According to AS3008, under the same condition where 2.5 mm^2 is good for 20 A, 8 AWG (8.3 mm^2) is only good for 40 A. Those conditions include 75°C rated insulation and 3-core flat in conduit in air.Faz wrote:Good in theory but in reality any resistance in the connection of the cable to the outlet makes the 20A capability of the cable meaningless.
I have a solar battery charger limited to 30A. I recently noticed charring on the insulation of an 8AWG cable where it enters a brass distribution bar. The cable is over 7mm^2 and is rated for 60A yet gets noticeable warm carrying less than 30A.
The only way 8 AWG cable could be rated for 60 A is if it has 110°C rated insulation. In which case you are only getting the higher rating because the insulation can take a higher temperature and so it _will_ run noticeably warm.
Let me guess. This 8 AWG 110°C cable is flexible. i.e. it has many fine strands. And it has been clamped under a screw in a brass distribution bar without first putting it in a ferrule?
Even if there is a high-R connection at the GPO, a 10 A load from an EV on a 10 A GPO is not going to overheat the 20 A cable in the wall cavity, apart from the few millimetres near the GPO. The GPO or plug will soften and droop or (as you mention) char, long before any fire occurs. If a person keeps using a GPO showing signs like that, and doesn't get it checked, ...The length of time involved in charging an EV increases the chance of a heavily loaded cable getting hot enough to start a fire.