Thanks so far. Lots to consider. I have several variacs but only one large isolation transformer. I could make another using two transformers or buy another. Would all the equipment on the bench be ok through one isolation transformer? If so I could use my existing one which is capable of supplying 13a at mains voltage.
NO NEVER PLUG YOUR DUT ISOLATOR in your bench tools isolation unit.
Depending on what kind of devices you will work the setup will change.
For tube based devices IDEALLY you would use TUBE based scopes
and meters... kinda proper devices to suit the measures...
You will never use for example an USB scope (5V rated pretty much masx 35V)
with that sort of hardware... got it ? match things is also important.
For SMPS last decade power ranges were more sane.. below 500W is more simple
But present days SMPS have gone insanely dangerous.
Power ratings of 1000W or 1200W are common with AMPERAGE inrush
ratings of 100A or 200A on MOBOs. The kind of ISOLATOR for that is not trivial.
As said above - differential probes are becoming more important.. but nevertheless
they are WAY TOO MUCH EXPENSIVE... unless you make a living of them..
So a couple or 3 ISOLATION UNITS for your bench - ONE SEPARATED UNIT w/a proper
VARIAC for DUTs... - should be a reasonable and affordable setup
.. last but not least - yourself protection pretty much depends on the sort
of work - being solder, HIGH VOLTAGE... and other stuff..
a PROTO BOARD with ARDUINO definitely will not need much...
while DESOLDERING OLD CRAPPY CORRODED AMPS...
will require eye and lungs and skin/nail protection..
NASTY STUFF
Paul