Connecting a light switch with two keys: the nuances of installation work

Amir Gumarov
Checked by a specialist: Amir Gumarov
Author: Marina Sturova
Last update: March 2019

Two-key switches are used, if necessary, to control two electric lighting devices simultaneously from one point. They also help to adjust the brightness of the light in the simplest way. Agree, connecting a light switch with two keys creates additional convenience.

We suggest that you familiarize yourself with the detailed installation process and installation of a double switch. Here you will find interesting information about the device design features of the light control. With our help, you can easily carry out installation.

We thoroughly described the briefing with visual illustrations, photo selections, wiring diagrams and a video guide.

Internal device breaker

The internal device of a two-phase switch differs from a single-phase switch by the presence of two output terminals instead of one.

More specifically, it consists of the following elements:

  • mechanism and decorative panel;
  • one input terminal;
  • two output terminals;
  • two keys.

Terminals are special clamping mechanisms. To connect the wire, you just need to strip it, insert it into the terminal strip and tighten it with the screw. The input or common terminal is predominantly separate and is labeled L.

On the opposite side are two output terminals. They can be designated as L1, L2 or 1,2. Some models may have screw terminals instead of a terminal block. It is undesirable to use them, since the fastening may gradually weaken and it will have to be tightened.

Two-key switch
The main difference between a two-key switch and a single-key counterpart is that it controls the pair of lighting fixtures

Install the device so that when it is turned on, press the upper half of the key. You can determine the top and bottom of an element using an indicator - a special screwdriver that works to close.

To do this, take a nail or a piece of wire and touch it to one contact, apply an indicator to the other, holding the thumb on top.

Switch device
The device of the switch with two keys is slightly different from the one-key. The main components of the device: mechanism, keys and decorative case

If the light inside does not light, then the switch contacts are open. When the keys are on, it should light up. It remains to mark the top of the element.

Step-by-step process description

In addition to standard models, the two-key switch can be additionally equipped with a backlight, indicator. The backlight helps to determine it in the dark, and a glowing indicator will make it clear that the electrical network is working and is closed. They also produce models with shockproof and moisture proof housings. They can be installed in a bathhouse, bathroom or on the street.

There are also breakers. They have almost the same design, with the exception of an additional terminal. Such devices are connected to one or a group of fixtures and allow you to control lighting from opposite ends of the room. For example, going into the bedroom, you can turn on the light, and going to bed, turn it off near the bed.

In practice, wiring accessories with one caliper and two keys or two single-key modules connected by a jumper can be used as a two-key device for controlling a lighting device. The difference in their installation is represented by the following photo selection:

# 1: Features of choosing a place to install

There are no standards for the placement of the device by law. Their installation implies convenient use for adults and children.

And if earlier it was common practice to place the device at a height of about 2 m, now the switch is often located at the level of the lowered hand of an adult.Thus, the element becomes available to almost all residents of the house.

Two-gang switch
It’s better to place the switch so that it is accessible to everyone except the smallest

The only place where the placement of the switch can have any restrictions is a bathroom or a bathhouse. Here you need to consider the placement of the washbasin and the open shower. When using the device, it must not fall under water droplets.

# 2: Preparing for installation

Whatever electrical work you have to do, the first thing that is important to do is turn off the power to the network. Not for a second should we forget that electricity is dangerous. In addition to the effects of current, poorly wired electrical wiring can cause damage to electrical appliances or a fire in the house.

Rules of conduct when working with electric networks:

  • be sure to disconnect the network;
  • Do not touch connected devices with wet hands;
  • Do not use metal brackets to secure the wiring;
  • Do not overload the electric network;
  • it is better to replace the damaged wire with a new one, and not repair it;
  • work can only be done with a tool with insulated handles;

When working with electricity, do not touch water or gas metal pipes.

Starting to self-connect, you must:

  • take safety precautions;
  • familiarize yourself with the laws of wire marking;
  • Check the network for labeling.

