- 1 April 2020
- Posted by: Forend Forend
- Category: Grounding
Foundation of Grounding
Foundation grounding is one of the most important grounding methods known ever. Foundation grounding of buildings must be started at the beginning of construction (at foundation stage). This is performed by laying a galvanized conductor between reinforcing bars. This conductor is connected to reinforcing bars at certain distances. The ends of this conductor are taken out from some specified points and left as the “connection bud”. Once these buds are connected to the equipotential grounding bus bars, the grounding is completed by connecting all systems to be grounded to these buses. Foundation grounding (embedded conductor) must be designed in the form of a closed ring, and placed in the foundation of the external walls of the building, or the foundation platform. Connection must be established with reinforcing bars every few meters.
Measurement of Ground Resistivity
In order to measure the ground resistivity to predetermine the ground dispersion resistance or grounding impedance, the “Four Probe Method” (e.g. Wenner Method), which enables determination of this resistance for various depths, must be used.
Regulation Annex-N 2.2.1 can be referred to for the distances between probes. Special devices have been designed to implement this method.
The safest system in grounding is the equipotential system. In this system all groundings and metal sections are connected to each other by means of equipotential bus bars. The voltage difference that might occur at any two points in the installationis prevented, and equipotential is provided at all points. While connecting the lightning protection system with the equipotential system it is required to take precautions against overvoltages that might occur. For this purpose, an “internal lightning conductor” (overvoltage impact protection) must be included in this system. Otherwise, electric-electronic systems and equipment are at great risk. While connecting different grounding to each other, the connection must be established through the potential equalizers.