A1 Lt 15, 17, 18 Flashcards
(23 cards)
1 mil is equal to
1/1000th of an inch
How do you find CMA
the diameter of the wire in mils squared
MCM and KCM are how many CM
1000 CM
What is bigger 1 CM or 1 SM
1 SM (square mil)
What is the factor used to convert CMA to SMA
0.7854 or π/4
What is the SM or a conductor with a diameter of 25 mil
491 SM
First step when trying to find CMA or SMA
Always convert to mils first
To find the CM of a stranded conductor you must
find the CM of one strand and then multiply it by the number of strands
The biggest AWG size is
4/0 or 0000 AWG
The larger the AWG # the ______ the resistance
greater
What is the ratio (in CM) between one AWG number
1.26
What happens to the CMA every time the AWG changes by 3 numbers
CMA is either doubled or halved
What is the approximate CMA of #10 AWG
10000
What is ampacity
“Ampacity refers to the rated current carrying capacity of a conductors.”
allowable ampacity of a conductor varies according to
Type of conductor (aluminum or copper)
Size of conductor
Temperature rating of Insulation
Whether conductor is installed in free air, raceway or cable
The surrounding air (ambient) temperature
The number of conductors in contact with each other (i.e. in a conduit or cable and where conductors are placed close to others)
What is coppers resistivity
10.4
What is aluminums resistivity
17
What tables deal with copper conductors ampacity
Tables 1 and 2
What tables deal with aluminum conductors ampacity
Tables 3 and 4
What table for the ampacity of flexible cord
table 12
What table for the ampacity of neutral supported cable
tables 36 a and b
Line loss is the loss of ____
Power
Line drop is the drop of ____
Voltage
