Cable Gage between Panels and Batteries

[DigitalMind]

I'm a little confused.  

I understand what wiring I need between the batt. and inverter, and between the inverter and electrical panel.  I'm not sure about the cable between the Solar Panels and batteries though.  

The length of cable between the panels and batteries is about 60 feet.  The panels are only 15 watts (I have 2 X 15 Watts.)  The panels come with about 10 feet of cable, and the manual says I can extend it another 50 feet with 16 Gage cable.  Does that make any sense ?

Also, last question, I am a cable guy for telephone / networks so I have TONS of data cable.  (Which is 24 gage, and has 4 pairs in each cable)  Could I twist all 8 of those conductors together and use 1 cable for + and 1 cable for - ??  Anyone know what GAGE that would be equal too ?  

Hope this made sense .. let me know if I neglected to give some piece of information.

Thanks as always for your help, you've all been great !

[Flux]

Yes those 8 strands in parallel would be about #15 and that should be ok for those little panels.

Flux

[ghurd]

For 5% loss, 2A, 66', using #12.  #10 would be a little better.

The data cable won't cut it very well.  8 strands of #24 is about like #15 (?), meaning a bit too small. Might try 12 strands per side.

http://www.windsun.com/Hardware/Wire_Table.htm

If you will be expanding the system, might as well run the proper wire now.

Might be worth considering SE AL (in a larger gauge).

G-

[DigitalMind]

Thanks Ghurd and Flux,

   I'll follow your advise and put 2 Data cables per side, so it'll be 16 strands of  #24 per side. This cable costs almost nothing to me, so it's kinda worth it.  PLUS, when the snow melts, we'll be digging a trench and running the cable underground, so if they have the budget for it, we can replace it then.  

I'll go look at the cost of the #10 cable though to see ...  Maybe it's cheaper than I think ..

 

[DanG]

A minute with google got this estimation calculator that will even mix conductor sizes for multiple strand wire runs to calculate AWG. I think its a pretty neat tool - glad to have found it!

http://home.hiwaay.net/~rgs/awgcalculator.html

Notes

    * These calculators don't do any fancy math. They just consult a table of cross-sectional areas for a set of common wire gauges. That means that any reported effective gauges are not exact. To find the effective gauge of a collection of wires, their total combined area is computed, and the closest matching entry in the table yields the result. If you look at the browser's status bar, you can see how the result was determined.

    * I used the cross-sectional areas from http://www.thepanelshop.com/Wire_table.htm. There is a similar table (and much other useful and interesting audio information) at http://www.tnt-audio.com/clinica/awg_e.html, but there is a minor mistake in this table. It shows the same diameter and area for 3 and 4 gauge wire.

    * This web page is self-contained, and you can copy it to your PC so you can use it without connecting to the Internet. Just use your browser's Save As... command to save the page to a local file. Then open your local copy in your browser to use the calculators. (Ron Stewart, author)