John Robertson wrote:



As long as the variac passes basic eletrical leakage test fine and the
powre cord and internal wiring are in good condition there is little
sense in trying to upgrade it to three conductor wiring.


** To maintain the safety of equipment that normally uses a ground conductor with a 3 pin plug - earth continuity must remain intact.


In fact I recall reading somewhere (can't find the link) that it is
against the electrical safety regulations to convert two conductor
products to three conductor.


** If the product as originally sold was of Double Insulated (aka class2) design, this may be true. Earthing a Class 2 shaver is silly.

But I would not hesitate to add a 3 conductor cable to any guitar amp, powered desk or similar I found that did not have it.


This could be incorrect, until I can find
the reference take it with a grain of salt. However many items wired for
two conductor would need to be modified for three conductor beyond just
adding a ground - in pinball and jukeboxes the older two conductor items
correctly had the power switch on one side of the line and the line fuse
on the other - this is totally wrong on three wire setups!


** Sounds easy enough to correct, as it is to remove the infamous "death cap" fitted to many 2 wire guitar amps not so long ago.



..... Phil