Connecting light switches – step by step

The first way leads to the fuse box where the corresponding fuse is switched off – in case of doubt it is better to switch off all of them. If more than one person has access, put a note on it saying "working on electrical – must stay off". Use a voltage tester and first make sure that the line is actually disconnected.

Connecting your own light switch is doable with the right information and tools. Nevertheless: Everyone must know if he has sufficient expertise and be responsible for his own actions. We do not take any guarantee and no responsibility. Therefore, in case of doubt, we always advise to hire a specialist. Dealing with electricity is life-threatening.

Who hasn’t experienced this: at the end of a renovation project, you find yourself doubtfully standing in front of old, yellowed switches that are particularly eye-catching because of their placement. The solution is obvious: replace the light switch. If you have some basic knowledge of electrics, here’s how to do it. For reasons of space, you will always find the legend in the diagram where the wire or terminal in question appears for the first time. In case of doubt please have a look at the above graphics.

1. Not all light switches are the same

There are different switches for different applications. It does not matter whether you want to connect a flush-mounted or surface-mounted light switch. Here is a brief informative overview:

Switch type Use

On-off switch	This simple switch is used where a single switch is required to turn a single light on and off (z. B. pantry, guest WC u. a.). However also for this application today mostly also change-over switches are used and offered.
Changeover switch	Wherever two switches are required to switch a light at different points in the room – mostly in living rooms and bedrooms that have more than one door. So there you have to connect two light switches for an alternating circuit.
Cross switch	This switch is used when three or more switches should work together for one lamp, i.e. mainly in corridors. This is done by using two changeover switches and two or more cross switches between them.
Series switch	If two or three lamps are to be switched from one switch, a series switch with an appropriate number of rockers is used. This often occurs in rooms such as kitchens or bathrooms, where, for example, an overhead light and a light above the work surface or on the mirror cabinet are switched on and off simultaneously or separately via a switch.
Double changeover switch	This switch also has two rockers (like a series switch) and again operates two lamps, but with more than one switch in the room.

2. Cables and wires – what do the colors mean?

According to today’s guidelines, the protective conductor (PE, the ground) must always be green-yellow and the neutral conductor (N, which returns the current) must always be blue. The phase(s) – in multi-core cables and lines there may be several phases (live wires) – can be brown, black and gray.
However, this was different in the past, when there were usually red, blue and gray wires, with the red one being the protective conductor.

• View light switch on Amazon "

Important warning: do not rely on the wires being used and connected correctly when connecting a switch. Check every single one with the voltage tester before you start working – even the yellow-green (or red for the older ones) protective conductor. Unfortunately, amateurishly wrong wiring is very common. Also the designations of the switch manufacturers are not uniform throughout. Please check the manufacturer’s specifications to see which designation corresponds to the one used in our descriptions.

• remove the plug-in terminals
• Matching switches

3. Connect toggle switch as a single on/off switch

Ask yourself also: How to connect a light switch? Then you find here the simplest variant with a switch and a lamp.

1. Make sure that there can be no current on the wires (s.o.).
2. Old switch if necessary. remove before you connect the new toggle switch: to do this, pull off the rocker, remove the frame and unscrew and pull out the switch.
3. Check each wire with the voltage tester to make sure that no current is actually flowing.
4. In addition to neutral and protective conductors, if you connect a simple light switch, you will find two wires, the incoming phase and the outgoing phase, the latter is also called lamp cable, because this phase goes to the lamp.
5. Pull out all wires a little and, if necessary, shorten them slightly and strip them again (12 – 15 mm).
6. Connect the protective conductor with a terminal (Wago terminal) to the other protective conductor.
7. Proceed in the same way with the neutral wire and now carefully push the two connected wires backwards into the socket.
8. Look at the switch from the back and find the openings for the wires (slightly different locations depending on the manufacturer).
9. To connect, flip switch over and look for markings on back side.
10. Insert the brown (or black) phase into one of the two openings marked L until you feel or hear the copper wire click into place.
11. Plug the second phase into one of the opposite holes marked with an arrow or numbers – again until the wire clicks into place.
12. Now insert the switch, screw it tight and put on the frame and the rocker (depending on the manufacturer’s instructions).
13. Switch on the power again and test the switch.

Tip: If you want to release the wires from the switch again, press the small plastic wedges usually located on the side against the switch and at the same time pull the wire out of the opening with slight twisting movements.

4. Connecting two toggle switches

One lamp and two switches are common. In this case two toggle switches are used.

