Conductor Requirements Flashcards
most common conductor
materials used in building electrical wiring, although
other materials can be used.
Copper and aluminum
are used in
small conductor sizes (up to about ______) because
safety issues associated with aluminum are avoided and
weight and cost are not significantly affected.
solid copper conductors, 8 AWG
are widely used on
larger (above _____) circuits serving large motors,
equipment, and appliances
‘Stranded aluminum conductors, 30 A
Electronic circuits and phone extensions
No. 20 AWG and smaller
Light-gauge extension cords, lamp cords, door chime wiring, small appliance cords
No. 16 to 18 AWG
Normal 15 A and 20 A branch circuits serving small appliances, convenience (receptacle) outlets,
and luminaires
No. 12 to 14 AWG
Larger branch circuits at 30 A and above serving electrical appliances such as electric water heaters, clothes
dryers, air conditioning equipment, and water pumps
No. 4 to 10 AWG
Residential and light commercial service entrance conductors and feeders to panelboards
No. 2 to 4/0 AWG
Heavy commercial and industrial service entrance conductors, large feeders to closet transformers,
and panelboards
250 kcmil and larger
covered with insulation to provide
electrical isolation and physical protection of the
conductor material.
Conductors
determines the
environment in which a wire or cable can be used safely.
type of insulation material
are used as a
covering for electric wires.
Insulators like plastic and
rubber
may need to be adjusted with correction
factors when conditions related to the temperature of the
Surroundings and the number of conductors in a
raceway (e.g., conduit or cable) fall outside normal
operating ranges.
ampacity of a
conductor
Armored cable with conductors having thermoset insulation. 194°F (90°C) temperature rating.
ACHH
Armored cable with conductors having thermoplastic insulation. 167°F (75°C) temperature rating.
ACTH
Armored cable with conductors having thermoplastic insulation. 194°F (90°C) temperature rating
ACTHH
Non-metallic sheathed cable. 140°F (60°C) temperature rating. Approved for use in dry, interior residential wiring if properly
installed inside framed walls, floors, and ceilings. Not sunlight resistant.
NM
Underground feeder. 140°F (60°C) temperature rating. Generally not sunlight resistant, unless marked.
UF
Underground service entrance. 167°F (75°C) temperature rating, wet insulation rating, heat and moisture resistant. Sunlight
resistant.
USE
Underground service entrance. 194°F (90°C) temperature rating, wet insulation rating. Heat and moisture resistant. Sunlight
resistant.
USE-2
Use to convey power from the service drop to the meter base and from the meter base to the distribution panelboard.
cable
__________ for each conductor size are for different
equipment terminal (where connections of wiring are
made) temperatures.
Ampacity values
_______________ at the equipment terminals can damage
the conductors if it is not properly dissipated.
Heat generated
is the temperature of a
Surrounding medium (e.g., air, Soil).
Ambient temperature
As ambient temperature rises, less current generated
heat is needed to reach the temperature rating of the
insulation. Therefore, ampacity is governed’ by
contribution of ambient heat.
TRUE
refers to
the normal temperature range in the environment in which
that conductor is to be used (e.g., the temperature of the
Surrounding air, water, or earth).
ambient temperature rating
adjusted for changes in ambient
temperature, including temperatures below 78°F (26°C)
and above 86°F (30°C).
Conductor ampacity
applied based on the ambient temperature of the
conductor
temperature correction factor (F, )
When several current-carrying conductors’ are
contained in a ___________, the temperature of the
conductors will increase under ______________
raceway or cable, normal loading
conditions.
must be applied for
four or more conductors in a raceway or cable installed
in the same raceway or conduit or any bundled cables
that are more than ____________.
bundling correction factor (Fy) , 24 in (0.63 m) long.
In addition to ampacity requirements, _________ and
_________ should be analyzed for voltage drop because of
the adverse effect it can have on performance and
operating life of appliances and equipment.
branch circuits, feeders
Total voltage drop in the feeders and branch circuits
should not exceed ____.
