Protective contact
A protective contact is a connector contact intended for the protective conductor (PE) . Together with the use of at least a three-wire connection cable, it enables movable electrical devices to be connected to a protective conductor.
Housings of stationary installed devices (e.g. stove, boiler , washing machine) can be grounded by a separate, permanently installed protective conductor. In the case of movable devices that are not secured by other suitable protective measures such as protective insulation , the protective conductor must also be carried along in the connection line in addition to the power supply, which therefore has at least three wires.
The protective earthing of such devices is carried out by connecting the cable to a corresponding socket which, in addition to the sockets for the outer conductor and neutral conductor, also contains a contact or socket that is connected to the protective conductor.
If the connection of a metallic device housing intended for protective earthing is interrupted at any point, the protection is no longer given. This is also the case if no protective conductor is connected to the socket or a mains connection cable without a protective conductor is used.
In the past, the protective contact was often zeroed without a protective conductor ( classic zeroing ). This is no longer permitted for renovations and new buildings in German-speaking countries.
Examples of plug systems with protective contact are:
- Schuko (abbreviation for protective contact)
- Perilex (obsolete)
- CEE three-phase connector
- IEC-60906-1 flat plug
Features of protective contacts are:
- leading, that is, it connects first when plugging in and disconnects last when loosening
- Current carrying capacity at least like the other connector poles
- Contact protection not required
See also
- Country overview Plug types, mains voltages and frequencies : single-phase (typical household) plug connector types used worldwide
literature
- Günter Springer: Expertise in electrical engineering. 18th edition, Verlag Europa-Lehrmittel, Wuppertal 1989, ISBN 3-8085-3018-9 .