Partner has a MacBook Air. And the other evening she realised that if yo= u =
ever-so-gently brush your hand across the case, there is a sort of very = =
mild electric tingle. Although it varied in strength a bit, it did seem = to =
be present wherever you touch the case, with it folded up or open, on th= e =
inside around the screen or keyboard, anywhere.
A bit of surfing later found that this is a widespread phenomenon across= =
many metal-clad lappies of various makes. Eventually even found a soluti= on =
posted =E2=80=93 use the long mains lead. (For those who, like me, don=E2= =80=99t have a =
Mac, their power supplies have the choice of a slide in duckhead which =
allows the lump to plug straight into a 13A socket. Or a longer cable =E2= =80=93 =
more like a kettle lead =E2=80=93 which allows the lump to be a metre or= two away =
from the 13A socket.)
Sceptical, I could not think why that would work and assumed it was =
mis-guided advice. Until tried. It worked. The tingle dropped away to th= e =
level where you are not sure if it has totally disappeared or not.
The longer mains lead is also made of a peculiar material =E2=80=93 it l= ooks like =
normal flex but is strangely less flexible and doesn=E2=80=99t even feel= like =
normal PVC outer insulation. In some ways it is a bit like some car HT =
leads! So I start thinking that this special lead has some magic =
properties that somehow dissipate whatever is causing the tingle.
Partner then tried a much older lead =E2=80=93 and this was most definit= ely like =
any other mains flex. So I was surprised when that too reduced the tingl= e =
to nothing.
Trying the same on a MacBook Pro had exactly the same effect =E2=80=93 e= xcept that =
the tingle was much less noticeable in the first place.
So, to the questions. What causes the tingle and why does using the long= =
mains lead stop it happening? And why is the new mains lead so peculiar?=