Grounding by the rules: the main thing you need to know

  • Dec 14, 2020

A high-quality and reliable ground loop is the key to safe operation of household electrical appliances and all electrical wiring in general. But in order to properly carry out the installation of grounding, it is necessary to refer to some regulatory documents, namely - See section 1.7 of the PUE.

What can be used as ground electrodes

Temporarily postponing the topic of the construction of the grounding loop, it is necessary to deal with the material that will be required for the work. This is the main question before installation: what can be used as ground electrodes?

Clause 1.7.109 states that both ready-made materials (natural) and artificial (created separately after the construction of the building) can be used as a protective circuit. The first type includes structures of structures, water pipes and even rail tracks, and the second - a circuit that was laid independently after the completion of construction.

What should be the grounding conductors (paragraph 1.7.111):

  • Made of copper, black or galvanized steel.
  • Clean, without primer or paint.
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To determine the diameter and cross-sectional area, depending on the material, you should use a convenient and easy-to-understand table from the same section 1.7:

Table: Dimensions of grounding conductors and grounding conductors

Cross-section of grounding conductors

In the subclause "Grounding conductors" of section 1.7 there are references to table 1.7.5, in which the cross-sections of the grounding wires are determined based on the phase conductors. In paragraph 1.7.117 the cross-section of the conductor connecting the ground loop and the main bus is indicated separately:

  • Copper conductor - cross section not less than 10 mm2.
  • Aluminum conductor - cross section not less than 16 mm2.
  • Steel conductor (practically not used in modern electrical networks) - cross section not less than 75 mm2.
Figure 1: Place of connection of the earthing switch to the main bus
Necessarily! Where the grounding wire is introduced into the building, an appropriate sign must be installed.
Figure 2: Grounding sign

The cross-section of the grounding conductors laid in the section from the bus to the consumers is determined by simple formulas:

  • If the cross-section of the phase conductor is S≤16, then the protective cross-section: S.
  • If the cross section of the phase conductor is 16
  • If the cross-section of the phase conductor is S> 35, then the protective cross-section is S / 2.

Of course, these instructions of the PUE are practically not followed, since the costs of installing protective conductors throughout an apartment or a private house will, to put it mildly, costly. Consumers prefer to lay a protective wire of the same cross-section as the phase wire with zero.

What design to choose a ground loop

The ground loop in the form of a triangle is the last century. The main advantage of this design is the ability to install it with your own hands. Many electricians prefer to install pin-type ground loops. Installation of such a ground electrode system takes a minimum of time, effort and has a long service life. All you need is a grounding rod kit, a hammer drill and a special attachment. Installation time: no more than one hour.

Figure 3: Delta ground loop