Changeover switch: markings, types, connection features

A changeover switch, or as it is also called marching, double, reversing, cross, is an element of the electrical network that inverts (translates to the opposite state) the switching of conductors connected to it.

A rocker switch is used to control a group or one lighting fixture from several locations.

In this material we will talk in detail about the principles and features of the operation of such switches, and also give the most common methods of connecting them.

Scope of application of changeover devices

Changeover switches are not used so often, but their role in organizing lighting cannot be underestimated. Imagine a situation where there is only one switch installed in a long corridor or at the beginning of a flight of stairs and you have to walk considerable distances in the dark to turn on the light.

Installation pass-through switch two directions is quite capable of solving this problem, and a reversible (cross) direction will become indispensable:

• in a three-level apartment - installed near the second floor landing;
• in a large corridor or hall - installed near each door, it will greatly facilitate movement in the dark;
• in the bedroom - you can install one near the door and two near the resting place, and you no longer have to get up to turn off the light.

You can also use a rocker switch to turn on lighting on the street or in the garage, controlling the lamp from the house, gazebo, terrace, etc.

When leaving the room into the corridor at night, the user can turn on the light immediately, rather than moving around in a dark room looking for a switch

Types of changeover switches and their markings

The choice of changeover switches has to be made based on a modest list of distinctive characteristics. They are produced by many well-known companies, including Legrand, ABB, Schneider.

Lever electrical equipment is considered more reliable and therefore is often used in factories and public places

Changeover switches are classified:

1. According to the method of activation, they are divided into rotary, key and lever types;

2. According to the installation method - for devices for internal and external installation.

You won’t find two-key cross-type toggle switches as such on sale. But you can use an Ultra series device from the well-known electrical equipment supplier Schneider Electric by taking two modular-type single-key crossover units and installing them in one housing. If these models are not available, two single-key switches are mounted side by side.

To control two or three groups of lighting fixtures, two or three-key pass-through switches are used, and cross switches, in most cases, are installed separately for each group of lamps

When choosing any electrical device, you must focus on its protection class from external factors - IP.

In most cases, in devices of this type, the IP is quite high and exceeds 40, which allows for use in rooms with traditional high humidity, as well as outdoor location under a canopy.

In rotary changeover switches, the contacts are closed using a special rotary mechanism. They cost a little more than keyboards, but are considered more reliable

In order to correctly connect electrical equipment, it is important to understand the symbols and diagrams printed on the back by the manufacturer.

This is how the diagram indicates a cross-type switch. The same diagram is applied to the device, the arrows show the location of the input and output contacts

If in a conventional switch the marking with the letter L is used to designate the incoming phase terminal, and L1, L2, L3 for the outgoing ones, then in the case of a paired switch the numbers 1, 2, 3, 4 can be used, and the incoming and outgoing terminals are indicated by arrows.

Manufacturers also sometimes put markings on the front side of the switch - for a walk-through switch these are two arrows in the form of a triangle, for a changeover switch - a grid

Next, we will look at the installation features and options for possible connection diagrams using the example of a household cross-type changeover switch complete with adapter switches.

Operating principle and features of changeover switches

To understand the operating principle of a cross-type rocker switch, it is necessary to study the control circuit for lighting points of 3-5 points.

But since cross switch always installed between walk-throughs and never used on its own, you first need to understand how the lighting activation and deactivation circuit works with conventional and walk-through switches.

Three-point lighting control circuits differ from a two-way circuit only in the presence of a cross switch

So, the functions of a regular switch include opening and closing the circuit - when you press the upper half of the key, the light turns on, the lower half turns off. But the state of lighting in a circuit with two pass-through devices does not depend at all on the position of the keys of one of them.

Pressing a key only switches the connection from one circuit to another. In order for the circuit to close, it is necessary for both devices to make contact with one of the conductors laid between them.

