Is this dangerous for just a couple of days? Im inclined to think so. Both of the extension leads are surge protected. Ive found the space of my new fish tank and have a 2m surge protected lead, but its about 50cm too short, but I want to start the pumps etc tonight as I am collecting live rock on saturday so I want the water to be heated and the salt etc mixed in. So I wanted to use another surge protected lead to extend the tank lead. Theres 4 plugs that will be running from the tank (for the time being).