How to safely wire power supply
I don't know all the regulations, especially since you live in a different country than I do, but the general goal is that you don't want a downstream short to be able to melt wires and cause a fire. Using large wires to the converter doesn't solve the problem, you don't know what wire/trace sizes are inside the converter.

So, you want a fuse in your device. You want the wires before the fuse to be large enough to trip the mains breaker without melting if they short. After the fuse, you want the wires large enough so they can withstand the fuse current plus some margin. Use the converter rating and add some margin to determine the fuse rating.

Remember that a fuse rating is the current at which it is guaranteed not to blow, not the current at which it is supposed to blow. The guaranteed to blow value is usually much higher than the fuse rating.

If your device will likely be used by non-technical people, you may want to use a non-replaceable fuse. Otherwise, it is too easy for the user to defeat any safety provisions that you have designed into your device by installing a fuse with a much larger rating.