How to install a single key light switch - wiring diagrams
One-key light switch is the most common household switching device. It performs a simple function - it closes and opens the power circuit of the light bulb. Once you understand its structure and the basic principles of attachment, the connection of the single switch is not difficult to do yourself.
Types of single-switch switches
At the inexperienced view the answer to this question is not difficult - a single-key switch contains one key that controls the switching on and off of lighting. With a little in-depth study of the subject, it turns out that there are several types of appliances with one movable constructive element. The three most common are:
- the conventional fixture;
- through;
- cross-over.
They differ in the device of the contact group. The loop-through, as well as the cross-over fixture are designed for use in complex systems - for independent control of lighting from different points. Externally, it is almost impossible to distinguish them from the front, the markings are not always applied. From the back they can be differentiated by the number of terminals and by the switching scheme, which is often applied on the back side. That's why you have to be careful when buying.
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When you study the principle of operation of through and cross apparatuses, it becomes clear that for the usual switching of lights (on-off), you can connect them, if they are accidentally purchased or others are not at hand. But such devices are more expensive. And the standard wiring diagram of an ordinary single switch is shown in the figure.
There are two types of single-switch devices:
- overhead;
- internal.
Functionally, they are the same, but the first is mounted on the surface, and the second - in a specially equipped recess.
The device of the switch with one button
From the outside, the single-switch device is seen as a movable part and a decorative frame. Both parts are easy to remove.
After removing the key, you can see the sliding panel associated with the contact group, the terminal screws, and the release lug screws. If you remove the frame, you can see the screws fixing the device to the wall. You can also see the power indicator, if installed.
With further disassembly you can get to the contact group, which consists of moving and fixed contacts. Sometimes the terminal screws are on the back. If they are located on the front, there is nothing interesting on the back.
Hereinafter under the single-key switches will mean other switching devices with a single contact group for making and breaking: rotary design or with a button.
Preparatory work and choice of installation location
Installation of a single-switch begins with the selection of the location of the switch itself, the junction box and the lamp. Refer to the diagram above.
In practice it is realized as follows:
- A cable from a fuse box in the switchboard with L, N, PE conductors (in the TN-C system there may be no protective conductor) goes to the switchboard;
- The same cable goes to the lighting fixture;
- A two-core cable is inserted in the phase conductor gap to connect the switch.
Important! There is an opinion that a three-conductor cable should also be laid to connect the switch. One conductor will not be used, but it may be useful when upgrading the system in the future (installation of a pass-through or reversing apparatus).
It is very desirable for the first two points to use cable products with color or digital core markings. This reduces labor costs when unplugging (no need to wire and mark the cores) and minimizes the likelihood of error. And marking is not required for the cable that goes to the switchgear. Wiring is independent of phasing.
Usually for lighting installations cable with copper conductors with a cross section of 1.5 mm². Cables suitable for installation can be selected from the table.
| Cable | Number of wires | Additional features |
| VVGp 2x1,5 | 2 | Flat |
| VVGp - NG 2x1,5 | 2 | Flat, non-combustible |
| VVG 3h1,5 | 3 | |
| NYY-J 3x1,5 | 3 | Non-combustible |
| VVG-NG-Ls 3х1,5 | 3 | Non-combustible with low smoke emission |
Rules for Electrical Installation Installation places for household switches are not strictly regulated. Precisely specified only the distance to the gas pipes. It must be at least 0.5 m. It is recommended only to install the devices at a height of 1 m. An exception - children's institutions. There, the switching elements must be installed out of reach of children - 1.8 m, and on this point the rules are strict. For the rest, you can be guided by the principles of safety and convenience. It is also necessary to determine the type of wiring (concealed or open) and when choosing the place of installation of the device and switchboard, consider the convenience and possibility of laying cable products.
The order of installation of electrical appliances (step by step instructions)
If you have chosen a hidden wiring, it is necessary to equip recesses in the walls to install switchboard and subrocket (plastic box, in a similar box installed and the socket). If it is open, you must mount pads (platforms) on which the devices will be installed. Then it is necessary to lay the cables in the chosen way, put them in the socket and junction box. After that you can proceed to installation. The minimum set of tools that you will need for this:
- wire cutters to shorten the wires;
- A wire cutter to remove the insulation;
- if available - wire stripper for stripping wires;
- a screwdriver set (at least two).
You may need something else in the process.
First, the cable must be shortened to a length at which it will be possible to close the junction box or install the device in a socket after installation.
First, you must remove the outer sheath of the cable with a cutter knife. It should be done carefully so as not to damage the insulation of the conductors (especially not to touch the copper cores).
Next, you must strip conductors of insulation to a length of 1-1.5 cm. This is also done with a wire cutter, and if there is an insulation remover, it is even more convenient to work with it.
The stripped ends are bent in the right direction. After that, you can begin to unplug. Traditionally, connections in boxes are made by twisting. You can do this now, observing two rules:
- Copper and aluminum conductors should not be stranded;
- All stranding must be insulated (with insulating tape or plastic caps).
It is advisable to solder the copper strands before insulating them.
But in today's environment there are more convenient ways to connect conductors in a box. Various types of terminals are available on the market for electrical wiring - both screw-type and clamp-type terminals.
The installation is cleaner, safer and more reliable.
Next, you can proceed to connect the switch itself. The first steps are similar:
- shorten the two-core cable;
- Remove the outer sheath;
- Strip the insulation of the wires.
Then the device must be disassembled - carefully so as not to break, remove the key and decorative panel.
The next step is to insert the stripped ends of the conductive cores into the switch, fix them. The order of connection does not matter, but usually the supply end is led to the bottom terminal, the outgoing end to the top terminal.
Next, the switch is installed back in the box, unfasten the petals, fasten to the surface with self-tapping screws.
After completing the connection of wires, it is necessary once again to check the correctness of the mounted circuit. Lastly, the decorative frame with the button is installed.
This completes the connection of the electric light switch with a single button. You can apply voltage, then check the operation of the light.
Safety rules for installation
The basic safety rule is that all work must be carried out with the voltage off. The absence of voltage in the workplace must be guaranteed. One hundred percent certainty is provided by the production of technical measures:
- Disconnecting the voltage in the switchboard by disconnecting the appropriate circuit breaker;
- Disconnecting the outgoing conductor from the circuit breaker - this creates a visible break in the circuit and will prevent erroneous voltage supply by unauthorized persons;
- Checking for absence of voltage (with a screwdriver, multimeter) directly at the workplace - because of errors in marking or lack of up-to-date changes in the switchboard circuit diagram, the wrong circuit breaker or circuit breaker can be tripped.
Important! Safety rules for working in electrical installations also require the earthing of live parts, as well as the hanging of warning and protective placards. It's hard to imagine that anyone doing housework will adhere to these rules. But safety precautions are never insufficient - it is advisable to heed these points.
Protective equipment is also an important part of safety when working with electrical appliances:
- dielectric gloves;
- dielectric mats;
- Insulated hand tools with an undamaged, unworn coating.
Also helpful to read: Wiring a circuit breaker with a single screwdriver.
And most importantly, remember that an energized conductor looks exactly the same as a de-energized one. The de-energized wire must be monitored with instruments.