19 Nov, 2021

How Type A Earthing Is Different From Type B Earthing in Lightning Protection System?

Which Is Recommended By The Standards? 

Concrete Built-In Foundation Earth Electrode OR Ring Earth (Type “B” Earth Connection According To IS / IEC 62305)
V / S Floor Embedded Earth Electrode (Type “A” Earth Connection According To IS / IEC 62305

The concrete used for the foundations of buildings has a certain conductivity (relative comparison) and, in general, "a large contact area" with the ground. It is highly recommended to use bare metal electrodes completely embedded in concrete (to a minimum depth of 5 cm) for grounding purposes, as they are highly protected against corrosion, usually for the entire life of the building according to IEC 60364: Installations Low Voltage Electrical, Part 5-54: Selection and Mounting of Electrical Equipment - "Grounding Arrangements and Protective Conductors" also known as earthing system. It is recommended that the conductive effects of building reinforcement be used as well, whenever possible, but the goal should be to use it rather than abandon it.

The "only economical solution" is to use a foundation earth electrode embedded in concrete during the construction of the building (itself) to obtain a lower earth resistance value that is long-standing because:

1. Does not require additional excavation work.

2. It is erected at a depth that is normally free from negative influences resulting from seasonal weather conditions.

3. Provides good contact with the ground.

4. It extends over virtually the entire surface of the building foundation and results in minimum ground electrode impedance that can best be achieved with this surface.

5. It also provides an optimal grounding arrangement for the lightning protection system.

6. From the beginning of the construction of the building, it can be used as a ground electrode for the electrical installation of the construction site, resulting in great savings, as we can completely eliminate the temporary ground electrodes.

7. Provides a good foundation for the main protective junction as the junction takes precedence over the ground itself by standards.

Only in the event that the foundation has to use certain insulating measures against water, the following alternative measures shall be used:

- For grounding, an additional concrete embedded foundation earth electrode will be used below the ISOLATED FOUNDATION.

- A grounding arrangement will be used around the building. GROUNDING RING.

-Finally, if the above options are not possible in practice, type A ground rods will be used as the last option.

Lastly, single foundation concrete embedded foundation earth electrodes (e.g. a large room) should be connected to other parts of concrete embedded foundation earth electrodes by using suitable earth conductors to meet the “GLOBAL GROUNDING CONCEPT” as described in IS 3043 - Code of practice for grounding.

Only the stainless steel electrode should be installed directly from the foundation concrete to the ground to avoid corrosion effects. Hot dip galvanized steel should not be used for this purpose.

After preparing the connected reinforcement, but prior to pouring the concrete, an inspection record and documentation of the arrangement should be made by a trained person, containing the description, drawings and photos, and should be part of all installation documentation electrical.