5%
The percentage of voltage drop is determined by the ratio
of ________ and __________.
ratio
of voltage drop, system voltage
The basic formula for determining voltage drop (Edrop) in
a two-wire AC circuit or three-wire AC single-phase circuit
with a balanced load at 100% power factor (neglecting
reactance) is based on the ____________, in
feet or meters; __________, in Q/1000 ft or
Q/1000 m; and ____________ in amperes:
one-way circuit length (L), conductor resistance (R), the circuit load
In SI (metric) computations, substitute the constant
70.8 for ____ and 118 for ___ to find length (L) in meters.
21.6, 36
In SI (metric) computations, substitute the constant
61.3 for _____ and 102.2 for _____ to find length (L) in meters.
18.7, 31.2
_________ on small- and medium-size conductors is
color coded for identification.
insulation
_______ requiring color identification are
marked at the terminal ends with a _______ or
________ wrapped around the conductor insulation.
Larger conductors, hand-painted stripe, colored tape
The grounding (ground) conductor insulation must be
color coded _____, ______ with ________, or may be a bare conductor on small conductors
in cables.
green, green, one or more yellow
stripes,
The _________ standard for color coding is ______ or any
color, except ___________ (ungrounded/hot); ______
(grounded/neutral); and ____ (ground).
North American standard, black, white, gray, and green, white, green
¢ Grounded neutral, white (first or only neutral in raceway, box, auxiliary gutter, or other types of enclosures)
¢ Grounded neutral, white with black stripe running entire length of insulation (when neutral is installed in raceway,
box, auxiliary gutter, or other types of enclosures with another neutral)
¢ Grounding conductor, green, green with one or more yellow stripes, green tape, or bare
¢ Ungrounded conductor, black with “120V-1PH”” marking
120V AC
single phase,
two wire
-Grounded neutral, white (first or only neutral in raceway, box, auxiliary gutter, or other types of enclosures)
-Grounded neutral, white with brown stripe running entire length of insulation (when neutral is installed in raceway, box,
auxiliary gutter, or other types of enclosures with another neutral)
-Grounding conductor, green, green with one or more yellow stripes, green tape, or bare
-Ungrounded conductor, black with “240/120V-1PH-A” marking
-Ungrounded conductor, red with “240/120V-1PH-B” marking
120/240 V AC
single phase,
three wire
Grounded neutral, white (first or only neutral in raceway, box, auxiliary gutter, or other types of enclosures)
Grounded neutral, white with red stripe running entire length of insulation (when neutral is installed in raceway, box,
auxiliary gutter, or other types of enclosures with another neutral)
Grounding conductor, green, green with one or more yellow stripes, green tape, or bare
Phase X (ungrounded) conductor, black with “208Y/120V-3PH-X” marking
Phase Y (ungrounded) conductor, red with “208Y/120V-3PH-Y” marking
Phase Z (ungrounded) conductor, blue with “208Y/120V-3PH-Z” marking
208 Y/120 V AC
three phase,
four wire
Grounded neutral, white (first or only neutral in raceway, box, auxiliary gutter, or other types of enclosures)
Grounded neutral, white with yellow stripe running entire length of insulation (when neutral is installed in raceway, box,
auxiliary gutter, or other types of enclosures with another neutral)
Grounding conductor, green, green with one or more yellow stripes, green tape, or bare
Phase X (ungrounded) conductor, brown with “480Y/277V-3PH-X” marking
Phase Y (ungrounded) conductor, orange with “480Y/277V-3PH-Y” marking
Phase Z (ungrounded) conductor, yellow with “480Y/277V-3PH-Z” marking
480 Y/277 V AC
three phase,
four wire
Grounding conductor, green, green with one or more yellow stripes, green tape, or bare
Phase X (ungrounded) conductor, black with “240VD-3PH-X” marking
Phase Y (ungrounded) conductor, black with “240VD-3PH-Y” marking
Phase Z (ungrounded) conductor, black with “240VD-3PH-2Z” marking
240 delta/120 V AC
three phase,
three wire
Grounding conductor, green, green with one or more yellow stripes, green tape, or bare
Phase X (ungrounded) conductor, brown with “480VD-3PH-X” marking
Phase Y (ungrounded) conductor, orange with “480VD-3PH-Y” marking
Phase Z (ungrounded) conductor, yellow with “480VD-3PH-Z” marking
480 delta V AC
three phase,
three wire