To any landlord for replacement and switch connection hardly want to invite an electrician. In addition, to perform this task, there is no need for sophisticated instruments and tools.

To install you will need:

  • mounting knife;
  • insulation tape;
  • hammer and chisel;
  • pliers;
  • indicator screwdriver, as well as curly and straight.

If the installation has to be carried out in a new place, and the house has hidden wiring, a drill with a “crown” nozzle or a perforator may come in handy.

Indicator screwdriver
Not a single electric installation work without a screwdriver indicator

# 3: Definition of electrical wires by color marking

Without knowledge and adherence to the marking, installation is strictly prohibited. It is used to create a safe environment and reduce time spent on work.

Correct Conductor Labeling
Correct labeling from the manufacturer will help to avoid problems with the identification of conductors

To form the correct compounds, the following notation is used:

  • zero - always and without exception, blue;
  • protection is also strictly the same color - yellow-green;
  • phase - is predominantly brown or red.

These are just the basic combinations. In addition, to avoid confusion in identification, use alphanumeric marking.

If during the work it became clear that there are no visual signs, it is necessary to independently mark the wiring using a multi-colored heat shrink tube or color insulation.

# 4: Identification of conductors with a multimeter

Blindly trust marking is not worth it. These designations have repeatedly changed their standards. Therefore, getting down to business, it is necessary to additionally check the nature of the conductors. To do this, use an indicator screwdriver and a multimeter.

If a single-phase electric network without a grounding system is carried out in the building, then an indicator will help to determine the phase or zero. Having disconnected the electric power, they clean the conductors and take them away so that they do not touch each other.

Turning on the power supply, bring a screwdriver to the wires. The lamp in the indicator will flash, when you touch the phase conductor, and from touching zero it will not light up.

Multimeter
Multimeter - a multifunctional control and measuring device that performs the work of at least three control devices: voltmeter, ohmmeter and ammeter

To analyze a network in which there is a third, protective conductor, use a multimeter. Setting the range for alternating current to a value of more than 220 volts, bring one tentacle to the phase, the other is fixed on any of the conductors. Upon contact with a neutral wire, the device will detect a voltage within 220 volts, with a protective one a little lower.

# 5: Removing an old electrical switch

To have access to the fasteners, you need to remove the keys and the decorative panel. To do this, use a screwdriver or a thin knife to pry the first key and carefully remove it. So do the second. Next, remove the decorative cover. In some models they are unscrewed.

Disabling voltage in the shield
The basic safety rule when working with wiring and wiring devices is to disconnect the supply voltage for the period of work

Then the mechanism itself is taken out - it can be attached with clamping feet or screws. Disconnect the conductors and, if necessary, dismantle the old socket.

The process of dismantling is clearly demonstrated in the photo gallery:

# 6: Installation of elements with closed and open wiring

The installation of switches in newly built dwellings boils down to connecting the element to a previously conducted power. In the old house, in which the old wiring already requires replacement, you have to make new shtabs and lay the cable.

And with open placement of electrical wiring, each cable is brought to the switch in insulating corrugated pipes, cable channels.

The subsequent choice of the circuit breaker model and the method of its installation depend on the method of laying wires in the house. A device that is suitable for open wiring consists of a flat socket, an internal mechanism, an insulating decorative cover. The structure does not hide in the recess of the wall, but completely protrudes above the surface.

Two-key switch for open wiring
The device of switches for open and closed wiring differs only in the shape of the socket. For overhead devices, it is a thick plate of dielectric material

Installation begins with mounting a socket - flat bottom. Carry it out using suitable fasteners. For different wall surfaces, screws or dowels, screws, screws can be used.

Further, after connecting the wires, the mechanism of the switch is fixed, a decorative insulating cover is put on. In it, the manufacturer has already thought out a hole for supplying a conductor. The lid itself is put on, hiding the mechanism, and secured with latches.

