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Wire length tables

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Introduction[edit]

Describe wire length, voltage loss, etc. here.

Tables[edit]

The following table shows the American Wire Gauge (AWG) size for several different round trip (RT) wire lengths based on maximum current (A) for a 12V DC system (assuming 3% maximum wire loss):

Table 1. Wire Sizes
RT length 5A 10A 15A 20A 25A 30A 40A 50A
15 ft 16 12 10 10 8 8 6 6
20 ft 14 12 10 8 8 6 6 4
25 ft 14 10 8 8 6 6 4 4
30 ft 12 10 8 6 6 4 4 2
40 ft 12 8 6 6 4 4 2 2
50 ft 10 8 6 4 4 2 2 1
60 ft 10 6 4 4 2 2 1 1/0
70 ft 8 6 4 2 2 2 1/0 2/0
80 ft 8 6 4 2 2 1 1/0 2/0
90 ft 8 4 2 2 1 1/0 2/0 3/0

This table was adapted from Engineering Toolbox [1] .

Calculating Wire Sizes[edit]

Assumptions made:

  1. copper wire resistivity = 11.2 [2]
  2. 3% loss from wires
  3. allowable voltage drop = 0.36V
    • 12V system, 3% (0.03) wire loss -> 12V x 0.03 = 0.36V

Variable Declarations:

  • An: circular mil area
  • n: AWG
  • m: AWG
  • Conductor resistivity: constant, 11.2
  • Current: current through wire in Amps, acquired from table
  • Roundtrip (RT) wire length: complete length of wire, ft, acquired from table
  • Allowable voltage drop: voltage drop through wires, V
Table 2. Calculating Wire Sizes
Eqn. # Equation Step/Explanation
#1 [math]A_n=(5*92^\frac{36-n}{39})^2[/math] Eqn. 1 was used, rearranged, and iterated on to produce Table 1. [3].
#2 [math]n=36-\frac{39*log\sqrt{\frac{A_n}{5}}}{log(92)}[/math] Algebraically rearrange Eqn. 1 to solve for n. The resulting equation is Eqn. 2 to the left.
#3 [math]n=1-m[/math] If n<0, replace n with 1-m in Eqn. 1 [4] .
#4 [math]A_n=(5*92^\frac{36-(1-m)}{39})^2[/math] Substituting n equals 1-m into Eqn. 1 yields this equation (Eqn. 3). Use Eqn. 3 if n<0.
#5 [math]m=\frac{39*log\frac{\sqrt{A_n}}{5}}{log(92)}-35[/math] Solve Eqn. 3 for m, the resulting equation (Eqn. 4) is to the left.
#6 [math]A_n=\frac{(conductor-resistivity)*(current[A])*)roundtrip-wire-length[ft])}{allowable-voltage-drop[V]}[/math] Eqn. 3 is also a rearrangement of Eqn. 1. Use Eqn. 4 to solve for A_n


See Help:Tables.

Use help:references to see how to use the reference format.[1]

Use Help:Images on how to upload the graph image(s). Please remember to use a very descriptive name for the file.

References[edit]

  1. It is quite easy and just relies on ref and /ref in between less than and greater than symbols.