Reliable insulation of electrical appliances is an important component of electrical safety. However, no matter how reliable isolation is, you cannot rely on it completely. Overvoltages occurring in the electrical network for various reasons lead to damage of insulation, which carries a direct threat to human life.
Grounding of household appliances
Grounding is used to protect against electric shock. It is possible to achieve electrical safety by using grounding devices consisting of ground electrodes and grounding conductors. Grounding can be used in networks designed for any voltage.
Many people consider grounding of household appliances in an apartment as an unnecessary precaution. However, the number of household electric trauma associated with the operation of equipment with damaged insulation indicates the opposite. Most accidents are caused by simultaneous contact of the damaged insulation of the household appliance and the conductive object. In residential buildings, radiators and central heating pipes, metal sinks and ungrounded cookers most frequently act as such items.
Figure № 1. Electrical equipment in the house
Which household appliances need to be grounded in the house
Most part of home electrical equipment is a source of increased danger of electric shock in everyday life. To completely eliminate possible risks, it is necessary to ground washing machines, electric and induction cookers, microwave ovens, personal computers, boilers. The safety of boilers should be given the utmost attention. Water is the best conductor of electricity. Damane in the boiler's insulation will lead to the fact that, touching the water heater a person will get an electric shock. The mounted grounding will take most of the current upon itself. The contact of the phase with a grounded boiler tank leads to instantant operation of the circuit breaker.
Figure № 2. Wiring diagram in the apartment
Вводной электрощит дома – input electric board of the house
Электрощит внутри дома – electric board inside the house
Освещение - lighting
Розетки-кухня – outlets on the kitchen
Вводной автомат – incoming switch
Электросчетчик – electric meter
УЗО (на вводе) – RCD (on the input)
Однополосный автомат – one-tape automate
Нулевая шина – zero bus
Шина заземления – grounding bus
Why you need to ground household appliances
According to the established standards, the voltage in household electrical systems can not exceed 220 V. Household appliances are connected to the networks through sockets. There are two wires to each outlet. One of them, called phase, is directly current-carrying conductor. The second wire, called zero, serves to drain electricity after the contacts of the socket and the switch are closed.
If the phase and neutral wires come into contact outside the outlet, a short circuit occurs. In such situations, the current reaches a high value, which leads to the activation of circuit breakers, which perform a circuit break and disconnect the wiring from the power supply.
Real short circuits are quite rare. Wearing of insulation more frequently leads not to the closure of two wires, but to the appearance of leakage currents. As a result, the voltage that has appeared on the body of household appliances can lead to electric shock. Leakage currents should be fixed by a residual current device (RCD), which opens the circuit in case of exceeding the dangerous current for a human.
Grounding rules for appliances
For the grounding of appliances, a special design of the socket with ground contacts is required. There is a grounding point of the appliance on such sockets. If connection of the ground wire directly to the housing is foreseen, the grounding is indicated on the appliances with a special sign.
Figure №3. Socket with grounding contacts
A three-wire cable must be connected to the outlet. Modern cables used for wiring have three wires, which are marked with different colots for identification. The zero wire is colored in blue, the phase wire is brown or black. The third conductor is grounding, it can be yellow, green or two-color (yellow+green).
Figure № 4. Cable with a grounding wire
With three-wire networks in the apartment, the phase, zero and grounding must be taken in the distribution panel, relating to the line of outlets. Grounding of appliances, in the case when the wiring is two-wire, is done somewhat differently. With two-wire networks, when there is no ground wire, it is conducted from the electrical board. It should be noted that the cross-section of the copper ground conductor must not be less than 2.5 mm. It is strictly forbidden to use water and gas pipes or central heating pipes as a grounding conductor.
Universal modula grounding
When organizing electrical safety in residential and industrial facilities it is convenient to use ZANDZ modular grounding. This type of ground electrode consists of copper-plated steel rods. All components of the structure are integrated into one single grounding device by means of a threaded connection. At the same time, welding of grounding elements is not required, all the installation is performed by one person with a jackhammer. The ground area occupied by the ground electrode is less than 0,6 m2, due to which it is possible to mount a modular grounding in the cellars of houses and in the immediate vicinity of the walls. Copper coating of grounding rods is resistant to corrosion, which ensures stable grounding operation for many years.
Possible variations of modular grounding:
deep-laid ground electrodes
have a small number of vertical electrodes that are placed at great depths
conventional ground electrode
has a large number of vertical electrodes, which are located at shallow depths
special ground electrode
this type of grounding is made for container objects
Grounding can be purchased in the form of ready-to-install kits or individual components.
Correct design and installation of grounding of residential and industrial facilities is the basis of electrical safety. In order for the grounding to perform its functions fully, it must be of high quality. Do not save up on safety! Use high-quality grounding by ZANDZ!!
- Instruction: grounding and lightning protection for a private house, cottage, cottage
- Grounding systems TN-S, TN-C, TNC-S, TT, IT
- Protection of a private house from overvoltages
- Lightning protection of a single-family house
- Find an Eepert in your region