Cited are things totally irrelevant to the OP. Why discuss
"unfused plug adaptors" when there are none? Why even raise
this totally irrelevant issue? Apparently all power cords had
13 amp fuses or equivalent protection. Apparently his loads
were so small as to not even blow those 13 amp fuses.

However what is the expression I keep posting multiple times
in every post? 15 amp circuit breaker on every power strip.
Why are we now discussion a green moon - also known as
"unfused plug adaptors"? Please return to the relevant
topic. Please tell the OP why overloading caused damage to
multiple computers and a printer.

I would not be surprised if someone threw in a discussion of
a refrigerator connected to a defective wall outlet. Why
would speculated and unsubstantiated overloading (that also
could not blow line fuses) cause damage to multiple computers
and a printer?

James Sweet wrote:
What about all the 15A outlets on 20A circuits? It's quite common
in the US anyway, to have a number of 15A outlets on a 20A branch.
It's fully possible to overload the outlet with unfused plug
adapters, lots of those out there. The circuit breakers on power
strips aren't of the highest quality either.