Thread: Solar input to existing accessory cable

Originally Posted by Old Farang

Genuine question:

Ok you auto electric types, please explain why auto cable is being quoted by what appears to be the OD of the insulation, and not the mm2 of the conductor. I trained as an electrical fitter / armature winder where wire sizes were often quoted in different sizes, such as B&S, SWG and if stranded the old English types such as 23/0076 or similar where we fitted flexible leads to the windings.

Automotive cables are available with different thickness insulation, so how do you class a cable by how thick the insulation is?
I spent years working with American cable sizes, which are completely ridiculous! Some of the cables that I worked with were supplying 800hp DC traction motors, but the OD of the insulation had nothing to do with amp carrying capacity, although the insulation material itself was classed for the operating conditions.

I also thought that Australia had converted to metric in all things, under threat of legal action if not followed! So again, why are cables not obliged to be quoted in metric sizes, rather than B&S(AWG)? Cheers

Auto cabling rating is normally in amps, and that amps is amps at a measured temperature of the wire.

someone worked out that if you use slightly thinner wire, slightly more plastic you get the same sheath temp for less money for a given number of amps passing through a given distance of wire.

I could get into the boring thermodynamics of it but meh...

If you want simple proof of it..

look at the size of the "wire" in a 20A fuse and then compare that to the same size wire you should use to carry 20a.

Originally Posted by Blknight.aus

Auto cabling rating is normally in amps, and that amps is amps at a measured temperature of the wire.

someone worked out that if you use slightly thinner wire, slightly more plastic you get the same sheath temp for less money for a given number of amps passing through a given distance of wire.

I could get into the boring thermodynamics of it but meh...

If you want simple proof of it..

look at the size of the "wire" in a 20A fuse and then compare that to the same size wire you should use to carry 20a.

Thank you, and that does absolutely nothing towards answering the question!