Well, your use of the word "allowed" led me to believe that you were more concerned that your appliances were going to be confiscated if you took them to the uni and tried to use them.
Anyway, no, it's not the case. If it was, the fridges and microwaves in the kitchens wouldn't work either!
Either they're just trying to keep their leccy costs down, or minimise the chances of someone bringing something that IS a faulty high-voltage product that will trip electricity.
As long as your stuff is safe I.e. not ancient and not damaged it will be fine. I was using hair straighteners, hair driers, some of my flatmates had huge amps etc. it won't be a problem.
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