Re: C'mon, Dr. S, this kind of trolling is beneath you.
If any part of the external chassis is "hot", for any reason, there is a flaw in either the design or the implementation.
Not necessarily hot but definitely giving a tingle that shouldn't have been there, hence the extra insulation. Having a satisfactory solution - and enough other problems - we never investigated further but put it down to insulation good enough for US mains not being good enough for UK.
In elfin safety terms in that lab it was relatively minor. One research student nearly burned down the lab twice. SMBO made analar meringues - at least the sucrose was analar - in the same oven we used in the open lab for evaporating benzene off of samples. Another drying oven ended up with no fan blades: the HCl content of what was being dried had eroded them. And it took me years to realise why one sink had always leaked: the HF that was sometimes disposed of in it had dissolved the glaze.