For dual circuit breaker installation in rooms with hidden wiring use socket boxes (mounting boxes) in the form of a small bowl. A hole is cut out in the wall or a small indentation of the appropriate size is made.

Mounting the circuit breaker
Clamps help to fix the mounting box in the wall reliably: when tightening the screw, they slightly spread out and abut against the wall surface

During installation, make sure that the device locks smoothly, without distortions. Podrozetniki can be installed side by side - any required number - and fixed with plaster mixtures. Then, towards the socket, hollows are hollowed out with a depth sufficient to lay the wire.

Row of rosettes
Podrozetniki have special mounts that help them cling to their "neighbors"

# 7: Options for connecting electrical wires

The weakest links in the electric circuit are places wire connections. Not surprisingly, most malfunctions occur there.

Methods of twisting wires
The simplest in its own way, the method of connecting wires with twists with additional fixation with electrical tape cannot be called reliable. With poor performance, this is the most common cause of open circuit (+)

When connecting a switch, there is no need to consider all connection methods, here are the most basic ones:

  1. Manual twist - A very common method that requires subsequent isolation.
  2. Terminal block - It is widely used as a connecting link. It consists of copper clips clad in a plastic case.
  3. Soldering - Although it helps to create high-quality adhesion, the complexity of the process does not contribute to its popularity.

It should be said about the heat shrink tube, which perfectly helps isolate the joints and even strengthens them a little.

Heat Shrink Insulation
The heat shrink tube is tightly compressed around the wire when heated, creating reliable protection

# 8: Connection diagram and step-by-step actions

With the old system of conducting electrical networks, power is supplied to the house from the electrical panel via a two-wire cable. The ground loop is located on the transformer to which the neutral conductor is connected.

Despite its simplicity, this method has a significant drawback - a low level of security.

Connection diagram for single-phase power system
In the two-gang switch, the phase is connected with one wire, and each lamp is connected to a separate terminal

In the working case of the switch, one of the phase conductors of a three-core cable is connected to a common terminal strip (L). To do this, lead the wire into the terminal hole and tighten the screw. Two other phase electrical wires are connected to separate contacts, and then lead to the mounting box and connected to the phases of the luminaires.

Chandelier Connection Diagram
When connecting a multi-tube chandelier to a two-gang switch, the lamps are divided into two groups

The wiring connection must be in a junction box. It hides sloppy weaves from sight and serves as an insulator.

To properly connect the electrical wires, do the following:

  1. Conductors coming from the fixtures and a two-phase switch, as well as the power supply cable, are put into a box, remove the insulation coating from a 2-3 cm section.
  2. Connect the phases of the main power cable and the switch.
  3. The incoming neutral wire is connected to the neutral wires of the fixtures.
  4. The phases extending from the switch are alternately connected to the phase conductors coming from the lighting fixtures.

Only a phase wire is led to the switch. It is strictly forbidden to connect it to a neutral wire. Otherwise, the ordinary replacement of a light bulb can be a dangerous procedure.

Any wire is better to fail with a margin, laying the excess behind the structure. It is not permissible to leave open wires, even inside the elements. All exposed areas must be carefully insulated. Do it better with textile tape.

You can find common circuits for connecting a double switch in popular article our site.

Connection example from a nearby outlet

Consider the option of connecting a control device for two lamps according to the scheme below:

Connection diagram of the switch from the outlet
Scheme for connecting a switch that controls two lamps from a nearby outlet

The location near the outlet and switch is a common situation for small domestic apartments. Let's figure out how to connect a double switch in this case:

Installing a two-phase breaker

To control several lighting fixtures from different ends of the room, use switch with two keys. In its internal structure, it looks like two single-key walk-throughs, combined in a common decorative case. It contains two groups of terminals that open the current supply from one pair of electrical wires to another.

