How many ground electrodes do we need?

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31.07.14                   , , , , , 

When choosing the configuration of a grounding device we often ask ourselves how many grounding electrodes we might need. Should we mount modular grounding with one or three points?

modular grounding with one points

modular grounding with three points

Let's consider ZZ-000-015.

The kit includes:

3 наконечника и 3 зажима указывают на то, что данный комплект может быть смонтирован в виде "трёх точек". В данном случае электроды могут быть следующих длин: 4,5 м + 4,5 м + 6 м. Но есть возможность смонтировать и "одной точкой", глубиной 15 метров.

3 tips and 3 clamps show that the kit can be assembled in a "three-point" manner. In this case the electrodes may be 4.5 m +  4.5 m +  6 m long, but it is possible to mount in the "one point" manner with 15 m depth.

What should you choose and why?

There are different recommendations for different grounding purposes:

  1. For the grounding of the lightning protection with the required quality (grounding resistance) we recommend a multi-purpose kit for modular grounding ZZ-000-015 assembled as electrodes placed 5-10 meters from one another. 
  2. For grounding of a pipeline / gas boiler with the required quality (grounding resistance) we recommend to use a multi-purpose set of modular grounding ZZ-000-015 assembled as one electrode (point grounding).

For standard protection of electrical equipment, you can use both single-electrode and three-electrode configuration.

Air temperature in the region is an important value as well. For example, in the northern regions of the country, where winter reigns nearly all year round, the soil is frozen and its resistivity is many times as large as that of the soil in the Moscow region. However, in the cold season even in Moscow and other warm regions the soil freezes to 1-1.5 meters, which evidently increases the resistance.

It is evident that in case of the single-point mounting the electrode is less exposed to cold as compared to the three-point mounting

Single-electrode mounting:

Single-electrode mounting

Freezing level

Three-electrode mounting:

Three-electrode mounting

Freezing level

Notwithstanding, the depth and quality of the material ensure considerable resistance even in the cold season.

The soil type can also influence the configuration. So, it can be hard to install a 15-m deep electrode in rocky and high density soils, even with the help of a hammer drill. But fortunately, ZZ-000-015 set  includes the components for the 3-electrode configuration.

In all-year winter regions, it is recommended to use an electrolytic grounding system.

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