Please don't do the 'training on these topics', 'pretend to be authoritative' thing. I have designed industrial stuff for a living, have you?
I follow the standards, they're a collection of knowledge spanning far more than my experience..... which includes electrical apprenticeship and designing (
A brand) test and measurement equipment (to 61010).
In countries that have no plug fuse (and that's the only UK reference I'm going to make) [Edit: the appliance lead] must be rated to handle the full final circuit breaker current in fault situations.
No, they don't. Please do provide a reference for that, because the references I have here (61010, 60335 , 62368, etc) certainly do not require appliance leads to support either the prospective fault current or even the maximum permissible hold current of an arbitrary power point/socket outlet. 0.75mm2 cables terminated with C13 plugs are pretty typical, around the office here they are the majority, and have test approvals and in service test tags that are current.
No clever arguments.
None? Why try and redefine the boundaries of CAT II, CAT III, and CAT IV ? Then dig in and make all sort of noise about things you clearly know very little about? Safety isn't the place to try and find loopholes, or muddy the water with your plainly incorrect misleading and heading into dangerous claims.
CAT III includes the wall mounted socket outlet, that's what 61010 defines. It's like trying to argue about the arbitrary steps in EMC regulations, 229MHz emissions affects things almost the same as 231MHz.... except 55011/55022/etc standards have 230MHz as a boundary between different requirements so they are treated differently. There may only be a slight distinction in reality between either side of a socket outlet in worst case conditions, yet there is a significant difference in most conditions. The line between different categories has to be drawn somewhere and the boundary of fixed wiring is easily recognisable, I think that is a pretty good place for the distinction.
For the dear love of Jesus, this was a thread about ANGENG SZ20, that is now covered in sterile, off-topic discussions of bloody fuses , obscuring anything about the poor multimeter.
.. and the OP asking why CAT ratings are required, apparently without realising where those ratings are applicable.