Basically, the ground contact (in the power station) is the earthed neutral conductor. Should a device have a casing which may be conductive, then the ground contact is compulsory and must be connected to the casing. If now, through a possible mishap, the phase comes into contact with the casing, the responsible fuse would prevent an electrical accident. Any person touching the device would thus, remain unharmed.
A further safety-level is provided by the Residual Current operated Circuit Breaker (RCCB), which, for the layman, looks just like another fuse in the fuse-box. Just imagine, you are changing a defective light-bulb and you can't remember the position of the light switch, because e.g., the room has two switches (a two-way-circuit). If current is now laid on and the glas breaks, first of all, 16 Amp. go through your body, whereby, even 50 mA can be fatal.
The RCCB compares the current flow in the individual wires and notices, that something is awry. In as little time as 0,02 to 0,03 sec. It switches the current off. This life-saving device is mostly considered to be annoying, e.g., when you have plugged your hair-dryer into the shaver plug in the hotel bathroom. Indeed, the bathroom was the first room to be protected by the RCCB.
Up to now, the world of mains voltage still seems to be well organised. With the appliance power cord (IEC connector) (up to 70°) shown in the above picture, it starts to get more complicated. The only thing of which one can be certain, is that the No. 2 is the earth. Actually No.1 should be the phase and No. 3 should be the neutral conductor, However, do you know which way the other end of the cord has been plugged in? As we all know, there are two possibilities, making it it very hard to standardize. 08/11
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