You're not going to get any plug in non-linear loads without suitable PF correction fitted within. Even still, any negative effects caused by slight inductance or capacitance will be negligable.
So you are categorically stating that if 2 off 20A single phase loads were plugged into 2 separate single phase circuits they could NEVER overload the 2.5mm sq N conductor?
Thing is you don't know what is going to be plugged in.