Electrical earthing wire (ground wire) used in electrical circuits to enable an electric current to flow back into the ground rather than flowing through the human body that has greater resistance dbandingkan with a grounding wire resistance. For example, if the conductor-voltage contact or stick to the framework of the HVAC units that are not equipped with grounding wire, and then someone accidentally touching the frame.
Then he will be part of the electrical circuit. 1:16 Picture shows the phenomenon. In other words, he will feel the electric shock which can be fatal. Especially if he was barefoot insulated with good.
Pictures 1:16 Typical Electric Current through Hand Shock Victims
Grounding wire installed in an electrical equipment will function as security personnel who will protect personnel from the danger of electric shock. Grounding wire is made such that the resistance value is very low, usually below 5 ohms. Compare resistance of the human body which is in the range of hundreds of ohms. Electric current tends to flow easily into the electrical circuit which has the lowest resistance.
With such a nature, then the existence of the grounding wire will be able to protect personnel from the danger of electrical shock.
Figure 1.17 System Grounding with Grounding Electrodes
In many cases this common grounding wire is green or yellow hijau.Sebuah powered hand tool equipped with a grounding wire, it will be equipped with a plug (plug) which has three contacts, the contacts for the phase wires, neutral wires, and wires for grounding , as shown in Fig 1:18. 1:18 Picture b shows a hand-powered tool that is not equipped with a grounding wire, he only has two contact conductors.
1:18 Picture Tools machine equipped with double insulation