For people and equipment protection, it is required to earth the neutral on the distribution network. To know more about the several neutral regimes. The neutral earthing provides protection in the event of default currents on the line. They can occur on many occasions and damage electrical devices and equipment and above all create potential differences, very dangerous phenomena for people.
What is an earth terminal ?
The earth terminal is a system made of several components which, when associated together, enable the default currents runoff in the ground.
Let’s break down the system :
- An overhead connector to tap off the neutral,
- A copper conductor which comes down the pole to link the connector to the earth rod,
- A protective duct to secure the cable alongside the pole,
- A device which enables to open the earth circuit in order to realize resistance measures.
- A junction accessory to connect the earth conductor to the earth electrode,
- An earth electrode, most of the time a rod, to create a contact area with the ground and help the default to run deep in the ground.
How to control the installation efficiency?
By using measure tools as an earth tester, we make sure the installation complies with the required standard when it comes to earth resistance. As long as the targeted value has not be reached, the earth terminal must be improved by linking other electrodes or by going deeper.
Why are we looking for depth when installing an earth terminal ?
The main point of going deep is to get an homogeneous soil and not subjected to climate changes. The resistivity of the ground surface changes with the seasons, phenomenon which disappears in depth. The soil is also wetter. The more the ground is humid the more it conducts electricity and so will be effective at running off default currents.
The earth rod makes it possible to find a stability which guarantees the earth system’s efficiency. Normally its length is comprised between 1 and 2 meters but the rod can be lengthened by means of junction sleeves. We use threaded sleeves for rods with threads and conical nozzle couplings for rods unthreaded.
The accessories required to provide a sustainable earth terminal
in addition to elements listed above, MICHAUD recommends to use accessories to protect cables, to facilitate the installation and the operations…
The installation requires, it will be needed to use the following elements :
- Cable saddles: to guide the conductor while it is running down the pole,
- TPC protective duct: protects the buried conductor in the ground up to the earth rod.
Besides the earth terminal, being in the ground, is subjected to climatic conditions as well as environmental and maintenance constraints which justifies to use:
- Earth pit: provides a dry space for the conductor/rod connection and facilitate operations by making easier the access to the earth terminal in the ground.
- Driving spike and driving end: they facilitate the rod installation and avoid the material degradation. They need to be placed on both ends of the rod.
