This is how toggle and cross switches work. Basic installation guide.
I had been involved in the renovation of my house for a while. As it was an old house, I had to change the electrical installation, adapting it to the new distribution, much more diaphanous.
It is a job that I did myself, although I must admit that I had to retrieve the notes of the race to remember how toggle and crossover switches work.
The conventional switch
I guess we all know how a conventional switch works, but just in case we will explain it again. The facilities of our homes use a system of single phase alternating current, which is made up of three cables: the phase, which carries the current, the neutral, which closes the circuit, and the earth connection, which prevents the passage of current to the user in the event of an insulation failure.
When we are setting the switches, the only cable that concerns us is the phase cable, since the neutral and the earth connection must go directly to the light point. In the case of a simple switch, we simply have to pass the phase cable through it before taking it to the point of light, and thus we can control its on and off simply by opening or closing the switch key, which will or will not let the current pass .
The switched switch
Although we usually use this type of switch as simple, the vast majority of those that are marketed are switched. Its function is to allow control a point of light from two different switches, very useful for example in corridors, where a switch is placed at the beginning and another at the end.
In this case, the phase must pass through the two switches before going to the lamp in question, with the particularity that both switches must be linked by a pair of wires, which is what allows the light to go from on to off or vice versa when you open or close either of the two keys.
The best way to understand this is with diagrams. In the first we see how the current cannot reach the lamp because the second switch prevents it. However, if we activate the first, the current can already pass, even if we have not touched the second. If we then activate the second, the current does not reach its destination again.
In the image you can see how are the connections of a toggle switch. The capital L marks the input of the phase cable (or line) and the arrows where we must place the pair of cables that join this switch with its partner.
You will notice that there are a couple of holes in each place. It does not matter where we place the cables, and its purpose is to enable derivations and splices. For example, if we want to feed another switch for another lamp from a line cable that reaches the switch box.
The cross switch
We already know how to control a light with two switches, but what if we need three? For this we have the crossed switches, which combined with the switched ones, allow us to control a light with as many switches as we want. This is a common case of the double bedroom, in which we want to be able to turn on the light from the door and then turn it off from both sides of the bed (or the other way around).
The diagram is very similar to that of commutated switches, except that between them we must place a cross, which is a special switch with two crossing keys. Likewise, we must connect this switch to the switched through a pair of cables.
If we look at the operation diagrams, we see that the cross switch allows the circuit to be opened or closed by activating any of the system switches. Thanks to these switches, we can control a light from as many switches as we want, we simply have to introduce crossed ones.
In the image we see the difference with the switched switch. There is not input for the line, but four arrows that indicate where to place the pairs of cables that go to the switches. Important, it is convenient to use cables of different colors so as not to get entangled, because if we do not place them correctly, the system will not work.
I hope that with this brief explanation I have been able to help you understand better how toggle and crossover switches work. It’s those kinds of things that can drive us crazy when there’s no way for a lamp to turn on the way we want.
Photo | iStock
