As our demand for more electricity each year, the demand delivery system increases. This growth makes it necessary, the way our electronic devices are built to change. Fifty years ago the electrical system on our house were built with two drivers. The boss first, called line has been used to provide electricity to our house. The head of a second, called back, was not used to be a possible difference. This potential difference is what causes the passage of electricity and the power of the electronic device.
Today is the manner in which electronic devices use the same stream. The houses are built with a line and a return line, but third driver was added. The third driver, better known as ground equipment known to protect humans and machines, all stray voltage or potential differences. He does this by using the metal frame of an appliance to a grounded outlet near the house. If the electricity produced powers the device should not be energized with electricity by a cable break or short circuit, while electricity would be sent immediately to the ground. This protects the device from damage electrical and people from electric shock.
If you are looking at a modern outlet or exit, you will see three points where the teeth an outlet can be used. The two rectangular openings for line and the legs to the back. Upon closer inspection, find that one of the two rectangular openings slightly smaller. This opening is connected to the power rail and provides power to the circuit. The more rectangular opening is connected to the return conductor of electricity and provides a path to low potential or voltage. Wired correctly is the circular aperture used to ground equipment to connect a unit with the system grounding of the house in connection.
In older homes, it is possible to find containers with only two openings. These openings are for the line and back. The ground equipment is missing. Houses with this type of retail outlet were before the bid, ground equipment are built. They lack the grounding rod and the appropriate cable to insert the image of an electrical device to the heart of the country. To protect people and property against interference voltage must houses without basic equipment some protection installed.