# Which diameter of two core cable?

1. May 4, 2012

### blimthepixie

Hello all,

First time here and first time posting. Just like to say a quick hello before getting started...

Due to the rise of solar PV panels being installed before the Feed in Tariff was cut earlier this year (in the UK) I've been thinking about the cable losses that these incur.

Imagine a relatively small, 5 kW system with a peak power rating of 175W (and 5A). This array is 30m from the control electronics and is using 2-core cable. (Copper having a resistivity of 1.69 x 10^-6 m^3).

What cross sectional area of cable will be needed to keep power loss in the cable to around 10%?.

Thanks in advance for taking a look at this and if I've negated to mention anything important just let me know...

2. May 4, 2012

### Bob S

Use this copper wire resistance table http://www.powerstream.com/Wire_Size.htm
For example, 14 Ga. copper wire is rated at 5.9 amps max, and has a resistance of 2.5 ohms per 1000 feet. So for 30 meters = 100 feet, the power loss is I2 R = 52·0 .25 = 6.25 watts.

3. May 5, 2012

### Bob S

Sorry. This is for only one conductor. Two conductors represent 12.5 watts.