1. Make sure that there can be no current on the wires (s.o.).
2. Old switch if necessary. remove before installing the new toggle switches: to do this, pull off the rocker, remove the frame and unscrew and pull out the switch.
3. Use the voltage tester to check each individual wire to ensure that no current is actually flowing.
4. Pull out all wires a bit and if necessary shorten them a bit and strip them again (12 – 15 mm).
5. Protective conductors are always all plugged together with plug-in terminals and placed in the back of the box – likewise the neutral conductors with each other.
6. In addition to the neutral and protective conductors, there are three wires in the box, two so-called correspondents, which are purely connecting cables between the changeover switches, and one phase, the colors should be brown and black. The phase is the line, only one of which is in the box.
7. The phase comes into an opening, which are marked with L. Push in until you can feel or hear the copper wire click into place.
8. The two corresponding ones come into the opposite openings, which are marked with an arrow or a number – also until the wire clicks into place.
9. Now insert the switch, screw it tight and put on the frame and the rocker (depending on the manufacturer’s instructions).
10. Turn power back on and test switch.

5. connect cross switch

In case of a lamp with more than two changeover switches, one (or more) cross switches are used between them.

1. Making sure there can be no electricity on the wires (s.o.).
2. Old switch if necessary. remove the rocker, take off the frame, unscrew the switch and pull it out.
3. Use the two-pole voltage tester to check each individual line to make sure that no current is actually flowing.
4. Pull out the wires a little bit and if necessary shorten them a little bit and strip them again (12 – 15 mm).
5. Protective conductors are always all connected together with plug-in terminals and placed in the back of the box – as well as the neutral conductors with each other.
6. In the case of the cross switch, there are then four more wires in the box (all corresponding), all in the same color, two each coming into the box from the same direction.
7. The pairs of wires are placed next to each other in the switch as shown in the graphic above. Push them all in until you can feel or hear the copper wire click into place.
8. Now for the assembly: insert the switch, screw it tight and put on the frame and the rocker (depending on the manufacturer’s instructions).
9. Switch power back on and test switch.

6. Connect the series switch

For independent switching of two lamps with one switch you need a series switch.

1. Make sure that there is no current on the wires (s.o.).
2. Remove the old switch if necessary. remove the rockers, remove the frame, unscrew the switch and pull it out.
3. Use the voltage tester to check each individual wire to make sure that no current is flowing.
4. Pull out the wires a little bit and if necessary shorten them a little bit and strip them again (12 – 15 mm).
5. Protective conductors are always all plugged together with plug-in terminals and placed at the back of the box – likewise the neutral conductors with each other.
6. With the series switch there are three phases in the box – one, in which the current arrives and two which lead to the lamps (also called lamp wire).
7. Insert the incoming phase into the plug contact marked "L" until it clicks into place, insert the two outgoing phases into the two openings with the arrow or the numbers.
8. If it is not clear which of the three phases brings the current, please identify it professionally with the voltage tester.
9. At the end, insert the switch, screw it on, put on the frame and the two rockers (as indicated by the manufacturer).

7. Connect double changeover switch

Two lamps, which can both be switched from two switches, need two double changeover switches.

1. Make sure that no current can be on the wires (s.o.).
2. Old switch(es) if necessary. Remove the rocker(s), take off the frame, unscrew the switch and pull it out.
3. Use the voltage tester to check each wire to make sure no current is actually flowing.
4. Pull out the wires a little bit and if necessary shorten them a little bit and strip them again (12 – 15 mm).
5. Protective conductors are always all connected together with plug-in terminals and placed at the back of the box – likewise the neutral conductors are connected to each other.
6. In the socket you will find two phases (incoming and outgoing) as well as four corresponding phases.
7. Double toggle switches are basically like two toggle switches side by side – implemented in a switch with two rockers.
8. Now carefully plug in the cables as shown in the diagram above until they click into place. It is very important that only all plug contacts marked with "1" in the drawing above are connected to each other through both switches and also only all contacts marked with "2" are connected to each other. If you are not able to proceed according to the above diagram without any doubts, because you are not able to assign the cables exactly, then you should leave this to a specialized company in any case.
9. Now insert the switches, screw them tight and put on the frame and the rockers (depending on the manufacturer’s instructions).
10. Switch power back on and test switch.

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8. Frequently asked questions (FAQ)

8.1. Connect light switch – 4 cables?

Presumably this is a socket for a Cross switch or double throw switch. If there is only one lamp in the room and three or more switches, it is the socket for a cross switch.

At two lamps and two switches it is probably a socket for a double changeover switch. It is best to ask or look at the blueprint if available.

8.2. Connect double light switch?

Here we are dealing with a Series switch or a double throw switch, if it is a pure light switch (more s.o.).

Sometimes a Switch with two rockers also for light and for example for an electrically operated roller shutter.

8.3. Switch occupancy?

How to connect which switch correctly is shown in the descriptions and diagrams above.

In case of doubt, it is best to leave the electrical installation to a professional.

8.4. The voltage is on and the lamp is technically working properly – but the light still doesn’t work. What can I do in this case?

Imagine the following case: In a room in your home there are a wall lamp and a ceiling lamp, both of which are supplied with power via the operation of a light switch.

