Concept explainers
A 120-volt branch circuit supplies a resistive heating load of 10 amperes. The distance from the panel to the heater is approximately 140 ft. Calculate the voltage drop using (a) 14 AWG, (b) 12 AWG, (c) 10 AWG, (d) 8 AWG copper conductors. See 210.19(A), Informational Note No. 4 and 215.2(A)(1), Informational Note No. 2.
(a)
Find the value of voltage drop in 14 AWG copper wire.
Answer to Problem 35R
The obtained value of voltage drop in 14 AWG copper wire is
Explanation of Solution
Given data:
Supply voltage is 120-volt.
Current is 10 A.
The distance between panel and heater is approximately 140 ft.
14 AWG copper conductor.
Calculation:
Write the expression for voltage drop in single-phase circuit.
Here,
K is the approximate resistance in ohms per circular-mil foot at
I is the current, and
CMA is cross-sectional area of the conductors.
Modify Equation (1) for 14 AWG copper wire.
Refer TABLE 4-7 in the textbook for circular mil area (CMA) for many of the common conductors.
The value of CMA for 14 AWG is 4110.
Substitute
Conclusion:
Thus, the obtained value of the voltage drop for 14 AWG copper wire is
(b)
Find the value of voltage drop in 12 AWG copper wire.
Answer to Problem 35R
The obtained value of the voltage drop for 12 AWG copper wire is
Explanation of Solution
Given data:
12 AWG copper conductor.
Calculation:
Modify Equation (1) for 12 AWG copper wire.
Refer TABLE 4-7 in the textbook for circular mil area (CMA) for many of the common conductors.
The value of CMA for 12 AWG is 6530.
Substitute
Conclusion:
Thus, the obtained value of voltage drop for 12 AWG copper wire is
(c)
Find the value of voltage drop in 10 AWG copper wire.
Answer to Problem 35R
The obtained value of voltage drop for 10 AWG copper wire is
Explanation of Solution
Given data:
10 AWG copper conductor.
Calculation:
Modify Equation (1) for 10 AWG copper wire.
Refer TABLE 4-7 in the textbook for circular mil area (CMA) for many of the common conductors.
The value of CMA for 10 AWG is 10,380.
Substitute
Conclusion:
Thus, the obtained value of voltage drop for 10 AWG copper wire is
(d)
Find the value of the voltage drop in 8 AWG copper wire.
Answer to Problem 35R
The obtained value of the voltage drop for 8 AWG copper wire is
Explanation of Solution
Given data:
8 AWG copper conductor.
Calculation:
Modify Equation (1) for 8 AWG copper wire.
Refer TABLE 4-7 in the textbook for circular mil area (CMA) for many of the common conductors.
The value of CMA for 8 AWG is 16,510.
Substitute
Conclusion:
Thus, the obtained value of the voltage drop for 8 AWG copper wire is
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