Arfa Daily wrote:

(some content snipped)
I've never been a great believer in the appropriateness of applying
these tests to double insulated and transformer based equipment,
particularly given that large DC spikes are applied, which with some
testers are actually twice the nominal line voltage. Given that in much
microcontroller based electronic equipment, digital grounds are not
directly bonded to other system grounds, it seems to me that having big
voltage spikes flashing around between the primary side of the power
supply, and cabinet metalwork, which is not grounded to any line power
earth, but may well be AC common to internal DC grounds via low puff (
and sometimes not-so-low ) caps and high value resistors, is asking for
trouble of the same nature as you might expect from static damage, or
pulse damage from nearby lightning strikes.

I would be interested in knowing if I'm on my own on this one, or if
anybody else involved professionally in service work - or indeed anyone
who carries out PAT testing - has any similar experience, or opinions on
this.

Arfa

I had to look up "PAT Testing" online. It sounds like yet one more
unnecessary time-and-money-wasting government annoyance, like lead-free
solder and banned cleaning solvents. I'm sure we in the USA will be
doing that too, soon enough. At first glance, an incorrectly applied PAT
sounds like a fine way to destroy MOV protection devices.