Cross-circuit - Circuit diagram for changeover switches with 3/4 switches

• Difference - buttons, switches and knobs
• Typical applications for cross-connect
• The crossed circuit
  • circuit diagram
  • Advantages of the cross-connection
  • Disadvantages of the cross circuit
• Tips for quick readers

Crossover is a simple and inexpensive solution to light a large room with multiple doors. Normal on-off switches are not appropriate in this case. To turn it on, all switches should always be set to "on", while only one switch must be set to "off" to turn them off. A crossover can, to some extent, provide a comfortable solution here. Learn in this guide what to look for when installing a crossover.

Attention: home electrics is a matter for the expert!

The information described here is a general description and no instructions for rebuilding! Rely on the help of a specialist in everything that goes beyond low-voltage electronics up to 24 volts! You put yourself and others at risk if you make changes to your home installation without training or experience. We assume no responsibility for consequential damages resulting from attempts of imitation of these general descriptions!

Difference - buttons, switches and knobs

When dealing with electrics and electronics, it is important to separate concepts from each other. This is particularly important for reading and creating the circuit diagram and circuit diagram. Therefore a little digression:

Switch: A switch has a defined "on" and a defined "off" position. Once switched on, it maintains the switching state.

Pushbutton: A pushbutton switches to mechanical pressure from one defined position to another. When unloading the button jumps back to its original position and resumes the original switching state.

Controller: A controller responds via a sensor to its environment and switches according to a permanent target / comparison in a desired position.

Relay: A relay is a "mediated switch". It switches a circuit by itself getting a pulse or impulse.

Typical applications for cross-connect

A light switch is usually located at waist height next to an entrance door. As long as the room has only one door, a simple on-off switch is sufficient. For large rooms that have multiple entrances, however, things get complicated: If you were to use only normal on-off switches, the room would only be lit when ALL of the switches are "ON". As soon as one switch is switched off, virtually all the others are also dead. So it is a different solution needed when a room is to be powered by several switches with luminous flux.

The simplest solution for multiple switching

If a lighting or another consumer is to be controlled via several switching points, the use of push buttons and a relay is the simplest solution. The actual power supply is controlled by an electronic relay. The relay, usually a spring loaded magnetic switch with automatic reset, can then be controlled by any number of buttons. The relay circuit can be recognized by the fact that there are no normal toggle switches, but pushbuttons with automatic reset function. In addition, one usually hears a characteristic buzzing from the electromagnet in the relay for the duration of the button press. The advantage of these circuits is that any number of switches can be connected to them. This safe and simple solution has only one drawback - it is slightly more expensive than a normal cross-over. With only a few switching points, this solution is therefore sufficient in many cases.

Changeover switch for comfortable wiring

The peripheral switch of the crossed circuit is the changeover switch. This module basically consists of two switches in one: when it is tilted, one circuit closes and another one opens. A clever combination of toggle switches and cross-type switches can be used to create a convenient wiring for decentralized control of a circuit. A change-over switch usually has three, sometimes four, connections.

Cross switch for reversed polarity

The cross switch is the heart of the cross circuit. The difference from the crossover switch to the changeover switch is that the crossover switch does not open a separate circuit, but reverses the polarity in a circuit. Therefore, the cross switch is also called Polwender . He has basically four connections. Cross switches are of course used for crossed circuits. In addition, it has a certain importance for the drive of electric motors. With the cross switch you can easily change the direction of rotation of the electric motor. Typical applications are: drives for blinds, garage doors or rack and pinion drives.

The crossed circuit

As a rule of thumb you can remember: Up to three, maximum four limit switches, a cross-circuit makes sense. In addition, a switch circuit, ie a circuit with an intermediate relay, should be avoided. This is technically a bit more expensive and expensive. Once the relay is installed, however, any number of buttons can be connected.

