Earth-Continuity Conductor

3 core cable

In every electrical installation, unless it has no metal in it other than the current carrying conductors, has an earth-continuity conductor in it which is electrically continuous through out the installation. This is a cable or any other conductor, which is connected together all metal parts of an electrical installation. e.g switch fuses, fuse distribution board, steel conduit, metal frame work on which electrical apparatus is mounted. The earth continuity conductor is connected to earthing lead at a connecting point.
In a metal conduit system the conduit itself may act as a earth continuity conductor. It may be meta sheathing of cables or special continuity wire enclosed in the cable sheath. In  the case of portable appliances the third end larger pin of the plug socket outlets is used for this purpose. When the metal sheathing of cables or metal conduit is used as an earth-continuity conductor then all joints should be tight and bonded together and be protected where necessary against corrosion.
According to I.E.E.E regulation, the following shall be connected to the earth-continuity conductor, the earthing terminal provided at every lighting point and exposed metal parts of the apparatus.
The (e.c.c) shall be connected to jointed point. This bonding or jointing point must be in and this accessible point accessible point can be anywhere?
I.E.E regulation (E3) require that where earth-leakage protection relies on the operation of fuses or excess current circuit earthing terminal and the remote end of every (e.c.c) shall not exceed one ohm (1 ohm). When (e.c.c) is bonded to casing of apparatus, it should be tightly clamped by the special screw provided on the casing. In  Pakistan the electrical apparatus (e.f motors transformers, generators, machinery using, electrical power apparatus used for regulating or controlling electrical energy and all medium voltage apparatus) must be earthed by the two  separate to connections with earth. The both two earth leads are not joined to one earth electrode, while separately jointed two earth electrodes. The distance between two earth electrodes is 5 ohms to 8 ohms. Remember that, where the (e.c.c) is connected in a flexible cable or cord it should have a cross-sectional area equal to the largest current-carrying conductor of that cable or cord. Every (e.c.c) which is not contained in a composite or flexible cable must me insulated by the color green or yellow. Where the sheath of a composite cable is removed adjacent to joints, the (e.c.c) must be insulated. The resistance of the consumer's (e.c.c) should not exceed (1 ohm).