Landscape Low Voltage Lighting
The voltage losses in the chart below were calculated using Ohm's Law, and are
theoretical. Safety margin should be built into the design to take into consideration
deterioration of wire splices, power brownouts, etc.
CONSULT THE MANUFACTURER OF THE LIGHT FIXTURE FOR MORE DETAIL.
| NOTES: |
1) |
Do not use a cable whose ampacity is less than the rating of the transformer circuit breaker. |
| |
2) |
Chart shows voltage drop for maximum flows of 80% of the cables' ampacities. |
VOLTAGE DROP PER 10 LINEAR FEET OF CABLE
| LAMP POWER FLOWING IN CABLE SECTION (WATTS @ 12V) |
FLOW (AMPS) |
WIRE GAUGE (AWG), CLASS K COPPER |
| 18 |
16 |
12 |
10 |
8 |
| WIRE RESISTANCE (Ohms/10' of cable, both conductors) @ 77 °F (25 °C) |
| 0.1358 |
0.0852 |
0.0336 |
0.0212 |
0.0136 |
| 20 |
1.67 |
0.226 |
0.142 |
0.056 |
0.035 |
0.023 |
| 25 |
2.08 |
0.283 |
0.178 |
0.070 |
0.044 |
0.028 |
| 30 |
2.50 |
0.340 |
0.213 |
0.084 |
0.053 |
0.034 |
| 35 |
2.92 |
0.396 |
0.249 |
0.098 |
0.062 |
0.040 |
| 40 |
3.33 |
0.453 |
0.284 |
0.112 |
0.071 |
0.045 |
| 45 |
3.75 |
0.509 |
0.320 |
0.126 |
0.080 |
0.051 |
| 50 |
4.17 |
0.566 |
0.355 |
0.140 |
0.088 |
0.057 |
| 55 |
4.58 |
0.622 |
0.391 |
0.154 |
0.097 |
0.062 |
| 60 |
5.00 |
0.679 |
0.426 |
0.168 |
0.106 |
0.068 |
| 65 |
5.42 |
0.736 |
0.462 |
0.182 |
0.115 |
0.074 |
| 70 |
5.83 |
0.792 |
0.497 |
0.196 |
0.124 |
0.079 |
| 75 |
6.25 |
0.849 |
0.533 |
0.210 |
0.133 |
0.085 |
| 80 |
6.67 |
0.905 |
0.568 |
0.224 |
0.141 |
0.091 |
| 85 |
7.08 |
0.962 |
0.604 |
0.238 |
0.150 |
0.096 |
| 90 |
7.50 |
1.019 |
0.639 |
0.252 |
0.159 |
0.102 |
| 95 |
7.92 |
1.075 |
0.675 |
0.266 |
0.168 |
0.108 |
| 100 |
8.33 |
- |
0.710 |
0.280 |
0.177 |
0.113 |
|
| 105 |
8.75 |
- |
0.746 |
0.294 |
0.186 |
0.119 |
| 110 |
9.17 |
- |
0.781 |
0.308 |
0.194 |
0.124 |
| 115 |
9.58 |
- |
0.817 |
0.322 |
0.203 |
0.130 |
| 120 |
10.00 |
- |
0.852 |
0.336 |
0.212 |
0.136 |
| 125 |
10.42 |
- |
- |
0.350 |
0.221 |
0.141 |
| 130 |
10.83 |
- |
- |
0.364 |
0.230 |
0.147 |
| 135 |
11.25 |
- |
- |
0.378 |
0.239 |
0.153 |
| 140 |
11.67 |
- |
- |
0.392 |
0.247 |
0.158 |
| 145 |
12.08 |
- |
- |
0.406 |
0.256 |
0.164 |
| 150 |
12.50 |
- |
- |
0.420 |
0.265 |
0.170 |
| 155 |
12.92 |
- |
- |
0.434 |
0.274 |
0.175 |
| 160 |
13.33 |
- |
- |
0.448 |
0.283 |
0.181 |
| 165 |
13.75 |
- |
- |
0.462 |
0.292 |
0.187 |
| 170 |
14.17 |
- |
- |
0.476 |
0.300 |
0.192 |
| 175 |
14.58 |
- |
- |
0.490 |
0.309 |
0.198 |
| 180 |
15.00 |
- |
- |
0.504 |
0.318 |
0.204 |
| 185 |
15.42 |
- |
- |
0.518 |
0.327 |
0.209 |
| 190 |
15.83 |
- |
- |
0.532 |
0.336 |
0.215 |
| 195 |
16.25 |
- |
- |
0.546 |
0.345 |
0.221 |
| 200 |
16.67 |
- |
- |
0.560 |
0.353 |
0.226 |
|
| 205 |
17.08 |
- |
- |
0.574 |
0.362 |
0.232 |
| 210 |
17.50 |
- |
- |
0.588 |
0.371 |
0.238 |
| 215 |
17.92 |
- |
- |
0.602 |
0.380 |
0.243 |
| 220 |
18.33 |
- |
- |
0.616 |
0.389 |
0.249 |
| 225 |
18.75 |
- |
- |
0.630 |
0.398 |
0.255 |
| 230 |
19.17 |
- |
- |
0.644 |
0.406 |
0.260 |
| 235 |
19.58 |
- |
- |
0.658 |
0.415 |
0.266 |
| 240 |
20.00 |
- |
- |
0.672 |
0.424 |
0.272 |