once again, auto, audio, trade != industry.
give triangle cables a ring, thats an ozzy company that i used to deal with, you buy your cable from them based on mm2 of copper, you do it that way because thats what you need, not a size. industrial cables, as in non pretty heavy duty ones, often have harder thinner insulation, and thicker strands (still flex).
the guage used in audio is usually the awg scale, which was linked to from your link.
it shows 4awg as having 21.2mm whereas if you buy "4 guage" from dick smith, its under 18... its the same with a lot of the flashy audio crap. that and the plastic is not very good with chemicals, just looks good with neons and other wanker [shizzle] like that.
i'm not arguing that what you have used is no good, or not big enough, just that its an inaccurate way of saying it, whether it should be or not...
for the record, according to the awg page 0 guage is 53.5mm, which is more than what i used. in practice you may have recieved less. perhaps link your suppliers, so we can see what you actually got for you zero guage money.
my supplier was BOC, and heres what the stiff rugged [shizzle] looks like :
http://i50.photobucket.com/albums/f3...4/100_4182.jpg
note the size of the battery post relative to the insulation
http://i50.photobucket.com/albums/f3...4/100_4207.jpg
for industry, in mm squared.
http://i50.photobucket.com/albums/f3...4/100_4208.jpg
http://i50.photobucket.com/albums/f3...4/100_4209.jpg
thats some audio spec "8 guage" there next to it, roughly 7mm2 when it should have been about 8 or so...
http://i50.photobucket.com/albums/f3...4/100_4214.jpg
but i'm sure its enough for a couple of fuel pumps, a megasquirt feed, and an alternator charge lead ;-)
link your brands so we can see what you got for your cash :-)
fred.