You put one bulb in the lamp and one bulb in the luminaire, but the lamp and the luminaire are not working properly on actuation of the corresponding light switches nothing happens – and neither the light works nor the lamp burns.

We will now tell you exactly what to do in such a case and give you the necessary tips to successfully solve this problem.

As a first step, you should check conductors, whether they carry voltage at all. The best way to do this is to use a Contactless voltage tester . To do this, hold the device to the appropriate conductors. If the voltage test is positive, i.e. lamp, luminaire and the two bulbs have voltage, then there is possibly a defect of lamp and/or luminaire in front of.

You could, however, with the help of a two-pole voltage tester get a more adept result regarding the presence of voltage and thus check the lamp/luminaire for voltage simultaneously. With this procedure the defect of a lamp can be excluded better, than with the use of a single-pole voltage tester.

If you do not have such a device yet, you can use the Price comparison function from do-it-yourselfer.look for a contactless voltage tester or a two-pole voltage tester of your choice.

Please also have a look at our article Voltage tester comparison 2020. There you will find all relevant information, that you need to know in order to select a suitable, inexpensive model for your purposes.

8.5. I assumed a defect and bought a new lamp/and or fixture – but the light still doesn’t work. What options do I have now??

Does not work, does not exist? Unfortunately, this is not always true: If you have not been able to achieve success with our tips, you should rather consult a professional for your own safety.

If even after replacing the relevant devices still can not be successfully switched on, good advice is expensive.

In such a case, please seek the advice of an electrician. Acting on your own can have serious health consequences under certain circumstances.

There seems to be a deep electronic problem in your case, which you can solve with simple DIY skills not be able to solve the problem independently.

The problem will probably be found in the installed power cables and from these non-electricians should better keep their hands off.

Because what do you do, for example, if blue and red cables suddenly come out of the wall when you replace the lamp? And there is no sign of a green-yellow protective earth conductor far and wide?

As you can see, dealing with the electrical system is a highly sensitive process that is better left to appropriately qualified professionals. Especially with the cables you can quickly make fire-hazardous mistakes.

8.6. In my bedroom, there is a ceiling light that is switched by an alternating circuit. Can I use a relay to replace a permanently inaccessible switch?

If your second light switch in the room is permanently covered by a bed, for example, you’ll have to come up with something to make the switch work anyway.

Tip: One possibility would be to use a changeover circuit via relay.

8.7. But what is a relay anyway?

A relay is a switch that is operated by electric current and usually has two switching positions.

Imagine that you are in a huge stairwell full of light bulbs and light switches.

you would have to switch them on and off individually each time, covering vast amounts of steps every day. That sounds pretty exhausting, doesn’t it?

A simple solution for this problem would be to use a relay. By using one you must operate only one light switch, to light up the whole staircase or to put it in darkness.

A Thus, a relay is a device that is used to switch circuits on, off, and over. This is a very simplified, layman-friendly explanation that has been incorporated into the text, as not everyone may be familiar with the terminology.

8.8. And what do I need to consider if I intend to connect a relay?

As soon as the planned scope and details of your construction measures have been determined, you should clarify whether they are at all permissible are. Especially in the electrical field there are strict guidelines. It is best to contact an electrician you trust o.a. The expert can then get an exact picture of the matter and talk you through the circuit diagram at hand, for example.

Depending on the circumstances of your case, it can sometimes be difficult be to solve the problem via a manual from the Internet. If you are not on safe feet in the electrical field, you better turn to an accordingly qualified experts.

Even though we clearly recommend that you consult an expert, here are a few things that you should definitely keep in mind. You should clarify, whether the relay you bought is approved for the intended purpose at all – again, it is best to ask an expert for advice.

Hint: If you want to connect a relay with a smaller voltage, the overall picture of the project is nevertheless crucial, whether the thing is at all permissible.

8.9. Is there also another option to solve the problem with the changeover switch?

Even though the installation of a relay is a common solution for such cases, there is still other possibilities, to approach the matter. You could use a Use a radio switch – what would possibly be a cheaper and more efficient alternative. A radio switch, which you can stick on and is operated without battery is possibly the Much simpler solution for your problem.

About the Price comparison function from do-it-yourselfer.de you can start looking for a cheap device and then buy it, no matter if you are looking for a relay or a radio switch. On our site you will also find numerous other articles on the subject of electrics.

Image credits: Adobe Stock/Patpitchaya, Adobe Stock/Marc Stock, VGL/Christiane Baldwin (graphics), Adobe Stock/magele-picture, Adobe Stock/Nivellen77 (chronological resp. sorted according to the order of the pictures used in the buying guide)

As an online re-designer, I combine my DIY passion with my profession – in home office and workshop. I like to use my ex-per-ti-se in building- and tinkering-themes to advise our le-se-r-ners as good as possible.