Earth Protection system

In electricity supply systems, an earthing system defines the electrical potential of the conductors relative to that of the Earth's conductive surface. The earthing system has implications for the safety and electromagnetic compatibility of the power supply. Note that there are differences in the regulations for earthing (grounding) systems between England and France.  

A protective earth (PE) connection ensures that all exposed conductive surfaces are at the same electrical potential as the surface of the Earth, to avoid the risk of electrical shock if a person touches a device in which an insulation fault has occurred. It ensures that in the case of an insulation fault (a "short circuit"), a very high current flows, which will trigger an overcurrent protection device (fuse, circuit breaker) that disconnects the power supply.  

TN network (most domestic systems in the UK)

In a TN earthing system, one of the points in the EDF supply transformer is connected with earth, usually the star point in a three-phase system. The body of the electrical device is connected with earth via this earth connection at the transformer. The system is earthed via the outside of the supply cable from the electricty supplier (EDF) back to the transformer. The resistance of the return path is in the region of <1W. (ohms) 

TT network (Most domestic systems in France)

In a TT earthing system, the protective earth connection of the consumer is provided by a local connection to earth (earth rods), independent of any earth connection at the transformer. The systems is earthed via the installed earth rods outside the property which are providing a good connection (a low resistance) to the ground using the general mass of earth as a return path to back to the transformer. The resistance of the return path to pass the regulations is <100W (ohms)

A  lot of people think that installing one earth rod is sufficent, In general this is not the case. The installation of the earth rod/s is quite complicated and you need specailist equipment to measure the reistance of the earth rod, you cannot just use a multimeter from a DIY shop.  

The soil type is a large factor in this measurement and its moisture content. I have heard the story of people pouring water on the earth spike just before the consuel arrive to check it. This may give you the pass you desire but does not necessarily mean that your home and family are safe. It is best to have it inspected and verifed by an electrician with the correct calibrated test equipment. 

This will ensure that the earth point in your property is correct and will provide you with the protection you require all year around.  

If you have any questions with respect to earthing in France feel free to contact me.

For advice and estimates Email: info@electriciansbrittany.com

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