Installation of electrical wiring in a house or apartment is a laborious and responsible process. However, laying cables and wiring is not the most important thing. The most important task in this work is the installation of a switchboard, in which, in addition to the electric energy meter, automation is installed that ensures the safety of residents. One of the most important elements of the entire system is the residual current device. Today's article will take a closer look at how to connect the RCD correctly, the difficulties that a home master may face when switching, the most common questions related to such work, and the answers to them.
The principle of operation of the residual current device
The main units of the RCD can be called two coils through which phase and zero flow. With stable operation of the network, there is no potential difference between us. However, everything changes when a phase or neutral conductor breaks down on the case. In this case, part of the current goes along the path of least resistance togrounding. As a result, the device detects an increase in the potential difference, recognizing it as a current leakage and works, opening the circuit and removing voltage from the line. Thus, a properly connected RCD ensures the safety of a person, his protection from electric shock.
Assignment of residual current device
Many do not fully understand what the RCD is intended for. It makes sense to understand how it differs from a conventional circuit breaker (AB). Mainly, the residual current device works for human safety in the event of a breakdown of insulation on the housing of a household appliance. After all, almost everyone has come across a situation where, when touching the metal parts of kitchen or other appliances, a slight, but rather unpleasant electric shock is felt. However, this is not always harmless.
There are times when such situations end in death. A residual current device is just installed to prevent this. However, a significant problem for home craftsmen is the correct connection of the RCD in the shield. Even experienced electricians often make mistakes at this stage of installation, which means that you should deal with this issue in more detail.
Mistake No. 1: if there is an RCD, the installation of the machine is not required
Such a delusion is quite dangerous. The problem is that the RCD is able to detect leakage current, but is completely immune to short circuits and network overloads. ATif they occur, the residual current device will simply fail. At the same time, its contacts “stick”, as a result of which the line on which the short circuit occurred remains energized, the wiring continues to heat up until the insulation ignites. As a result - a fire and the loss of all property, possible harm to he alth or death.
Conclusion: only the correct connection of the RCD and circuit breakers in the electrical panel can provide full protection for the home power network, equipment, life and he alth of residents.
Mistake 2: grounding and zeroing are the same thing
This question is worth considering with examples:
- Ground and neutral wire touch on the line after the RCD. With such switching, the residual current device will operate for no particular reason, identifying non-existent leaks. This means that using such a line will be extremely problematic.
- Earth is missing. A two-wire system is indispensable here, which means that you will have to mount a protective grounding. To do this, an additional bus is installed in the shield, to which zero is supplied from the counter. The main thing is that the neutral is removed before the residual current device, in order to avoid unreasonable operations.
When properly connected RCDs and circuit breakers, closing the ground and neutral contacts in the socket will lead to a cutoff.
Let's move on to the next error.
Mistake 3: Tomake the correct connection of the RCD, the circuit is not required
Usually, such a delusion is inherent in experienced craftsmen who rely too much on their memory. However, practice shows that when assembling an electrical panel (regardless of its complexity), even a hand-drawn project speeds up and greatly simplifies installation. In addition, later, when repairing a power home network, this scheme can help a lot.
Joint connection of RCD and additional equipment
In addition to AB, along with a residual current device, other equipment is installed in the switchboard that can ensure the safety of household appliances. For example, connecting an RCD and a voltage relay. How to execute it correctly so that, together with the machines, an integrated scheme is created that will protect against any force majeure situations that may arise? Of course, here much will depend on the availability of free space for mounting modules and financial capabilities, but the main thing is to strictly follow the manufacturer's instructions and advice, which can be found in the technical documentation.
Also, residual current devices are compatible with any relays and sensors. The wiring diagram of the automation does not change. And in order to make it clearer how such a device is connected, you can see the video below.
How to properly connect an RCD without grounding
Not even all experienced electricians know the answer to this question, which means that it is worth dwelling on it separately. Toinformation was perceived easier, it makes sense to consider the algorithm of work step by step:
- First, all protective automation and an electricity meter are placed in the switchboard. It is very convenient if 2 DIN rails are provided for this. In this case, the top one is occupied (from left to right) by an introductory machine, a counter, an RCD. The lower one is for AB by groups.
- Be sure to place two contact tires in the shield - zero and ground. Between themselves, they must be closed.
- From the electric meter, the phase goes directly to the RCD, the neutral wire goes to the bus, and from it to the residual current device.
- Now the main wiring is done. RCDs are not required for lighting groups, which means that zero for them will come from the bus. For the rest, the neutral is taken from the output of the RCD. Thus, the correct connection of RCDs and circuit breakers without grounding provides a complete three-wire system that uses high-quality protective grounding.
Commutation of the device in three-phase networks
Some may think that working with 380 V is much more difficult and less convenient, but this is a delusion. In fact, three-phase networks are simpler than it seems at first glance. In addition, with 380 V, more opportunities open up in terms of switching.
The question of the correct connection of a three-phase RCD begins to be solved by drawing up diagrams in groups. The main thing here is to distribute the lines so that the load on them is relatively the same. If ahowever, all household appliances should be connected to one phase, a distortion will occur, which will pull power surges on the other two.
Power input to the RCD is carried out similarly to the previous option, with the only difference being that not 2, but 4 wires are used. At the output we get a common zero and 3 separate lines of 220 V.
Using multiple residual current devices
When it comes to a large private house with a lot of household appliances, a separate RCD is often required for one line or another. For example, most often this is necessary when supplying power to electric boilers, washing machines and dishwashers. In this case, the wiring diagram in the switchboard will be slightly different.
The main RCD remains in place, it also feeds low-power household appliances. However, in addition to them, voltage is supplied to the secondary protective shutdown devices, from each of which there will be a separate line to a particular device. The main task here is not to confuse the zero conclusions with each other, which often happens when a self-confident master assembles a switchboard without a circuit. And here's what happens. The electrician takes the phase wire from one RCD, and the zero wire from the other. As a result, both residual current devices begin to operate for no reason. But it will be much more difficult to sort out an already mounted switchboard than to initially do everything according to the rules.
Basic steps for DIY switchboard layout
The first thing to do is to mark the cables coming to the closet from the premises of an apartment or a private house. The tags should contain information about which room the wire came from, the number and total power consumption of household appliances that will be powered from it. Further, on a piece of paper in an arbitrary form, the location of the elements of protective automation is drawn with notes on which cables should be connected to them. In fact, for many, this information is enough to correctly connect the RCD and other equipment necessary to protect the network without any problems.
After placing the elements in the switchboard, it makes sense to duplicate all the information from the diagram on the box door and number the AV, RCD and other automation.
Basic Rules for Switchboard Power Supply: Tests
Installation and wiring in the cabinet are made from the introductory machine. However, the main rule should be observed here - it should not be powered. Voltage is applied to it last, after the completion of all switching work. Having connected the input cable (the supply is turned off from the feeder or other switch), you should make sure that all the “flags” of the protective equipment are in the “on” position. After that, voltage is applied to the switch cabinet. If the RCD connection is correct (the same applies to AB), all the "flags" will remain in their original position. It remains only to press the "TEST" button on the RCD, which simulates the currentleaks - cut-off must occur.
Checking the correct connection of sockets is checked in the simplest way. Using an indicator screwdriver, there is a zero contact, which must be bridged with a ground contact. If everything is mounted correctly, the RCD will work.
In conclusion
Know how to properly connect and check the residual current device, every home master should. This will ensure the safety of people living in the house or apartment. The main thing is to observe the rules of electrical safety during all work and not to work with equipment that is energized. After all, electric shock is life threatening.
