Flat right-angle plugs with a protective-earth contact are used to connect electrical devices to fixed sockets located behind furniture or other obstacles in building wiring systems. When using the flat plugs, the amount by which the plug protrudes from the fixed socket should be minimised. These plugs have a lower overall height than the classic right-angle plug.

Technical specification for flat right-angle plugs with a protective-earth contact

Depending on their design, specifically the geometric shape of the housing, flat right-angle plugs with a protective-earth contact may not be able to be fully inserted into the fixed socket. This partial insertion position and the lateral/oblique pressure on the contacts of the fixed socket pose safety risks and could potentially cause long-term damage to the contacts without anyone realising. Furthermore, as a result of pulling (even inadvertently or accidentally) on the plug cable, certain types of flat right-angle plugs with a protective-earth contact can assume partial insertion positions, which can cause an arcing fault. The fixed socket is not designed for the thermal stress caused by partial insertion and, if it is exposed to additional stress, it is at risk of catching fire, at least in the long term. Likewise, the contacts in the fixed socket may be bent; this reduces the contact pressure and causes the contacts to heat up so much under high loads (power consumption) that they catch fire.