Just buy from a reputable supplier. Items like plugs are self-certified - there is no third-party testing. Get a branded plug, not Chinese one. It's amazing how many plugs I have that are marked CE or BS that do not comply with the regs. I have a credit-card sized template that checks if the pins are the right size and if the top is large enough to keep fingers away from live parts.
If it's rated at 13A that's it. The rating is not limited to one hour! At 13A the fuse will get hot but it will have reached its max temperature within the hour.
If it's rated at 13A that's it. The rating is not limited to one hour! At 13A the fuse will get hot but it will have reached its max temperature within the hour.