Which RCDs To Choose For An Apartment Or House And Prevent Connection Errors

2023 Author: Philip Bishop | [email protected]. Last modified: 2023-05-24 22:24

The use of circuit breakers in the apartment
Home protection circuit breaker device
The principle of operation of an RCD without grounding
What type of RCD is applicable in houses and apartments
Differential circuit breaker calculation
Current rating of input machines, paired with RCDs
Installation errors
How to check the RCD for performance
RCD video connection errors

Those who are worried about protecting their households from electric shock, the question arises: how to choose an RCD for an apartment or house?

Due to the abundance of these devices by classification and type, you can buy the wrong thing, and all efforts to protect the family will be in vain.

This article will help you choose this device.

The use of circuit breakers in the apartment

An RCD at the entrance to a house or apartment is necessary to protect against the negative effects of electric current on the human body, which directly touched live parts of electrical equipment or its housing, which is energized, due to the failure of its individual parts.

Also, this device serves to protect the electrical wiring from fire during aging or damage to the insulation of wires and cables.

It should be borne in mind that the RCD is disconnected in the event of an earth leak, but if you take up the phase and the working zero, it will regard this as connecting the load and disconnection will not occur, which is fraught with tragedy.

Home protection circuit breaker device

The RCD device includes:

A toroidal core made of a specific grade of ferrite.
Two primary coils (in a single-phase RCD) made of copper wire with a cross section not lower than the rated load current.
One secondary coil of thinner wire and more turns.
An actuator designed to disconnect power contacts in case of current leakage to earth.
A test button with a resistance, necessary to test the RCD for operability, when pressed, which changes the currents in the phase and zero coil, which leads to the operation of the shutdown mechanism, a current amplifier (in an electronically controlled RCD).
Device body.

The principle of operation of an RCD without grounding

By and large, it does not need a grounding conductor for operation, since a phase and a working zero are used. These two conductors pass through a kind of current transformer with a control winding.

Let's assume a load of 10 amps. A current of this strength will flow through the phase conductor to the load. And passing through the load, it returns along the zero conductor with the same parameters. As soon as a person touches the boiler body, for example, in which the heating element has burned out and a potential appears on the body, then part of the current begins to go through the body into the ground and the difference in currents on the phase and neutral conductors changes.

These scanty changes are fixed by the control coil and transmitted to the relay, which in turn activates the release mechanism and disconnects the line from the power supply.

What type of RCD is applicable in houses and apartments

To the question of what type of RCD to put at the entrance to the apartment, the answer is simple - an automatic device with differential protection (type AC - for alternating current or type A - for pulsating and alternating currents), and an electromechanical release that does not require an additional power source. You need to buy a device of good quality, for example, the German company ABB. It has earned great popularity for its quality electrical goods, and reasonable price. This will provide a guarantor of reliability and safety.

Such circuit breakers, in addition to earth leakage tripping, provide protection against short circuit and overcurrent consumption. And your safety comes first!

Differential circuit breaker calculation

The first step is to calculate what maximum current can be consumed by electrical equipment in a house or apartment. We consider their total power in watts, which is indicated on the nameplates of the devices, then divide the power by the mains voltage, and we get the current in amperes.

For example: the total power of the devices is 4000 watts. We divide by 220 volts and get -18 amperes. Therefore, the machine must be at least 20 amperes.

As for the leakage current, 30 milliamperes are suitable for an ordinary apartment. These are most often found in electrical stores.

If there is a shower stall for especially damp rooms, then it is advisable to make a separate power line and install a 10 milliampere difavomat for greater safety.

For large mansions, where all the wiring can be up to a kilometer or more, an RCD at the entrance to the house is installed with a nominal value of 100 milliamperes and higher, since with such a line length, there is inevitably a leak that can lead to a false operation of the RCD. Next, it is necessary to connect an RCD in the shield for each group separately with a rating of 30 milliamperes of leakage current. This will provide protection for a specific area.

Current rating of input machines, paired with RCDs

The current rating of the machines connected with the RCD in the panel, both inlet and in groups, must be lower than the machines with differential protection. This is necessary so that the load in the network falls on conventional circuit breakers, since they are ten times cheaper than circuit breakers with RCDs.

Also, increased currents can cause incorrect operation of the RCD mechanism.

Installation errors

A common mistake when connecting ouzo in an apartment is that in sockets with grounding, a neutral wire that does not pass through an RCD and is used as ground is connected to a zero terminal in the outlet. This causes the differential protection circuit breaker to trip when trying to plug something into that outlet.

If this happens, swap the neutral wire at the grounding lug of the knockout socket.
You should also correctly connect the wires at the input to the device. Phase - to contact "L", and zero - to "N". This will ensure correct operation of the device.

How to check the RCD for performance

As already mentioned, the "test" button is provided for this.

But her work does not guarantee complete protection. To fully ensure that the device is working properly, it is necessary to simulate an earth leak once a month. This can be done very simply:

Take a two-pole LED voltage indicator of the "contact" type.
Locate the phase in the outlet.
Insert one contact of the indicator into the phase, and the other will touch a grounded conductor, for example, a radiator or metal water pipes. Also, if it is in the country or in a private house, just stick the pin into the ground and touch the other end of the pointer to it.

During normal operation, the RCD should trip as the LED leakage current is typically greater than 30 mA (milliamperes). Also connect one end of the cartridge to the phase, the other to the ground. The result should be the same. If the RCD doesn't work, it's time to change it.