An improved surge protection for protecting an electronic device is disclosed, the device having a closed casing with walls made of a non-conducting material and being internally coated with a thin metallic layer. The device also has at least one connector, being arranged in an opening in the walls and including a connector body, at least a portion of which projects outwardly from the wall and which accommodates an internal coupling device, to which a transmission cable, including a central conductor and an outer shield conductor, is connectable. According to the invention, the connector body is also made of a non-conducting material and strong currents, being present at a conducting protection sleeve, are diverted by at least one conducting diversion member to at least one metallic structure, being in permanent electric contact with ground and having a high capacity of conducting strong currents. In use, the at least one conducting diversion member is in electrical contact with the protection sleeve, and extends radially outwardly from the protection sleeve, through the connector body, to the at least one metallic structure.