Mike Holt 1 Flashcards
Providing a path to the earth often helps reduce electrostatic charge
True
Lighting frequently terminates to a point of elevation and it strikes nonmetallic as well as metallic object with the same frequency
True
The termination of the lighting strike is unlikely to ignite combustible materials
False
Lighting protection is intended to protect the building structure itself, as well as the electrical equipment on or inside the building structure
False
Nonmagnetic metals are ferrous, meaning they do not contain any iron, and cannot be magnetized
False
Magnetic lines of force can cross each other and they are called flux lines
False
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
People become injured and death may occur with voltage pushes electrons through the human body causing the heart to go into ventricular fibrillation
True
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
An electrical arc blast can approach ______ Which can vaporize metal parts and produce an explosive deadly pressure wave
30,000f
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
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
Ohmmeters measure the \_\_\_\_\_ or opposition to current flow of a circuit or component A. Voltage B. Current C. Power D. Resistance
D. Resistance
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
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
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
A holding relay is primarily used for workers convenience
False
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, electric current travels from positive to negative
True
One major advantage of ac over dc is the ease of voltage regulation by the use of a transformer
True
The best conductors, in order of their conductivity, Are gold, silver, copper, And aluminum
False
Silver, Copper, Gold, Aluminum
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
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
The opposition to current flow results in voltage drop
True
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
2
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
4’
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
5’
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
5’
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
1’
Portable distribution equipment for carnivals must be located at lease _______ above the ground
6”
The minimum clearance between an electric space-heating cable and an outlet box used for surface luminaries shall not be less then ______
8”
PV wires must be grouped at intervals of _______
6’
Ground wire shall not have to be larger then ______
6
Cables installed in agriculture buildings shall be secured within ________ of each cabinet, box or fitting
8”
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
4
A run of RMC shall not contain more than the equivalent of _______ quarter bends between pull points such as conduit bodies and fittings
4
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
C=
Capacitance
L=
Inductor
R = Resistance
ohms
P = Power
Watts
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
