Mike Holt 1 Flashcards by jay irons

Providing a path to the earth often helps reduce electrostatic charge

True

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Lighting frequently terminates to a point of elevation and it strikes nonmetallic as well as metallic object with the same frequency

True

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The termination of the lighting strike is unlikely to ignite combustible materials

False

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

False

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Nonmagnetic metals are ferrous, meaning they do not contain any iron, and cannot be magnetized

False

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

False

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It is not the force of magnetic field through a conductor that produced electricity it is the relative motion of the field the the electrons within the conductor that produces the movement electrons

True

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People become injured and death may occur with voltage pushes electrons through the human body causing the heart to go into ventricular fibrillation

True

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

True

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An electrical arc blast can approach ______ Which can vaporize metal parts and produce an explosive deadly pressure wave

30,000f

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IF a conductor carrying current is next to another conductor carrying current in the opposite direction, The electromagnetic field attempts to push the conductors apart

True

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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
A. static
B. Current
C. Power
D. Magnetic

D. Magnetic

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Ohmmeters measure the \_\_\_\_\_ or opposition to current flow of a circuit or component 
A. Voltage 
B. Current
C. Power
D. Resistance

D. Resistance

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The megger is used to measure very high \_\_\_\_\_\_ values such as those found in cable insulation, or motor and transformer windings 
A. Voltage
B. Current 
C. Power
D. Resistance

D. Resistance

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The electric motor works on the principle of the attracting and repelling forces of the \_\_\_\_\_ Fields
A. Voltage
B. Current
C. Power
D. Magnetic

D. Magnetic

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The\_\_\_\_\_\_\_ of a generator is forced to rotate while it is being subjected to the magnetic field of the stator 
A. Winding 
B. Rotor
C. Stator 
D. B or C

B. Rotor

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A holding relay is primarily used for workers convenience

False

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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

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According to the conventional current flow theory, electric current travels from positive to negative

True

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

True

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The best conductors, in order of their conductivity, Are gold, silver, copper, And aluminum

False

Silver, Copper, Gold, Aluminum

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

False

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The formulas in the power wheel apply to 
A. DC
B. AC with unity power factor 
C. DC or AC circuits 
D. A & B

D. A & B

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The opposition to current flow results in voltage drop

True

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Kerchief's Voltage Law state that in a series circuit the sum of the voltage drops across all of the resistors will equal the applied voltage

True

``` Kerchief's current law states that in a series circuit the current is ______ throughout the transformer the conductors and the appliance A. Proportional B. Distributed C. Additive D. The same ```

D. The Same

Kerchief's current law the total current provided by the source to a parallel circuit will equal the sum of the current of all of the branches

True

Because of the dangers associated with an open grounded conductor the continuity of the grounded conductor of a multi-wire branch circuit cannot be dependent upon the receptacle

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

``` The total opposition to current flow in ac circuits is called _______ and is measured in ohms A. resistance B. reactance C. impedance D. Skin effect ```

C. impedance

If the primary phase voltage is 480v and the secondary phase voltage is 240v the turns ration is _______

2 to 1

In a hotel _______ receptacles shall be readily accessible

The supply side bonding jumper on the supply side of services shall be sized according to the ________

Ungrounded supply conductor size

``` Motors shall be located so that adequate _____ is provided and so that maintenance such as lubrication of bearings and replacing of brushes can be readily accessible A. Space B. ventilation C. Protection D. All of these ```

B. Ventalation

``` The allowable ampacity of flexible cords and cables is found in _________ A. Table 310.15 B. Table 400.5(A)(1) C. Chapter 9 Table 1 D. Table 430.52 ```

B. Table 400.5(A)(1)

Except by special permission no conductor larger then _____ AWG shall be installed in a cellular metal floor raceway

1/0

The minimum clearance for overhead conductors not exceeding 600v that pass over commercial areas subject to truck traffic is

18'

At least 1 receptacle shall be installed within 18" of the top of a show window for each ______ section

12'

The maximum voltage permitted between ungrounded conductors of flat conductors cable systems is _____

300v

The length of a cord for a dishwashers, trash compactor shall not be more than ______ measured from the back of the appliance

Where flexible cords are used in ambient temperature other then _______ the temperature correction factors from table 310.15 shall be applied to the ampacity from table 400.5

30deg C

Metal raceways and metal piping within _____ of a hot tub must be bonded

A wall mounted laminar weighing not more that _____ can be supported by a 6/32 screws

