Ahem,
Standard practice has been no Wx Radar, HF transmitting, Strobe lights or engine/APU starting during refuelling.
It is apparently to avoid the chance of any fumes from the fuel tank vents igniting from high energy discharge or jet pipe heat source.
I think the engine/APU exhaust has to be more than 15m from the fuel vent which places the likes of the A330 stab tank vent a bit close to the APU jet pipe.
As I say, all this has been standard practice with my employer for as long as I can remember. Whether or not it is still relevant on a practical day to day operational basis is open for discussion.
