Lesson 2: How Building Wire is Sized

Match the following inches to their correct conversion in mils.

0.25 inches = mils = II. 250 mils. 0.125 inches = mils = I. 125 mils. 1/4 inch = mils = II. 250 mils 3/4 inch = mils = III. 750 mils

Match the circular mil area of the following wire sizes.

10 AWG circular mil area = III. 10,380 cm 8 AWG circular mil area = IV. 16,510 cm 6 AWG circular mil area = V. 26,240 cm 14 AWG circular mil area = I. 4,110 cm 4 AWG circular mil area = IV. 16,510 cm 12 AWG circular mil area = II. 6,530 cm

A person has a piece of wire that is 12 strands of 118.3 mils diameter. What is the approximate size of wire? This is the second step in a three step process. You will need this answer for the next question. Second Step: Multiply circular mil area by number of strands.

13,995 × 12 = 167,940 cmil The correct answer is: 167940

A person has a piece of wire that is 12 strands of 118.3 mils diameter. What is the approximate size of wire? This is the third and final step in a three step process. Third Step:Use Chapter 9, Table 8 of the Code to locate size closest wire size.The AWG for a wire made up of 12 strands that is 118.3 mils diameter is ? .

167,800 cmil = 3/0 The correct answer is: AWG 3/0

What is the circular mil area of wires having the following diameters?

500 mils = circular mil area = VII. 250,000 10 mils = circular mil area = II. 100 0.1020 inch = circular mil area = V. 10,404

Match the following mils to their correct conversion in inches.

500 mils = inches = VI. 1/2" 375 mils = inches = V. 3/8" 750 mils = inches = VII. 3/4" 187.5 mils = inches = II. 3/16"

Match the conductors to the ampacity that indicates the allowable current-carrying capacity.

Amperes for 3 1/0 AWG, THW, copper in conduit = 150 Amperes for a single 1/0 AWG, THW, copper conductor in free air = 230 Amperes for 3 1/0 AWG, THW, aluminum in conduit = 120 Amperes for a single 1/0 AWG, THW, aluminum conductor in free air = 180

A person has a piece of wire that has 12 strands, each strand with a diameter of 118.3 mils. To determine the size of wire will require three steps. The first step is to calculate the circular mil area for each strand. What is the circular mil area of each strand? (Round the FINAL answer for this question to the nearest whole number.)(Note: The answer calculated for this question will be used for additional questions.)

CMA = d2 CMA = 118.32 CMA = 13994.89 circular mils CMA = 13995 circular mils The correct answer is: 13995

In reference to wire size, AWG stands for American Wire Gauge.

True

The ? of a conductor is defined as the diameter of the conductor in mils, squared.

a. circular-mil area

Using the approximate resistance method, what is the resistance of 3,302 feet of 8 AWG copper wire that has a circular mil area of 16,510?

b. 2 Ω

What is the resistance of 1,000 feet of No. 14 copper wire? Use given properties. Given: copper = 10.4 ohms per circular mil foot No. 14 wire circular mil area = 4,110 cmil

b. 2.53 Ω

The largest size wire listed in wire gauge number is ?

b. 4/0

The allowable ampacities in Table 310.16 and Table 310.17 are based on an ambient temperature of ? .

b. 86°F

Which formula is used to find circular mil area?

b. Acmils = dmils2

What might happen to thermoplastic insulation at temperatures colder than -10°C (+14°F)?

b. The insulation might stiffen.

There are no color coding requirements for grounded conductors found in the NEC.

b. false 200.6

Write out in words what 250 kcmil means.

b. two hundred and fifty thousand circular mils

What length of 12 AWG copper wire would be required to produce a resistance of five ohms? (Use the approximation method.)

c. 3,265 feet

How many strands of 10 AWG wire would it take to make a 500-kcmil cable?

c. 49

In general, all conductors ? AWG and larger, installed in a raceway, shall be stranded.

c. 8 310.3(C)

Which formula determines the resistance of a conductor?

c. Rohms = K × Lfeet / ACM

To find the approximate resistance of a given copper conductor, drop the ? digit from the circular mil area. The result is the number of ? per ohm.

c. last / feet

In general, the smallest size conductor permitted for 2,000 V is ? AWG copper or ? AWG aluminum or copper-clad aluminum.

d. 14 / 12 310.3

To find the area of a wire in circular mils, square the diameter expressed in ? .

d. mils