Solar cable size?????

Patto44 · Senior Member

Solar cable size?????

ozjohn · Guru

6 B&S is 13.5mm(Sq) cable.
The B&S stands for Brown & Sharpe who were an American Engineering Company.
Their wire sizes became the standard for AWG (Amerigan Wire Guage).
Cheers, OJ

Patto44 · Senior Member

Thanks OJ.
Now it makes more sense. 13.5mm is obviously a lot more suitable. The guy that gave me a quote assured me that 6mm auto cable was ample as the panels only have 4mm cable coming out of them.
If he does not want use 6 B&S he won't get the job.
Cheers,
Patto

ozjohn · Guru

Mate,
I only answered the question of what 6 B&S cable is, not what should be used on solar panels.
6 mm auto cable or even smaller may be OK as the amperage from Solar Panels is pretty low.

But like you, I think it's best to wait for a reply from a qualfied member who knows what they're talking about.

Cheers, Ozjohn.

PS> have a search on this site for solar info. www.caravanandmotorhomebooks.com/books/index.htm Then look in 'Articles'

-- Edited by ozjohn on Wednesday 27th of July 2011 07:42:29 PM

-- Edited by ozjohn on Wednesday 27th of July 2011 07:44:51 PM

-- Edited by ozjohn on Wednesday 27th of July 2011 07:45:38 PM

bill12 · Guru

Bigger is better, as there is less resistance in bigger copper cable. Use the biggest copper cable you can afford.

blaze · Guru

Also dont think that thicker copper strands is better either, finer strands and more is better. Less loss over distance.
cheers
blaze

landy · Guru

Try doing a search for a site called hobohome, there is a heap of info there on wire size for solar panels, as well as a lot of other usefull info. Well worth a read.

Landy

PeterD · Guru

From this site we get the formula:

Voltage drop = (cable length (in metres) X current (in amps) X 0.017) divided by cable cross-section in mm.sq.

You can safely have a 1 V voltage drop in the cables fom your panels to your regulator. Your panels will put out a maximum current of around 14 A. Let us assume that your cable length is 10 metres (and you double this as you are not using an earth return,)

We can transpose the formula to get:

Cable size = (cable length (in metres) X current (in amps) X 0.017) divided by 1

Therefore Cable size = 20 x 14 x 0.017 = 4.76 squ mm.

This equates to the size of coper in a 6 mm auto cable (the ones I have actually have 4.8 squ mm of coper in them.) There is no standard for the amount of copper in auto cables. If you read through the article I gave the link for, you will see the actual amount of cable the authour measured in several samples of 4 mm auto cable. All Australian standards quote sizes in square milimetres of copper. The auto and solar industries tend to use American sizes of cable.

-- Edited by PeterD on Thursday 28th of July 2011 12:37:54 AM

jimricho · Guru

I'm no "expert" on solar installations but I would be inclined to think that the "6mm" twin cable available from a marine supplier such as Bias or Whitworths would be fine for the job. The marine type cable is tinned and less prone to corrosion due to exposure to the elements over time.

Clare46 · Senior Member

http://www.hobohome.com

Link for hobohome site. Lots of info

PeterD · Guru

jimricho wrote:
but I would be inclined to think that the "6mm" twin cable available from a marine supplier such as Bias or Whitworths would be fine for the job. The marine type cable is tinned and less prone to corrosion due to exposure to the elements over time.

That would be my choice of cable. I would pump for 6 squ mm cable as it goes one stage bigger in size than what I calculated. Also as jim said, tinned copper cable is better for exposed locations. If you do happen to get moisture in, the wire will not get verdigree and rot out.

Patto44 · Senior Member

Thanks for all the info.
I am still sifting through the links etc. and trying to make the right decision. Hobohome is an informative site.
Been advised that to instal with 6 B&S is only an extra $80. so will go with that just to make sure.

Cheers
Patto