I'm sure its against forum policy to advise bad practice so I wont go into detail, however in the uk standards are such that you cannot override a circuit breaker by fastening it up.
0.5A is hardly anything, you'll really need to be carefull what you plug in, I have a narrow boat that has a 12v battery and power system I have to be carefull about what I use, there is mains ac power but thats only present with the engine running, I have to have a checklist of things to charge up when the engines running.