conductor sizes & wire tables

4 factors determine the resistance of a length of wire are.

1. The type material from which the wire is made. 2. The diameter of the conductor. 3. The length of the conductor 4.the temperature of the conductor

The American Wire Gauge (AWG)

Is used for diameters of round,solid, and nonferrous electrical wire.

Megger

Used to measure high resistances

One of the main factors that determines the amount of current a conductor is permitted to carry is the _______.

ambient(surrounding,air temp)

duct banks

are often used when it becomes necessary to bury cables in the ground.

NEC 310 deals with_______

conductors for general wiring.

Ampacities is _______

current~carrying ability.

The gauge size is important for determining the______of a conductor.

current~carrying capacity

If a raceway is to contain more than three conductors, the ampacity of the conductor must be

derated because the heat from each conductors combine with the heat dissipated by the other conductors to produce a higher temperature inside a raceway

electrical wire is made by drawing in it through a succession of_________

dies

Each time a wire is passes through a die, it is wrapped around a________ several times.

draw block

As a general rule, most conductive materials will_______ their resistance with an increase of_______.

increase,temperature

Conductors become more resistive as temperatures______. This reduces the amount of ____they can safely carry.

increases,current

When determining wire size first remove the_____ from the around the conductor.

insulation

circular mil (cmil)

is the cross-sectional area of the wire in miles squared.(one mil = 0.001 inch.)

The national electrical code (NEC)

is used throughout industry to determine the conductor size for most applications.

parrallel conductors

is when the conductor is very large

One of the factors that determine the resistivity of wire is the_____from which is made.

material

If wire tables cannot be used,electrician should know how to determine the conductor size needed by calculating__________.

maximum voltage drop and resistance of the conductors.

conductors of a single phase are not permitted to be run in _________.

metalic conduit

An electric duct can be a signal _____ or _____ condict.

metalic nonmetalic

Materials that decrease their resistance with an increase of temperature have a______ coefficient of temperature.

negative

Materials that increase their resistance with an increase of temperature have a______ coefficient of temperature.

positive

Long wires runs have the effect of adding____in series with the load.

resistance

If conductors are to be use in a location that has a higher ambient temperature,

the ampacity of the conductor must be reduce,because the resistance of cooper or aluminum increases with an increase of temp

Maximum operating temperature

weather the Insulation can be use in wet,damp, or dry locations, materials,thickness and outer coverings

A good thing to remember is that insolations materials that contain the letter W, such as RHW,THW,THWN, may be use in ___________.

wet locations.

continous load is (multiply by 1.25%)

where the maximum current is expected to continue for more than three hours or more.[ex:industrial motors and lightning loads