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The TT (French: terre–terre) earthing system. In a TT (Latin: terra–terra) earthing system, the protective earth connection for the consumer is provided by a local earth electrode, (sometimes referred to as the terra firma connection) and there is another independently installed at the generator. There is no 'earth wire' between the two.
An isolated ground (IG) (or Functional Earth (FE) in European literature) is a ground connection to a local earth electrode from equipment where the main supply uses a different earthing arrangement, one of the common earthing arrangements used with domestic mains supplies.
These are all brought back to some common point in the building system, and a common connection is then made from that point back to the source of supply and to the earth. In a TT system, no lengthy common protective ground conductor is used, instead each article of electrical equipment (or building distribution system) has its own connection ...
In electric power distribution systems, a protective earth (PE) conductor is an essential part of the safety provided by the earthing system. Connection to ground also limits the build-up of static electricity when handling flammable products or electrostatic-sensitive devices.
The purpose of connecting the customer's system to ground is to limit the voltage that may develop if high voltage conductors fall down onto lower-voltage conductors which are usually mounted lower to the ground, or if a failure occurs within a distribution transformer. Earthing systems can be TT, TN-S, TN-C-S or TN-C.
Electrical equipment may be designed with a floating ground for one of several reasons. One is safety. For example, a low-voltage DC power supply, such as a mobile phone charger, is connected to the mains through a transformer of one type or another, and there is no direct electrical connection between the current return path on the low-voltage side and physical ground (earth).
This page was last edited on 30 July 2005, at 20:48 (UTC).; Text is available under the Creative Commons Attribution-ShareAlike 4.0 License; additional terms may ...
Earth-return telegraph is the system whereby the return path for the electric current of a telegraph circuit is provided by connection to the earth through an earth electrode. Using earth return saves a great deal of money on installation costs since it halves the amount of wire that is required, with a corresponding saving on the labour ...