The importance of electrical grounding in the property
However, according to NBR 5410, it is a mandatory protection item, as it provides a safe path so that electrical and atmospheric discharges that may occur on site are directed to the ground, in addition to protecting people against electric shocks.
According to IFC/COBRECOM, which is recognized as one of the main manufacturers of electrical wires and cables in the country, if the grounding system is not installed, the people using the property will be unprotected against discharges that may occur during the use of their equipment and household appliances.
Grounding vs. Protection conductor
Professor and engineer Hilton Moreno, who is also a Technical Consultant at IFC/COBRECOM, reveals that it is very important for the project designer to correctly size the grounding system, which includes the protection conductor (popularly called the "ground wire"), which must be present in all receptacle circuits and other electrical energy utilization points in the property, including lighting circuits.
The professional explains that in the grounding system, bare copper cables or wires are generally used, which are in direct contact with the soil, while the protection conductor has the function of diverting leakage currents from the installation components and/or electronic devices to the 'ground'.
"The absence of the grounding system or the protection conductor in each electrical circuit will bring serious risks to people, as this will compromise the safety of the site's electrical installation," emphasizes Moreno.
The Technical Consultant at IFC/COBRECOM also reinforces that in properties without grounding or without the protection conductor in the circuits, people will be unprotected against electrical discharges that may occur during the use of equipment and household appliances, that is, the risks of shocks increase considerably.
Furthermore, every electrical and electronic appliance must leave the factory with means of protection against electric shocks.
Depending on the type of construction adopted by the manufacturer, if it is "class 1", it will be mandatory for the appliance to be equipped with a protection conductor and, consequently, the plugs will be of the three-pin type (phase, phase, ground or phase, neutral, ground).
If the equipment is manufactured according to the so-called "class 2", then the protection conductor cannot be incorporated into the plug, which will therefore have only two pins.
The grounding system, including the protection conductor, is also indispensable to adequately implement an overvoltage protection system for the installation, thus reducing the risks of equipment burning out in the event of atmospheric discharges (lightning). According to NBR 5410, the protection conductor must be identified by the color green or green with yellow stripes.
Sizing
Hilton Moreno explains that grounding is part of the electrical design of a building and must be planned in accordance with the requirements of NBR 5410.
As for the protection conductor, the professional reveals that NBR 5410 determines that it must be sized according to the cross-section of the phase wire, as per the table indicated in the standard.
For phase conductors up to 16 mm², the cross-section of the protection conductor must be the same as the phase wire. For example, if the phase conductor has a nominal cross-section of 2,5 mm² the "ground" must also have 2,5 mm².
In case the phase cables have cross-sections from 25 to 35 mm², the protection conductor will be 16 mm². And, for cross-sections from 50 mm² onwards, the protection conductor will have half the cross-section of the phase conductor.
"It is important to know that the nominal cross-section of the protection conductor is not related to the nominal cross-section of the conductor that comes with the appliance. To size the protection conductor of the electrical installation, it is necessary to analyze a series of factors besides the electrical current that will pass through the circuit. The appliance's protection conductor, on the other hand, may have a smaller nominal cross-section because it only has to solve the internal problems of the household appliance," reveals Moreno.
What to do if the purchased property does not have grounding? According to Hilton Moreno, in this case, a qualified professional should be consulted, such as an engineer, technician, technologist, or trained electrician to indicate the most appropriate way to install a grounding system considering the existing situation on site.
Find a wide category of Overhead Networks at Trifásica Elétrica!
Trifásica Elétrica is a company with over 15 years of market experience in its technical staff, offering solutions for 15 to 36kV lines, among them, a large line of products in the Grounding category, such as bare copper cables, ground rods, clamps, ground inspection boxes, temporary grounding sets, and much more!
Frequently asked questions
Does every property need grounding?+
Yes. NBR 5410 requires grounding in low voltage installations, which is essential for safety.
Do grounding and RCD work together?+
Yes. Grounding allows the RCD to detect current leakage and disconnect the circuit, protecting against shocks.
Trifásica Elétrica distributes medium voltage materials throughout Brazil.
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