Two-key switch wiring diagram
When making a loop-through connection, it is important not to confuse the pairs of conductors so that both switches close the contacts of one of the two electrical circuits

How to install:

  1. The phase conductor from the mounting box is laid to the terminals 1 and 2 (right), which are interconnected according to the scheme.
  2. Four phases are already leaving the switch, which lead to the box, and then to the second switch.
  3. Two phases depart from switch No. 2 (without intersecting). They lead to the box, where they are connected to two independent conductors leading to the lamps.

Carrying out the installation, you can first carry out one pair of wires, and then the second, so as not to confuse them, otherwise the circuit will not work.

Connection to the power supply system

It is possible to determine that the electrical wiring is carried out according to the new system through the laid cable. It will be three-core with single-phase power or five-core with three-phase power. One of the single-phase supply wires will be the phase marked in brown or red, the other is neutral (zero) marked in blue, and the third will be the protective conductor marked in yellow-green.

To facilitate identification, use alphanumeric designations:

  • A, B, C - phase;
  • N is neutral or zero;
  • PE - protective.

Difference of this wiring diagrams consists in an additional protective conductor PE, which is led directly to the fixtures.

Connection diagram with the new TN-S system
The wiring diagram for TN-S wiring accessories involves connecting to a grounding system

After attaching the wires to the working mechanism, they are drawn closer to the case, and then installed in the socket. Fasten in mounting box with clamping feet or bolts. Put on a decorative case and keys.

Connection to the switch with two keys of the lighting device
Before assembling the entire structure, turn on the light and make sure that the lighting system is working

Conclusions and useful video on the topic

You can watch the available video on installing a simple electrical circuit here:

When installing the electrical network or its elements, it is necessary to correctly follow the above instructions. If there are doubts about how to properly connect the light switch with two keys to the network, it is better to contact a professional.

If you have interesting information about the installation of a double switch or if you have found controversial issues in the article, please write comments. For commenting below is a block form.

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Visitors Comments
  1. The electrician of me is unimportant. I once tried to install the switch itself for a new chandelier. According to my idea, with one key turned on, one light bulb should be on, and when you turn on the second, all the others. But as I did not try, either nothing at all burned for me, or everything burned at once with any key turned on. He decided not to mess with this anymore, after all, an electrician is a dangerous business.

    • Expert
      Amir Gumarov
      Expert

      Good afternoon, Ivan. I recommend to draw a diagram before starting installation work. The logic of its operation in relation to your chandelier comes down to splitting the phase in the switch into two lines - one goes to the first group of bulbs, the second to the remaining. The zero wire that comes from the junction box must be divided into groups within the chandelier itself. Attached a diagram to make it clearer.

      Attached photos:
  2. Vladimir

    I myself set and connected the light switch with two keys. From my own experience, I can confidently say that if you do not understand electrical installation at all, it is better not to show initiative. At first glance, the connection diagram is very simple, but in fact there are a lot of nuances, and in order not to make things worse, it is better not to save and call an electrician.

  3. Ruslan

    Generally speaking, installing a circuit breaker is not something so supernatural. However, I once had a case, when installing it happened by chance that the bare wire touched the skeleton of the switch. Because of what, electricity passed freely through it (I decided to check the operability before installing the plastic case). If it weren’t for the indicator screwdriver, I would have been thoroughly beaten by the current. And all because I just gave a little extra when stripping wires. So be careful when installing even such a simple thing.

  4. Semen

    How tired of these monotonous articles with stolen content from other sites - finally write the author’s material .. stop stealing information from other sites and broadcast on different sites.

    For an hour now I’ve been looking for something worthwhile about the switches, and after the first positions of the search - everything is the same licked from them ... SHAME!

    • Expert
      Amir Gumarov
      Expert

      Hello. Articles on the site undergo strict uniqueness control and are written by professionals in various fields. Unfortunately, content and even forum questions are constantly being “licked” from our site. Write what exactly interests you about switches and we will give you a clear answer from a regular electrician.

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