Chinasky Tips on the Evaluation of Power Loss of Power Extension Cables

In CCTV application, power extension cables are commonly seen to be used with power adapter 12V5A or 12V3A. Sometimes our customers find it difficult to decide which adapter, which awg of cable or which length of cable to use in consideration of power loss to different extent on cables of different specification. Here Chinasky would like to share with you our thoughts on how to evaluate the power loss.

The resistance value for 18awg cable is 0.0214Ω/m.

The resistance value for 20awg cable is 0.0339Ω/m.

Power(P)=I(Current)²*R(Resistance)

Therefore, theoretically we can calculate the value of power loss if we assume the current(I) is the full-load value: 5A with 12V5A adapter, and 3A with 12V3A adapter.

1. 12V5A adapter + 20awg DC extension cable:

10feet: 3.05m, power loss is 0.0339x3.05x5²=2.59W

20feet: 6.1m, power loss is about 5.17W

30feet: 9.15m, power loss is about 7.76W

2. 12V5A adapter + 18awg DC extension cable, power loss for:

10feet: 1.63W

20feet: 3.27W

30feet: 4.9W

3. 12V3A adapter + 20awg DC extension cable, power loss for:

10feet: 0.93W

20feet: 1.87W

30feet: 2.8W

4. 12V3A adapter + 18awg DC extension cable, power loss for:

10feet: 0.59W

20feet: 1.18W

30feet: 1.77W

Please note the above results are the value in theory. They can be used for reference when you are trying to decide which AWG to use, 18awg or 20awg. In actual application, however, power loss can also be caused to different extent with the use of different power adapters (the output cable of power adapters might be different in AWG) and during the connection of connectors. Power loss value is also different when the cable is connected with different equipment (requires different power, and the actual value of current (I) is different.)