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Voltage Loss Tables for AWG Wire

Voltage Loss Tables for AWG Wire

Wire Loss Tables for Solar Electric Systems

Includes 12, 24, and 120 volt charts and a metric to AWG size conversion table.

This is a five percent table which means at these amperage ratings at the listed distances, 5% of the power would be lost to resistance. Five percent is normally acceptable in low voltage systems, but if you want a 2% figure, divide the given distances by 2.5. For a 10% loss multiply the distance by 2. For distances at 48 volts, double the 24 volt distances for a 5 percent loss figure. For 240 volt 5% loss, double the 120 volt distances. These distances include the NEC requirement for current over sizing of 25%.

Example: For a pump drawing 9 amperes at 24 volts, located 88 feet from the battery bank: look at the center table for 24 volts. In the far left column find the next number higher than 9 (which is 10) and follow that line across the table until you find a distance figure greater than 88. At the top of the column find the gauge of wire (#6) that should be used. This method insures that wire losses are kept to an acceptable level without spending too much money on extra-heavy cable. Using a heavier wire than indicated, however, will result in even higher efficiencies and we do sometimes invest in the next larger gauge. Wire can get expensive, and it may not be worth the money to get that last 1% if you have to go to a much larger wire size.

Some of the newer grid tie systems inverters, such as the Sunny Boy, use up to 600 volts DC. Generally in these systems loss in wire is nothing to worry about. HOWEVER - you will have to be more careful about selecting and installing the wiring - high voltage DC is not something you want to do a 2nd rate wiring job on. Make sure the insulation is rated for 600 volts, and that there is no damage to the wire or insulation.

All distances are in FEET

Do not use any wire sizes that might fall into the red zone - this would exceed the amperage rating of the wire and it may overheat and burn.

120 Volts AC or DC Chart

Amps in Wire Watts at 120V #14 #12 #10 #8 #6 #4 #2 1/0 2/0 3/0
2 240 422 656
4 480 187 328 516
6 720 141 225 328 562
8 960 103 159 272 422 666
10 1200 84 131 216 337 534
15 1800 56 84 131 225 356 562
20 2400 65 103 168 272 422 675
25 3000 84 131 216 337 543
30 3600 65.63 112 178 281 450 722
40 4800 84 131 216 337 543 675
50 6000 67 103 171 272 431 543 684

24 Volts DC Chart

Amps
in Wire
Watts
at 24V
#14 #12 #10 #8 #6 #4 #2 1/0 2/0 3/0
1 24 169 262 412 675
2 48 84 131 207 337 532  
4 96 37 66 103 169 267
6 144 28 45 66 112 178 282  
8 192 21 32 54 84 133 216
10 240 17 26 43 67 107 169 270
15 360 11 17 26 45 71 112 180 289
20 480 13 21 37 54 84 135 217 270 343
25 600 17 26 43 67 108 172 217 274
30 720 13 22 36 56 90 144 180 228
40 960 17 26 43 67 108 135 171
50 1200 13 21 34 54 86 108 137

12 Volts DC Chart

Amps in Wire Watts at 12V #14 #12 #10 #8 #6 #4 #2 1/0 2/0 3/0
1 12 84 131 206 337 532  
2 24 42 66 103 168 266 432 675      
4 48 18 33 52 84 133 216 337 543 675  
6 72 14 22 33 56 89 141 225 360 450 570
8 96 10 16 27 42 66 108 168 272 338 427
10 120 8.5 13 22 33 53 84 135 218 270 342
15 180 6 8.5 13 22 35 56 90 144 180 228
20 240   6.6 10 16 27 42 67 108 135 171
25 300     8 13 22 33 54 86 108 137
30 360     6.6 11 18 28 45 72 90 114
40 480       8 13 21 33 54 67 85

These are one-way distances, measured from point A to point B. The out and back nature of electrical circuits has already been included. For PV arrays, figure the entire run, from the panels to the charge controller to the batteries


Cross Reference of AWG (American Wire Gauge) Sizes to Metric (mm)

AWG mm2   AWG mm2   AWG mm2   AWG mm2
30 0.05 18 0.75 6 16 4/0 120
28 0.08 17 1.0 4 25 300MCM 150
26 0.14 16 1.5 2 35 350MCM 185
24 0.25 14 2.5 1 50 500MCM 240
22 0.34 12 4.0 1/0 55 600MCM 300
21 0.38 10 6.0 2/0 70 750MCM 400
20 0.50 8 10 3/0 95 1000MCM 500


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