Colonsay electric car charger: don't stand so close to me

This is the electric car charging point at the ferry terminal on Colonsay. I was alarmed to read the notice below:

I have been trying to find out how much current it draws. It's hard to get a definite answer. It could be 32 Amps. It could be 16 Amps. Let's take the higher figure. Magnetic field strength around a cable =mu0*current/2pi*radial distance. Permeability of  free space mu0 is 4pi x 10^-7 Tm/A. So at a radial distance from the cable, magnetic field strength = 32 micro Teslas. Field strength for the Earth's field is about 30 microTeslas. My calculation suggests that less than a millimetre from the cable, the field would be as strong as the Earth. Maybe it is the alternating field that causes the problem, not the overall strength.