CHAPTER 2 , CONDUCTORS

Question 1

• any material that conducts electrical current.

• A wire is a common electrical ___________.

Answer 1

conductorS

Question 2

• consist of smaller wire strands.

• The basic reason for using a stranded conductor is to make the conductor __________

Answer 2

stranded conductorS, flexible

Question 3

• constructed of one single piece of metal.

• tougher than a stranded conductor but rigid and less flexible.

• more likely to break if subjected to frequent flexing than stranded conductors.

Answer 3

solid conductors

Question 4

• the best electrical conductor material (other than a superconductor material)

Answer 4

silver

Question 5

used in BUILDING CONDUCTOR (wiring) INSTALLATIONS as a compromise between GOOD CONDUCTIVITY AND ECONOMY. • The wire core is aluminum with a thin coating of _______ that is metallurgically bonded to the core

Answer 5

copper

Question 6

• has significant WEIGHT AND COST ADVANTAGES over copper. Copper does, however, conduct electricity better than aluminum, so an aluminum wiring installation requires a thicker ________.

• Also, extra care in splicing and terminating aluminum wire is important.

Answer 6

aluminum, gauge

Question 7

• covered with insulation that provides electrical isolation and some physical protection of the conductor material.

• prevents loss of power and the danger of short circuits and ground faults.

Answer 7

CONDUCTOR INSULATION

Question 8

• contains more than one CONDUCTOR BUNDLED together in a factory assembly of wires.

• An outer sheathing encases and protects the conductors, simplifying the installation of multiple wiring.

Answer 8

CABLE

Question 9

• a wiring system composed of VERY THIN CABLE with three or more conductors and special connectors and terminals.

• designed to rest between the topside of a smooth continuous subfloor and carpet squares.

Answer 9

FLAT CONDUCTOR CABLE

Question 10

• used in applications with voltages LESS THAN 30 V, such as wiring to doorbells, chimes, and thermostats.

• generally contains No. 16 AWG or No. 18 AWG conductors that are bundled in a thin plastic sheathing.

Answer 10

THERMOSTAT CABLE

Question 11

• made of stranded conductors within a flexible insulated sheathing material.

• They are designed for flexibility and bending.

Answer 11

CORD

Question 12

A wiring method uses knobs, tubes, and flexible nonmetallic tubing to protect and support single Insulated conductors.

Answer 12

concealed knob-and-tube wiring

Question 13

• Heat generated by current flow through the conductor results in a loss of power.

• This lost power is referred to as __________ or line loss..

Answer 13

conductor power loss

Question 14

• Power loss is converted directly to ________. Power loss is equivalent to the ______ produced. The relationship between power and _______ is 1 W _______ Btu/hr. The following formula can compute the heat created (q) for a known power loss (Ploss):

Answer 14

heat, heat, heat, 3.413

Question 15

• the MAXIMUM that a conductor can carry continuously under the conditions of use without exceeding its TEMPERATURE RATINg.

• Current is MEASURED in amperes or “_______.” You must use the correct size wire for the current (load) requirement of the circuit to prevent the wire from overheating.

Answer 15

conductor ampacity, amps

Question 16

ampacity is based on the following:

Answer 16

wire thickness
type of conductor material
insulation and sheathing type
number of conductors bundled
temperature

Question 17

• Because of power losses, voltage is reduced in a closed circuit — that is, the voltage across two conductors is lower at the usage end than at the power supply end of the circuit.

• _________ is directly proportional to power loss

Answer 17

Voltage drop