Grounding systems Ground and neutral

the iec standard (iec 60364) codifies methods of installing neutral , ground conductors in building, these earthing systems designated letter symbols. letter symbols common in countries using iec standards, north american practices refer iec symbols. differences conductors may separate on entire run equipment earth ground, or may combined on or part of length. different systems used minimize voltage difference between neutral , local earth ground. current flowing in grounding conductor produce voltage drop along conductor, , grounding systems seek ensure voltage not reach unsafe levels.

in tn-s system, separate neutral , protective earth conductors installed between equipment , source of supply (generator or electric utility transformer). normal circuit currents flow in neutral, , protective earth conductor bonds equipment cases earth intercept leakage current due insulation failure. neutral conductor connected earth @ building point of supply, no common path ground exists circuit current , protective conductor.

in tn-c system, common conductor provides both neutral , protective grounding. neutral conductor connected earth ground @ point of supply, , equipment cases connected neutral. danger exists broken neutral connection allow equipment cases rise dangerous voltage if leakage or insulation fault exists in equipment. can mitigated special cables cost higher.

in tn-c-s system, each piece of electrical equipment has both protective ground connection case, , neutral connection. these brought common point in building system, , common connection made point source of supply , earth.

in tt system, no lengthy common protective ground conductor used, instead each article of electrical equipment (or building distribution system) has own connection earth ground.

as per indian cear , rule 41, grounding system follow:

- neutral conductor of 3-phase, 4-wire system , middle conductor of 2- phase, 3-wire system have minimum 2 separate , distinct earth connections minimum of 2 different earth electrodes have earth resistance satisfactory value.

- earth electrodes inter-connected reduce earth resistance.

- neutral conductor shall earthed @ 1 or more points along distribution system or service line in addition connection @ user end.