# question

## 70mm2 cable diameter.

Hi everybody,

I have purchased some 70mm2 cable for connecting victron quattro and mppt 450/100. when i have measured the cable it is 15mm across including the sheathing. the fine strand wire inside is 10mm across. is this correct or should the wire be more like 15mm across and 19mm with sheathing.

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15mm diameter including the sheathing sounds right to me and is very similar to my own 70mm2 cable. In terms of the conductor diameter, you can work backwards from the formula:

So radius = sqrt ( CSA / Pi ) = sqrt ( 70 / 3.14 ) = 4.72mm

So diameter = 2 x radius = 9.44mm

This isn't exact because the individual fine strands are usually circular and therefore there is some gaps between the strands and so the diameter will be slightly larger than this 9.44mm figure.

This is the cable I use: https://www.12voltplanet.co.uk/extra-flexible-tinned-copper-pvc-battery-cable-70mm-485a.html (listed as 15.5mm outside diameter including sheath)

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Hi .

thanks for your reply, I also purchased my cable from 12v planet but I am a little confused as to the correct specification of 70mm2 wire.

0 Likes 0 ·
liam-italy ·

The recommended cable is fine strand of correct mm², which looking at the spec from 12 planet link is good and meets the requirements with the extra feature of tinned for corrosion.

They just need to be (double insulated) flexible and carry the current, be terminated correctly.

If you want to know more about cable selection and set up there is a neat book here.

1 Like 1 ·
Alexandra ♦ ·
I'm also using this cable in my boat, it's not double insulated.
1 Like 1 ·

Than you for your reply, reassuring that you both consider the specs up to standard. there are no markings on the sheathing that was another thing that bothered me.

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I used the orange welding flex and the spec sheet for that says 70mm is 11.7mm in diameter. 50mm is 9.8mm. Have you tried sliding a lug on?
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the-doon ·
I have crimped 70mm lugs on and to be honest they are good, was only later that i had doubts.
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