A pass-through switch is also called a two-way switch. The diagram clearly demonstrates that the user, using any of them, will be able to turn the light on and off

The mechanism of different types of devices differs in the number of terminals:

• in the usual there are two;
• in the transitional there are three;
• in a cross connection there are four terminals.

The more complex the device, the more quality it requires. Therefore, the design of rocker switches, which have a large number of terminals, is distinguished by high strength, wear resistance, and corrosion resistance.

Most models have a high level of protection (IP) from negative external factors - dust, moisture.

If pass-through switches are always used only in pairs, then the number of changeover switches can be any - at least one, at least ten

Just like pass-through switches, crossover switches switch connections from one conductor to another. But their difference is that there are already two input contacts, not one, and their switching also needs to be controlled. The operating principle of the device is based on paired switching of contacts.

Connection options

Just as pass-through switches cannot be used individually, but are connected only in pairs, so changeover switches are used only with two pass-through switches. In this case, up to 10 cross switches can be used, and they will always be located between the pass-through switches.

In the diagram, the phase conductor is indicated in red, the neutral conductor in blue. A 1 - basic connection diagram; A 2 is another version of the connection diagram; B1 - wiring method, in which each element of the circuit is connected through a distribution box; B 2 - connection method using an old small junction box and a socket from under a dismantled conventional switch

There can be many options for circuits used for connection: installation is carried out through a distribution box or past it, several lighting groups are connected.

They will improve the system by installing centralized control.

The cross-type changeover switch device is always designed for one lighting group. If it is necessary to connect two groups of lamps, use either two switches or make up one of two separate blocks

Installation via junction box

This is a traditional connection method, which has both disadvantages and advantages. The advantages include the ability to quickly detect damaged sections of wires in case of problems in the circuit.

In addition, this method involves the traditional laying of wires, which helps during subsequent repair or installation work to determine where the wires are laid and maintain the integrity of the electrical network.

Connection diagram for pass-through and cross switches in a lighting control system from several places.L - phase conductor; N - zero

When installing electrical wiring from the junction box to the pass-through switches, three-core wires are laid. A two-core wire leads from the crossover switch to the feedthroughs.

The sequence of actions when connecting a circuit in which the wires pass through a junction box is as follows:

• A two-core phase wire from the electrical panel is inserted into the box. The neutral conductor of the supply cable is immediately connected to the neutral conductor of the lamp, and the phase conductor is connected to the common conductor of the first pass-through switch No. 1, to input terminal 1 (see figure above).
• The remaining two conductors of the three-core wire are connected to output terminals 3 and 4, which in the junction box will be connected to the two conductors of changeover switch No. 2.
• Install the middle changeover switch. The correct connection of the crossover switch conductors is indicated in the diagram drawn on the device itself.

The second pass-through switch is connected in the same way as the first, but the common conductor is routed through the junction box to the lamp.

Laying an electrical network for organizing lighting using distribution boxes is good because in the event of a malfunction it is easier to identify the damaged section of the electrical wire

If the connection in the junction box was made by twisting, all exposed areas are carefully insulated to prevent a short circuit.

This is done using electrical tape or heat-shrink tubing, which can serve as a marking for the conductors.

We also recommend reading our other material, where we talked in detail about installing a junction box. Read more - read Further.

A professional connection is immediately visible - all wires are laid compactly and neatly in the junction box

Direct connection method

Connections are the weak link in any electrical network - this is where oxidation occurs. Regardless of whether it is side clamps or spring clamps quick-release terminal blocks, they burn out first, the wire itself remains intact, since it is protected from burnout by a machine.

To minimize the number of connections, the connection is made without a junction box.

They also come to this connection method because users do not always want to see several junction boxes on their wall - these are additional elements that have to be hidden from view

How to install an electrical system without a junction box:

1. A cable with two conductors is pulled from the electrical panel - phase and neutral. The latter leads directly to the lamp.
2. The phase is connected to the input terminal of the pass-through switch. Two phase wires lead from the two output terminals to the cross wire.
3. Two phase conductors are laid from the output contacts of the reversing switch and connected to the second pass-through.
4. The common conductor from the second pass-through switching device leads to the lamp and closes the electrical network.

