnetized. The energy required to realign the core molecules to the changing electromagnetic field is called "____" loss.

hysteresis

A clamp-on ac ammeter has a coil that is clamped around the conductor and detects the rising and falling _____ field being produced due to the ac flow through the conductor.

magnetic

The electric motor works on the principle of the attracting and repelling forces of _____ fields.

magnetic

A nonsinusoidal waveform is created when _____ loads distort the voltage and current sine wave

nonlinear

The purpose of overcurrent protection is to protect conductors and equipment against excessive or dangerous temperatures because of overcurrent. Overcurrent is current in excess of the rated current of equipment or conductors. It may result from a(n) _____.

overload, short circuit, ground fault

To protect against electric shock or to prevent a fire, a dangerous ______ must quickly be removed by opening the circuit's overcurrent protection device.

overload, short circuit, ground fault

Improper wiring or mishandling of multiwire circuits can cause _____ connected to the circuit.

overloading of the neutral conductors, destruction of equipment because of voltage (b and c)

Dual-voltage ac motors are made with two field windings. The field windings are connected in _____ for low-voltage operation and in _____ for high-voltage operation.

parallel, series

Magnetic time-delay circuit breakers operate on the solenoid principle where a movable core, held with a spring, is moved by the magnetic field of a(n) _____.

short circuit or ground fault (b or c)

The expanding and collapsing magnetic field within the conductor induces a voltage in the conductors (CEMF) that repels the flowing electrons toward the surface of the conductor. This is called "_____."

skin effect

In a ____ motor, the rotor is locked in step with the rotating stator field and is dragged along at the speed of the rotating magnetic field

synchronous

Kirchoff's Current Law states, "In a series circuit, the current is _____ through the transformer, the conductors, and the appliance.

the same

The ______ sensing element causes the circuit breaker to open when a predetermined calibration temperature is reached

thermo

An electrical arc blast can approach _______

30,000 F

Three-phase, _____ wye-connected systems can overheat because of circulating odd triplen harmonic currents.

4-wire

Three-phase ac generators have three equally spaced windings, _____ out-of-phase with each other.

120 degrees

Providing a path to the earth often helps reduce electrostatic charge.

True

Severe electric shock or death can occur if a person touches the ungrounded and the neutral conductors at the same time, even if the circuit is GFCI protected.

True

The current flowing on the neutral conductor of a multi-wire circuit is called "unbalanced current".

True

The energy transfer ability of a transformer is accomplished because the primary electromagnetic lines of force induce a voltage in the secondary winding

True

The heating from harmonic currents is proportional to the square of the harmonic current.

True

The major advantage of ac over dc is the ease of voltage regulation by the use of a transformer

True

The opposition to current flow results in voltage drop.

True

The severity of an electric shock is dependent on the current flowing through the body, which is impacted by circuit voltage and contact resistance.

True

Typically, when a GFCI-protection device fails, the switching contacts remain closed and the device will continue to provide power without GFCI protection.

True

If the primary phase voltage is 480V and the secondary phase voltage is 240V, the turns ratio is _____.

2:1

A balanced 3-wire, 120/240V, single-phase circuit is connected so that the ungrounded conductors are from different transformer phases (Line 1 and Line 2). The current on the neutral conductor will be ______ percent of the ungrounded conductor current.

0

According to Kirchoff's Current Law, the total current provided by the source to a parallel circuit will equal the sum of the currents of all the branches.

True

According to the Electron current flow theory, electrons flow away from the negative terminal of the source, through the circuit and load, toward the positive terminal of the source

True

According to the conventional current flow theory, electrons travel from positive to negative

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 the current in amperes that is available at a given point in the electrical system.

True

Because of the dangers associated with the open neutral (grounded conductor), NEC 300.13(B) does not permit the continuity of the ____ conductor to depend on a receptacle.

neutral

When describing the relationship between voltage and current, the reference waveform is always ______

voltage