How to properly ground the washing machine with your own hands

Electrical assistants have firmly and permanently entered our lives. They facilitate the performance of routine homework, save a person from monotonous physical labor. Therefore, manufacturers of household appliances are constantly improving their products, providing them with new features and improved capabilities for operating conditions with increased safety.

However, in real life, for some reason, it turns out that a new serviceable washing or dishwasher is shocking and requires grounding. Let's try to figure out why this is happening and how to do the right thing in this situation.

Why the washing machine is shocking and requires grounding

How does a new working technique work?

Modern production is designed to produce household electrical products designed to work in three-phase wiring. She is connecting grounding system TN-S using a separate PE conductor, providing reliable electrical connection of each household appliance with the ground loop of the mains.

In most of our old high-rise buildings, this requirement, which is necessary for safe living of people, is still not fulfilled: electrical wiring works two-wire circuit TN-C. Residents connect to it all the equipment that they buy in the distribution network.

In this case, the discrepancy between the technical standards of these two different grounding systems immediately arises as a result of the improved design of modern household appliances. They are equipped with a surge protector.

In this circuit, we see two series-connected capacitors. They are connected to the potentials of the supply network (phase and zero), and their midpoint is displayed on the housing. Due to this, 110 volts appear on it.

To prevent the midpoint potential from causing harm to humans, the case is used to connect the building to the building's grounding loop due to internal installation with a jumper connecting the metal parts of the washing machine with the grounding terminal of the power cord plug.

When a plug is inserted into a socket in a three-wire circuit, thanks to the use of a PE conductor, the potential of the midpoint of 110 volt capacitors flows through it to the ground circuit.

But when connecting the washing machine to a two-wire network, this is not possible. It turns out that the voltage is present on the case.

The discharge of these capacitors to a person usually does not create serious injuries due to low power, and the technique usually stands on ceramic tiles, laminate or linoleum, which have good dielectric properties. Therefore, a person feels "tingling", simply pulls his hand away from the body.

However, it is worth considering that the current, although of a small size, passes through the human body. Since the washing machine is located inside the bathroom or in the kitchen, where increased humidity is periodically created, the situation with electrical injury can be aggravated.

In this case, one of the two options for resolving the issue for a two-wire power circuit suggests itself:

1. ground the washing machine according to the scheme developed by the manufacturer;

2. disconnect the midpoint output of the capacitor filter from the housing until the reconstruction of the building's grounding system.

There is a third method: “leave it as it is,” which is used most often, but it is not entirely reasonable.

How is the protection in case of breakdown of the insulation of the washing machine

Since we now live in transition time and in our apartments the electrical wiring can work according to the TN-S, TN-C-S or TN-C grounding schemes, we will consider both of these options.

Protection of the washing machine against leakage currents in a three-wire network

Manufacturers of electrical household appliances take into account that during operation in any place, for various reasons, a violation of the dielectric insulation layer can occur. In this situation, the potential of the network begins to penetrate the device’s body through the damage site. Therefore, it is pre-grounded to the ground circuit.

Due to this connection, in case of violation of the insulation layer, a leakage current from the supply network begins to pass. In a dashboard specially set residual current device - RCD or differential machine.

They have an organ for comparing currents that flow through a phase wire from the power supply to the electrical device and return through the neutral conductor. The magnitude of these vectors in normal mode is balanced.

If an emergency mode occurs, when leakage currents to the case are created, then part of the current no longer flows along the neutral conductor and an imbalance is formed in the comparison organ, which is calculated by logic. She gives a command to disconnect the power contacts of the RCD of the phase and zero potentials.

In this way, the malfunctioning washing machine is switched off when insulation defects occur in it without human intervention. To ensure safety, the response setting of the UZO of household appliances is selected for leakage currents of 30 milliamps, and for washing machines operating in kitchens and inside bathrooms - 10.

Protection of the washing machine against leakage currents in a two-wire network

The use of RCDs in the TN-C system is not as effective as in the TN-S and TN-C-S schemes. The fact is that if a breakdown of insulation occurs, then there is usually no way for dangerous potential to drain from the housing.

After all, the washing machine is not connected to the ground loop and is installed on a dielectric base. Therefore, when a person touches a case that is under voltage, then again a leakage current is generated through his body to the earth circuit.

However, in this case, the RCD can detect that the current flowing through the neutral conductor has become less than the phase conductor. Due to this, the logic circuit disconnects the power contacts of the protection, significantly limiting the time of the emergency mode through the human body. The victim will receive much less damage than without the use of such protection.

For this reason, it makes sense to install protection with an RCD in the apartment panel for the washing machine, even when using a two-wire household power supply according to the TN-C scheme.

Grounding methods for the washing machine

To connect the housing to the ground circuit, it is necessary to provide reliable electrical communication. In all household washing machines, it is created through the grounding contact of the plug with a power outlet.

