I've never blown a fuse in the UK from a SMPSU under normal operation. You're either using fake fuses or something was wrong with your power supply. Look at the fuse curves for a BS1361 fuse!
The fuses were supplied by the hotel and did not blow when using the kettle which, needless to say, used a lot more power than the laptop. The PSU is SONY original and works just fine except for that inrush current which I take it comes from having a rectifier bridge followed by a large capacitor. I installed the NTC and that solved the problem. The problem is therefore solved and needs no further resolving.
Getting back to the issue of safety, I have been doing some reading and some learning and it is a fascinating topic although quite complicated. There are categories by types of users, voltages, accessibility, etc. But, to simplify a lot, let us restrict ourselves to devices at mains voltage to be used by ordinary persons.
For example an old hand-held electric drill with metal exterior housing. If the enameled wire in the rotor were to fail it could make contact with the core which would make the external housing live through the shaft and bearings. The insulation provided by the enamel is weak, "basic insulation". So this device would not be authorized for sale today.
To make it safer we cannot increase the enamel thickness and insulation to needed levels but the code authorizes us to ground the external housing so that if there is a fault, an "abnormal condition", the user is protected and the current would be diverted to ground by a path other than the user's mortal body. Class I.
Now, the manufacturer can add a second layer of insulation, "supplementary insulation" between the core of the rotor and the shaft so they are electrically insulated from each other. If the basic and supplementary insulations added up meet the specs as to dielectric rigidity, clearance, temperature, accessibility by the user, etc. then that classifies as class II and grounding is not required but in no way is it forbidden. Grounding the external case can be kept or added and, in fact, always adds safety.
Note that "class" refers to each conductive (metallic) part individually. When referring to a device it would be the lowest class of any part that can be touched by the user. And "can be touched" also requires defining apertures and dimensions of holes where a user could put his pinky (I mean his little finger).
Also note that insulation class is a general analysis of electrical conditions of metallic parts and how they could fail electrically. A metal workbench in a shop, not connected to anything electrical, is already class II because it surpasses all the dielectric and other requirements. That spoon you use for soup? Class II.
But grounding that metal bench still adds safety. Maybe one day some wire touches it and the user would be protected.
By the way, the regulations assume the common user is always grounded and
will get a shock if in contact with any live part. If the user needs to be insulated he is no longer an "ordinary user".
If you look at the PCB of a SMPS you can see cut-outs in the PCB between the mains side and the output side. This is because the safe dielectric distance (clearance) is much lower in open air than over the surface of the PCB (creepage) which can cause flash-over if dirt accumulates. Varnishing the PCB can also reduce creepage distance.
I am getting a pretty good understanding of all this protection business and yet a question comes up in my mind. A SMPS PCB has cutouts so it can maintain certain open air distance between primary side and output side. And yet the Y capacitor is mounted (IIRC) in two holes and pads very close to each other and which would not meet dielectric requirements. Not to mention the capacitor itself. If this arrangement does not meet the requirements for "reinforced" insulation, it could well be the PSU does not meet Class II specs and should, in fact, have the output side grounded.
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