6 ib

``` Which of the following is not standard size fuse or inverse time circuit breaker A. 45A B. 70A C. 75A D. 80A ```

C.75A

Underground PVC pipe shall not be closer than ______ unless space limitations prevent otherwise

For a stationary motor 2hp or less and 300v or less Ac current, the controller can be ac-rated only general-use snap switch where the motor full-load current rating is not more than ________ percent of the rating of the switch

80%

Mobile home services cannot be less then

100a

Liquidtight flexible metal conduit must be secured within ____ of the termination

Portable distribution equipment for carnivals must be located at lease _______ above the ground

The minimum clearance between an electric space-heating cable and an outlet box used for surface luminaries shall not be less then ______

PV wires must be grouped at intervals of _______

Ground wire shall not have to be larger then ______

Cables installed in agriculture buildings shall be secured within ________ of each cabinet, box or fitting

Isolated ground receptacles are identified with _____

Orange Triangle

This must be used to provide shore power

Circuit breaker or switch both clearly marked

An optical fiber cable is a factory assembly of one or more optical fibers having __________ covering that transforms light for control, signaling and communications

overall

When an elevator room has more then 1 elevator drive they shall be number and ____________

identifying the number of drive machinery they control

A _________ location may be temporarily subject to dampness and wetness

Dry

Factory installed internal wiring of listed equipment need not be inspected as the time of installation of equipment ,except to detect alterations or damage

True

Type mc cable can be unsupported where not more then 2' of length at terminals where flexibility is necessary T or F

True

Compliance with the provisions of the NEC will result in

An electrical system essentially free from hazard

``` Surface non-matalic raceways shall be permitted A. in dry locations B. where concealed C. in hoistways D. all of these ```

A. in dry locations

A panel board shall be protected by an overcorrect devise within the panel board or at any point on the ______ side of the panel board

Supply side

``` All switchboards, panel boards and motor control centers shall be A. located in dedicated spaces B. protected from damage C. in weatherproof enclosures D. A and B ```

D. A and B

A devise comprised of ________ or more receptacles shall be calculated at not less then 90 VA per receptacle

A run of RMC shall not contain more than the equivalent of _______ quarter bends between pull points such as conduit bodies and fittings

The branch-circuit, short-circuit protection devise for a 10hp 230v single phase motor shall not exceed _______ Motors can not be sized more than 250% of the motors FLA

125a

The voltage will lead the current when the inductive reactance exceeds the capacitive reactance

True

The current will lead the voltage when capacitive reactance exceeds the inductive reactance in the circuit

True

I = Intensity

Current Amps

E & Energy V Are (emf)

Voltage

Capacitance

Inductor

R = Resistance

ohms

P = Power

Watts

= Power

Ohms (resistance)

Power Consumed

Wasteful circulating ___________in the iron core causes the core to heat up without and useful purpose

eddy currents

The Energy transfer ability of a transformer is accomplished because the primary electromagnetic lines of force induced a voltage in the secondary windings T or F

True

____________ Can be reduced by dividing the core into many flat sections or laminations

Eddy Currents

The heat from harmonic currents is proposed to the square of the harmonic order

True

The current flow through the transformer, the iron core is temporarily magnetize. The energy required to realign the core molecules to the changing electromagnetic field is called _________ loss

Hysteresis

Because of conductor resistance, flux leakage eddy currents and hysteresis losses not all of the input power is transferred to the secondary windings for useful purpose T or F

True

In DC circuits, the only opposition to current flow is the physical resistance of the material. This opposition is called reactance and it is measured in ohms

False

``` The formulas in the power wheel apply to ______ A. DC B. AC With unity power factor C. DC & AC circuits D. A & B ```

DC and AC with unity power factor

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 beaches

True

``` Because of the earth's high resistance to current flow, it cannot be used for the purpose of clearing a line to case ground fault for _________ wiring A. Utility B. Premises C. A or B D. None of these ```

Premises

``` Equipment must have a _______current rating that permits the protection devise to clear a short circuit or ground fault without extensive damage to the components of the circuit A. Overload B. Short Circuit C. Ground Fault D. B or C ```

Short circuit

``` Arcing is defined as a luminous discharge of electricity across an insulated medium. Electric arcs operates at temperatures between _______and expel small particles of very hot molten materials A. 1,000 and 5,000F B. 2,000 and 10,000F C. 5,000 and 15,000F D. 10,000 and 25,000 ```

C 5,000 and 15,000

``` The expanding and collapsing magnetic field within the conductors induces a voltage in the conductors )CEMF) that repels the flowing electrons toward the surface of the conductor. This is called _______ A. eddy currents B. induced voltage C. impedance D. Skin Effect ```

Skin effect

``` Total opposition to current flow in ac circuit is called _____ and is measured in ohms A. Resistance B. reactance C. impedance D. Skin Effect ```

C impedance

Mike Holt 1 Flashcards

(91 cards)