Although you can find designs where there is an additional ground terminal. It is located directly on the rear side of the housing, has electrical connection with the grounding contact of the plug. It can be called up by the tester in ohmmeter mode. Use of this terminal is convenient for those owners who live in private houses with TT earthing systemusing individual circuit.

In multi-storey buildings, the connection method through a plug with a socket is usually used.

At the same time, residents of apartments equipped with electrical wiring mounted according to the TN-C-S system should be presented with a scheme for dividing the PEN conductor in the building's switchboard into working and protective zeros.

In new buildings under construction in urban neighborhoods, such separation is carried out directly on the ground loop of the transformer substation and is called the TN-S system.

Errors allowed when grounding the washing machine

Most often found:

1. grounding of the body instead of grounding;

2. connecting the case to random grounding conductors.

What is the danger of zeroing of household electrical appliances

Looking at the scheme of separation of the PEN conductor into PE and N, individual craftsmen see that their wires on the main ground bus are combined. On this basis, the erroneous conclusion is made that directly in the socket it is possible to jumper the contacts of the protective and working zeros, thereby eliminating the laying of one wire, creating material savings during the installation of the circuit.

However, this is a gross erroneous opinion, as a result of which the safe work of the defense is disrupted. Let us analyze the positive and negative aspects of this circuit, which in practice is called zeroing, when the metal case of an electric device is shunted directly to a working zero.

The advantage of the circuit is that during the breakdown of the insulation of the electrical appliance, the phase potential immediately connects to the zero potential, a short circuit occurs in the circuit and the circuit breaker works, quickly disconnecting the emergency device. Due to this, the duration of the passage of short-circuit current is significantly reduced, on the path of which a person can be.

However, with this method, two dangers that can occur at any time remain hidden:

1. the invited electrician or home master during the repair of the wiring disconnected somewhere the ends of the two-core power cable and mixed up their places when connected;

2. someone from the household pulled the plug of the power cord of the washing machine from the outlet and then inserted it, replacing the polarity of the wires, just turning the cable over.

In both situations, a dangerous phase potential will be present on the body of the electrical appliance, even with good insulation. Any person who touches it is affected by tension. It is necessary to create additional contact with the water supply, heating battery or other live part connected to the ground, as an accident is provided.

The danger of using random grounding conductors

It is quite clear that the owner of an apartment equipped with a three-wire electrical wiring system has all the conditions for connecting a washing machine according to the standard and safe power scheme. He does not need to engage in amateur performances. Everything is already prepared: just plug the plug into a grounded outlet.

Those owners who live in old houses with a two-wire power scheme according to the TN-C scheme begin to take the initiative. They began to realize that the health of themselves, as well as other family members, was at risk, taking rash actions, arbitrarily connecting to water supply, heating, elevator equipment and any other devices with random grounding conductors.

What are the dangers of this method:

1. there is no guarantee of tight metal contact of such a device with the ground potential. For example, part of the metal pipes of the water supply system, any apartment owner living below can replace it with polypropylene during repairs, and water does not always fill them completely. Here is the chain and is broken;

2. Inside the power supply network, emergency situations can occur when a dangerous potential begins to flow to random grounding conductors. According to them, he will go through a makeshift connection to the housing of a household electrical appliance;

3. When creating a house project, all kinds of construction calculations are made, including analysis of various cases of accidents that can occur in the electrical circuit, taking into account the flow of currents in grounding conductors and soils. Even a correctly installed ground loop, for example, inside the basement of a building can affect the pattern of their distribution. Therefore, it requires preliminary calculation and coordination with the operating organization.

How to ground a washing machine in a two-wire household network

What remains to do to the owners of electrical appliances living in old buildings with a two-wire power circuit? The most prudent is not to show excessive initiative than to exclude ill-considered actions with household wiring.

All old buildings in a planned order of priority will be transferred to a power supply system via the TN-C-S grounding system. In this case, a normal protective PE conductor will be connected to the floor and apartment panel and connected to the PE bus.

And here comes the turn of the owners of the apartment, as the owners of the premises. They will have to carry out their own wiring on all domestic consumers. This work is quite expensive, dirty, time-consuming, especially when laying cables and wires inside the walls.

It will have to be carried out in any case, but it can be combined with the current repair and all the wiring should be replaced in advance for connection according to new standards. The only safety condition is to fully prepare the PE conductor, but do not connect it anywhere: neither in the shield, nor in the outlets.

What happens if you connect the PE conductor on the outlet side

Let's pay attention to the very first picture, which shows the connection of modern household appliances using a filter to reduce high-frequency interference in a household network. We have already considered that a potential of 110 volts will be present at the midpoint formed by capacitor separation.

This means that it will appear on the grounding pin of the plug and go through it to the outlet where the newly mounted PE conductor is connected. If the latter is connected to its bus, then this potential transfers to it. When he just hangs in the air, it can also cause trouble.

Therefore, it is most optimal to connect it anywhere and on no side at all. This is not difficult to accomplish when reconstructing the building’s power supply circuit.