Wire Size VS Amps

It's still all in British Standard 7671, and has been for years.

In the UK, most installations require trhe issue of a test certificate under the Building Regulations Part P. The nature of the question indicates the original poster does not have sufficient training and experience to carry out correct installations in the UK.

If in doubt, consult a qualified electrician.

NEC table 310.16 http://www.houwire.com/products/technical/article310_16.html

It depends on where you are. North America, use the National Electric Code (or Canadian Electric Code). If you are outside of North America, use the BS (British Standards) or IEC standards for wire ampacity. All of these standards will vary by application; where is it used, how it it used, what is the temperature, etc. etc. Nothing else is relevant.

Here is a nice "generic" wire gage table, along with a voltage drop calculator:

http://www.powerstream.com/Wire_Size.htm

it depends upon which standard you are using..their differences lies in the distribution system they have..215V or 110 V (talking about AC)...it'll be best if you adapt standards applicable to your country...mine, I'm using NEC standards and some of its counterparts...another helpful chart will the chart by OEMs..