"Dave Plowman (Nutcase TROL)"

In the world of live music, I have come mixed class I / II systems that
are very scary.

In UK TV studios etc, before the days of RCDs etc, every single item of
unknown equipment - like say a guitar amp etc supplied by a musician - was
fed via a mains isolation transformer. Expensive and time consuming but
very necessary.

** Really ????

Bet the Beeb et alia stopped doing that when they nearly electrocuted the
first guitarist.

1. The most common error in AC plug wiring is Neutral-Earth reverse - the
item works and there is no big problem until you find an AC outlet that has
Active and Neutral reversed.

2. Add a 240:240V iso-transformer that carries the supply ground through to
the outlet and it becomes instantly lethal. Draw it out on paper if you
doubt me.

FYI:

Supply earth goes direct to one side of the amp's AC tranny, then the
iso-tranny's 240V winding and back to the amp's chassis. The amp will not
run - but the chassis is 240AC live.

Oooouuucchhhhhh !!!!!!!!..



..... Phil