Before you start: The five safety rules of electrical installation

The VDE has issued five safety rules for working with electrical installations. If these are always observed, the risk of a power accident can be minimized. The security rules are:

1. Unlock
2. Secure against restart
3. Prepare unencumbered apolig
4. Grounding and shorting
5. Cover or restrict adjacent live parts

Unlock: This means that a circuit must be de-energized. For this purpose, it is not enough to operate a light switch, but it is absolutely necessary to switch off the relevant fuse at least! however, it is ideal to switch off all fuses, including the FI switch. Fuses are simply turned out.

Secure against reconnection: This is particularly easy with fuses: The electrician simply puts the pieces in his trouser pocket and prevents them from being turned back in again. LS-switches, ie normal tip-fuses have a small double hole, which is accessible as soon as the fuse is switched off. Through this hole fits a thin wire, such as a straightened paper clip. If now additionally a sign is attached, which points to the off state of the fuses, an inadvertent or negligent restarting is largely excluded.

Determine zero voltage apolig: The absence of voltage of the cables is NOT determined by a "current tester". The illuminated screwdrivers are no longer permitted today and have been tested in the past for numerous power accidents. To determine the absence of voltage, only a polisher or a multimeter may be used. In principle, all incoming wires are tested against each other on a box. Hobby suitable for use Polprüfer cost from 25 €, professional equipment from about 100 €.

Grounding and short-circuiting: This step is actually only prescribed from 1000V. But it is also useful when handling 220 volts. When grounding, the ground line (black) is briefly closed against the protective line (yellow-green). This has the advantage that the FI switch triggers immediately if someone switches the fuses back on.

Cover live parts: all cables not in use should be covered. For this purpose, plastic film, buckets, bowls, leather or rubber hoses are suitable.

circuit diagram

If a circuit of only two different switches to be turned on and off, two changeover switch suffice. For three to four switches, the cross circuit makes sense.

The cross switches and the changeover switches are connected with two lines each. One of the lines carries electricity, the other not. Thanks to the integrated cross switch, the further conductors change state. What was previously "switched on" becomes "switched off" and vice versa.

The circuit diagram for the cross-connection requires a five-core, but at least a four-core cable! This installation does not work with a 3-wire cable. The switches are wired together in series. It is therefore only a current-carrying cable necessary. With multiple live leads the crossover does not work either. The connecting, five-wire cables, which are led from box to box, are called "corresponding wires".

The wiring diagram is basically quite simple: The FIRST and the LAST box between the power source and the power consumer is equipped with a changeover switch. All other switches in between are executed as a CROSS switch.

First, all neutral conductors and protective conductors are connected to each other by means of terminal blocks, plug-in terminals or WAGO terminals. The corresponding conductors remain between the AC and DC switches.

The phase, the incoming, live cables, is plugged into the solitary connector in the toggle switch. It now powers both outputs, no matter how the changeover switch is switched. The active switching points are clearly marked on the toggle switches. As a rule, they are outlined in black. At the equivalent output point of the last toggle switch, the consumer, eg the light source, is also connected to the solitary plug-in point.

One of the three remaining colors of the five-wire conductors is not needed. The two other wires are simply connected to the remaining plug-in points of the change-over switch. Finally, the cross switches are connected in series with the same colored wires. It is important that the incoming and outgoing cores are wired side by side and never cross-wired.

Advantages of the cross-connection

• Simple circuit diagram and simple installation
• The relay or the impulse switch is omitted. This makes the price advantage of this solution for smaller circuits.
• If the recommended five-core cable is used, it is very easy to implement an electrical outlet afterwards. This is especially true if you want to switch to a surge circuit later.

Disadvantages of the cross circuit

• The cross circuit is determined by circuit diagram. Expanding it later is very difficult.
• Cross switches are more expensive than simple switches or buttons.
• If a switch fails, the whole installation is broken.
• The required four- or five-wire cable is more expensive than the two-wire cable of a button.
• A push-button circuit is easier to combine with a timer.

Tips for quick readers

• Always have the circuit diagram and circuit diagram checked by an electrician
• Use high quality switches and tools
• Use professional, two-pole phase testers
• Do not use cheap power meter screwdrivers ("lying pins")
• Do not provide more than two cross circuits in the circuit diagram
• Switch from four switches to surge circuits
• First loop and test earth and protective conductor.