Transcript Examination Preparation Two Minute Drill 13

©Ted “Smitty” Smith 2008
 This
speed drill is designed to help you
practice calculations. The slides will
transition in three and one half minutes
instead of two minutes.
 Attempt to answer the questions and then
when the slide show completes, Check your
answer. When you reach the end of the drill
all of the slides will be repeated without the
timer so you will have time to check and
verify your answers at that time.
 Click on the left mouse button to begin.
A
1/0 AWG THHN conductor installed in an
ambient temperature of 103 degrees F. will
have an ampacity of _________.
Copyright 2005 Ted "Smitty" Smith
•
154.70 Amperes
What is the ampacity of a 250 kCMIL aluminum
THW conductor installed in an ambient
temperature of 44 degrees Celsius?
Copyright 2005 Ted "Smitty" Smith
 168.100
amperes
•
What is the volume allowance required for
the following junction box which has a total
of nine 12 AWG THHN conductors entering
the junction box, one of which is an
equipment grounding conductor. The box will
contain one duplex receptacle, has no
internal clamps, and no luminairie studs or
hickeys.
 24.75
•
What is the demand on the main service
entrance of a range that has a nameplate
rating of 240V and 9.5 kW?
 8000
watts
A
load of 23 amperes is being fed by a circuit
consisting of 10 AWG THHN copper
conductors. The conductors are installed in a
conduit that is installed on a rooftop in the
direct sunlight. The conduit is installed 12”
above the roof from the bottom of the
conduit. The average ambient temperature
for the area in which the conduit is installed
is 87 degrees F. The conduit contains a total
of three current carrying conductors. Is this
an acceptable installation?
Copyright 2005 Ted "Smitty" Smith

Yes, it is rated to carry 32.8 amperes.
A
39.6 ampere load is fed with a 6 AWG THW
conductor that is installed in a conduit with a
total of 7 current carrying conductors. The
conduit is installed in a room that has an
ambient temperature 38 degrees Celsius. Is
this an acceptable installation?
 Yes
it is acceptable. The conductor is rated
at 40.04 amperes.
 Three
10 AWG THHN, four 6 AWG THW and
five 8 AWG TW conductors are installed in a
one and one half inch electrical metallic
tubing conduit that is 280 feet in length. Is
this an acceptable installation?
Copyright 2005 Ted "Smitty" Smith
 Yes,
the wires make up a volume of .5722
and at 40% fill an EMT 1 1/4” conduit is
.598.
Copyright 2005 Ted "Smitty" Smith
 What
is the ampacity of 2 AWG TW aluminum
conductor installed in a conduit that is
installed in a boiler room with an ambient
temperature of 103 degrees F and the
conductor is installed in a conduit with a
total of 17 current carrying conductors?
 30.75
Amperes
 What
is the demand on the main service
entrance of a dwelling unit for a range that
has a nameplate rating of 14.5 kW at 240
volts?
 9200
watts
A
4 x 1 ½ square metal box is installed with
two duplex receptacles. The box has a total
of three 12 AWG MC cables entering the box,
each MC cable is a 12/2 with ground. The box
contains no internal cable clamps, and no
luminairie studs or hickeys. Is this an
acceptable installation?
 No,
the conductors and devices require a
volume allowance of 24.75 and Table
314.16(A) lists a 4 x 1 ½” metal box as having
a volume of 21.0
 Is
it allowable to add three 10 AWG THHN
conductors to an existing conduit that is 150
feet in length and currently has eight 6 AWG
THWN conductors and one 12 AWG THHN
conductor installed? The conduit is a 1 ¼”
inch electrical metallic tubing.
 No.
The total area used by the conductors
once the three 10 AWG conductors are added
will be .4822 inches and a 1 ¼” EMT at 40%
fill has an allowance of only .598 inches.
 This
is the end of
the presentation.
 You
can now review
the slides and
answers without the
timer.
 Click
the slide to
advance to the next
slide
A
1/0 AWG THHN conductor installed in an
ambient temperature of 103 degrees F. will
have an ampacity of _________.
Copyright 2005 Ted "Smitty" Smith
•
154.70 Amperes
What is the ampacity of a 250 kCMIL aluminum
THW conductor installed in an ambient
temperature of 44 degrees Celsius?
Copyright 2005 Ted "Smitty" Smith
 168.100
amperes
•
What is the volume allowance required for
the following junction box which has a total
of nine 12 AWG THHN conductors entering
the junction box, one of which is an
equipment grounding conductor. The box will
contain one duplex receptacle, has no
internal clamps, and no luminairie studs or
hickeys.
 24.75
•
What is the demand on the main service
entrance of a range that has a nameplate
rating of 240V and 9.5 kW?
 8000
watts
A
load of 23 amperes is being fed by a circuit
consisting of 10 AWG THHN copper
conductors. The conductors are installed in a
conduit that is installed on a rooftop in the
direct sunlight. The conduit is installed 12”
above the roof from the bottom of the
conduit. The average ambient temperature
for the area in which the conduit is installed
is 87 degrees F. The conduit contains a total
of three current carrying conductors. Is this
an acceptable installation?
Copyright 2005 Ted "Smitty" Smith

Yes, it is rated to carry 32.8 amperes.
A
39.6 ampere load is fed with a 6 AWG THW
conductor that is installed in a conduit with a
total of 7 current carrying conductors. The
conduit is installed in a room that has an
ambient temperature 38 degrees Celsius. Is
this an acceptable installation?
 Yes
it is acceptable. The conductor is rated
at 40.04 amperes.
 Three
10 AWG THHN, four 6 AWG THW and
five 8 AWG TW conductors are installed in a
one and one half inch electrical metallic
tubing conduit that is 280 feet in length. Is
this an acceptable installation?
Copyright 2005 Ted "Smitty" Smith
 Yes,
the wires make up a volume of .5722
and at 40% fill an EMT 1 1/4” conduit is
.598.
Copyright 2005 Ted "Smitty" Smith
 What
is the ampacity of 2 AWG TW aluminum
conductor installed in a conduit that is
installed in a boiler room with an ambient
temperature of 103 degrees F and the
conductor is installed in a conduit with a
total of 17 current carrying conductors?
 30.75
Amperes
 What
is the demand on the main service
entrance of a dwelling unit for a range that
has a nameplate rating of 14.5 kW at 240
volts?
 9200
watts
A
4 x 1 ½ square metal box is installed with
two duplex receptacles. The box has a total
of three 12 AWG MC cables entering the box,
each MC cable is a 12/2 with ground. The box
contains no internal cable clamps, and no
luminairie studs or hickeys. Is this an
acceptable installation?
 No,
the conductors and devices require a
volume allowance of 24.75 and Table
314.16(A) lists a 4 x 1 ½” metal box as having
a volume of 21.0
 Is
it allowable to add three 10 AWG THHN
conductors to an existing conduit that is 150
feet in length and currently has eight 6 AWG
THWN conductors and one 12 AWG THHN
conductor installed? The conduit is a 1 ¼”
inch electrical metallic tubing.
 No.
The total area used by the conductors
once the three 10 AWG conductors are added
will be .4822 inches and a 1 ¼” EMT at 40%
fill has an allowance of only .598 inches.