You always can recognise the phase line by using a "phase-meter" or "live-meter" screw driver. You can buy that some 50 cents. Push it into one of the holes while your thumb is attached to the other end of the screw driver. If that hole is live the "neon lamp" in the screw driver upper body turns on in orange color. Otherwise, it remains off. Neon lamp has electrical resistance to reduceYou always can recognise the phase line by using a "phase-meter" or "live-meter" screw driver. You can buy that some 50 cents. Push it into one of the holes while your thumb is attached to the other end of the screw driver. If that hole is live the "neon lamp" in the screw driver upper body turns on in orange colour. Otherwise, it remains off. Neon lamp has electrical resistance to reduce the live voltage to a safe vale at the other end that you have attached your thumb. Your thumb works as a null for the lamp. In Britain, socket holes do not open to allow inserting that phase-meter to check if a socket is functioning at all or not. They have something like a British plug with a lamp on its outer body that by insertion turns on. (in Italy) if you are a bit myth buster person, push that screw driver in the live (phase) hole and attach the back of your palm -I repeat the back of the palm, not the palm- to a radiator pipe or a metallic tap cautiously. By pressing further you get to a point that you feel the shock. Then make your hand separate. (You are using the back of your palm in case the electricity clinch your fingers then your hand becomes automatically separated from the point of contact.) Now you understand why for the electrical appliance there is no difference between Phase and null. The poor appliance is firmly attach in one side to the null (say to the tap). Null is safe as far as there is no phase on the other connector. Experienced electricians who have to work with live electricity, recognise the live with phase meter, red tape the naked lives and wear safety shoes to insulate them from the ground. For high voltage overhead lines they have to go into <PERSON> cages to be separate from Zero- potential. 71
Then like birds who safely sit on power-lines they can work with 400000 volts live lines. Perhaps you saw that <PERSON> could escape from prison by jumping and sliding on one of these lines (I wonder on the other side how could he come to the ground!) There are situations that you cannot work symmetrical with phase and null. For example you cannot put your switch on the way of a null line. It becomes dangerous, or in some cases like a door bell you frequently receive spontaneous ringing (phase always might find a null around and turns on the appliance). In Italy if you plug the fridge or the kettle in the other way, then by touching (with the back of your hand) the body of the appliance you feel a very faint feeling of the shock. Then immediately correct the plugging into the reverse of the previous connection. VDE now has become the backbone of EU electrical regulations that makes a new safer standard for southern European countries compulsory. When working with live electricity you must have a peer buddy around. You also should put on safety goggles and safety shoes and gloves. You also might like to read chapter nine of <PERSON>'s Lectures on Electricity and Magnetism or <PERSON>-<PERSON> chapters on this subject. the live voltage to a safe vale at the other end that you have attached your thumb. Your thumb works as a null for the lamp. In Britain, socket holes do not open to allow inserting that phase-meter to check if a socket is functioning at all or not. They have something like a British plug with a lamp on its outer body that by insertion turns on. (in <PERSON>) if you are a bit mythbuster person, push that screw driver in the live (phase) hole and attach the back of your palm -I repeat the back of the palm, not the palm- to a radiator pipe or a metalic tap cautiousely. By pressing further you get to a point that you feel the shock. Then make your hand separate. (You are using the back of your palm in case the electricity clinch your fingers then your hand becomes automatically separated from the point of contact.) Now you understand why for the electrical appliance there is no difference between Phase and null. The poor appliance is firmly attach in one side to the null (say to the tap). Null is safe as far as there is no phase on the other connector. Experienced electricians who have to work with live electricity, recognise the live with phase meter, red tape the naked lives and wear safety shoes to insulate them from the ground. For high voltage overhead lines they have to go into <PERSON> cages to be separate from Zero- potential. 71