All wires must be marked during electrical installation work. Otherwise, next time, when carrying out electrical installation work, it will be difficult to identify their nature.

It will be quite difficult to fit all the conductors that are connected to each other in the socket box. Therefore, flatter and more compact terminals are used. You can also solve the placement problem by using large socket boxes - with a depth of 60 mm

You can hide distribution boxes in other ways.For example, by installing a box behind a suspended ceiling.

This option cannot be called a win-win, since in complex cases of breakdowns, the detection of a fault may not be limited to one box, and then you will have to remove the ceilings in more than one room.

Distribution boxes are also installed behind the suspended ceiling. In this case, they are all concentrated in one place, and access is provided by an inspection hatch

Check the correct connection like this: every time you press the key of any switch, including the cross switch, the state of the lighting should change - the light should turn off and on. Problems can arise if errors are made during the connection - the circuit is assembled incorrectly, the contacts are mixed up.

The cause of improper operation of the changeover switch can be eliminated only by thoroughly checking the connection directly at the installation site.

Typical connection errors

Ignoring the markings and diagrams printed on the switches leads to connection errors and incorrect operation of the circuit. The most common problem that occurs, especially when installing pass-through switches, is the user incorrectly identifying the location of the incoming contact.

It may be located differently on different devices, so you must read the markings. All the subtleties of choosing pass-through switches are discussed in this material.

If it is not possible to determine the exact location of the incoming terminal, then test the device with a multimeter or an indicator screwdriver

When connecting changeover crossover switches, problems arise if paired wires from pass-through devices are connected to terminals located on the wrong side.

Most often, the device involves a cross connection.

You should always check the circuit before connecting. The input and output contacts of the changeover switch can be located differently

Lighting with cross switch in TN-S network

Connecting a crossover switch in a TN-S power network, which is characterized by the separation of the working (N) and protective (PE) zero, has some nuances. Unlike the old, not entirely safe TN-C system, the electrical network conducted according to the new standards uses 3 wires when supplying single-phase voltage, and 5 when supplying three-phase voltage.

The wire that performs the function of zero (N, marked in blue) comes out of the electrical panel, passes through the branch box and is connected to the zero of the lamp. The ground wire (PE, indicated in yellow-green color) is connected to the ground wire of the lighting fixture.

Laying electrical networks using the TN-S system significantly increases the cost of materials, but reduces the risks associated with the operation of electrical equipment

How to establish centralized lighting control?

The control network from several places has a significant drawback - all the switches involved in it do not have a fixed position. Therefore, it is impossible to determine whether the light in the room is on or not if there is no electricity. Installing a conventional switch in front of the first passage eliminates this problem.

To the already known connection diagram for changeover and pass-through switches, one more element is added - a regular single-key one. Place him in the same room or take him to the front door. When enabled, it will allow the system to operate as normal. When turned off, the circuit will be completely de-energized and, regardless of the position of the switches, the light will not light up.

An even better way to improve centralized control is to use a pulse relay. It has great functionality and allows you to control a separate group of electrical equipment or lighting throughout the house.

Conclusions and useful video on the topic

Operating principle of a changeover switch:

How a changeover switch works:

Electrical connection TN-S (with grounding, PE):

Installing a changeover switch is not as difficult a task as it seems at first glance. To simplify the understanding of the principle and patterns of connection, you can understand the operation of a conventional single-key device, move on to studying the operation of the transition switch, and then the circuit diagram of control using a cross switch will seem quite simple. The main thing when installing it yourself is to comply with safety requirements.

If you have experience in installing a changeover switch yourself, please share it with our readers. Tell us what points you need to pay attention to. Leave your comments and ask questions in the block below the article.