Connecting a double switch: standards and diagrams + installation instruction

Amir Gumarov
Checked by a specialist: Amir Gumarov
Author: Tatyana Zakharova
Last update: May 2019

Convenient two-key switches due to the increase in functional load outperform single-key counterparts. If instead of ordinary single wiring devices to equip the house with double appliances, the savings will be significant.

The connection of the double switch should be in compliance with safety standards and regulations.

In this material we will tell you how the double switch is arranged, name the advantages of such devices, and also give detailed instructions for installation and connection.

How is a double switch arranged?

No device can be connected correctly without first studying its “filling” and the principle of operation. In this sense, circuit breakers are not particularly difficult.

The device of two-key models repeats the design of single-keys, but differs in the number of terminals and the connection principle. The external difference is reflected in the name of the model - it has two separate keys, each of which controls the electrical circuit.

Dual circuit breaker
The switch can be divided into two parts: external and internal. The first consists of a decorative frame and keys - the main tool for managing light sources. They simultaneously protect work items. The second is an internal mechanism with terminals

In the manufacture of devices using metal and plastic parts. In particular, conductive metals such as steel and copper are used for contacts.

To better consider the individual elements of the switch, we will figure out how it happens disassembly and connection.

Symbols for which numbers and latin letters are used may differ on different models. For example, L may indicate the total supply phase, while the numbers 1.2 are the outgoing phases. Also, arrows can be used to indicate input / output.

The advantages of two-key models

What is it worth to abandon the familiar and simple single-key devices in the device for the sake of double?

In fact, the benefits are obvious:

  • from one device you can control two different lighting devices or two groups of lamps;
  • the light intensity in the room can be adjusted, depending on the number of involved light sources;
  • due to the selective inclusion of individual fixtures, energy is saved;
  • if desired, you can control the lighting mode in two rooms at once (in the kitchen and corridor, in the bathroom and toilet);
  • more rationally and economically consumed electric wires.

Adjusting the light is the ability to create a comfortable environment for performing certain actions. For example, to work or read, you can use both keys to turn on all 5-6 lamps of the chandelier. And for relaxation, 1-2 bulbs are enough to create diffused, dim lighting.

Another advantage of modern models is a different design. Due to the color and style diversity, you can choose a device that looks the most suitable for the decoration of the room.

Like single keys, dual models are built-in and overhead. If the walls in the apartment / house are made of brick, concrete, aerated concrete or drywall, internal switches are usually installed.

Installation of overhead devices is typical for wooden houses, where during the installation of internal wiring, certain difficulties associated with the rules of PUE are expected.

Popular circuit solutions

When choosing a double circuit breaker connection scheme, two related factors should be considered:

  • which grounding system is used in the house - TN-C or TN-S;
  • one or two lighting fixtures controls the switch.

TN-C is considered an obsolete grounding system. A feature of mounting a switch is that it receives only two wires from the switchboard instead of three.

Two-key wiring diagram
If you connect two lights to one switch, it will look like this. Please note that the neutral wire (blue) combines the ground and zero. So the third wire is not needed

The houses of the new buildings use the modern TN-S system. Before you connect a double switch yourself, you must make sure that a three-wire wire is drawn from the machine to the place of attachment of the electrical installation.

Compare the difference in connection.

Three-wire circuit
The circuit is characterized in that three conductors, including earth, are stretched from the electrical panel to the junction box. Accordingly, earth is also supplied to each lamp / group of lamps

The presence of a third grounding conductor does not affect the connection of wires in the circuit breaker mechanism: only phase wires, one input and two output, still remain there.

If the lighting devices controlled from one switch are in different rooms, the circuit will differ only in the dilution of the conductors in different directions. Consider the scheme in which one group of lamps is in the room, the second in the corridor.

Scheme for connecting two groups of fixtures
Laying the wires from the electrical panel and the switch, as well as connecting the wires in the distribution box, occurs according to a similar scheme, but then the wires diverge in different directions

If the machine is connected by a three-wire wire, then the earth joins the grounding conductors of the groups of fixtures and, like zero, is bred in two directions.

Chandelier Connection Diagram
Connecting the chandelier to two keys of one switch facilitates installation only by the fact that instead of two wires you have to pull one - from the switch to the chandelier

The appearance of the third grounding conductor does not fundamentally change the circuit: it moves away from the circuit breaker in the panel and in the distribution box it is connected to the ground of two groups of lamps.

The distribution of lamps of one chandelier into groups can occur in different ways, depending on the requirements for lighting intensity. The five-arm device can be divided in two ways: 4 + 1, 2 + 3.

The number of options for connecting a six-arm chandelier increases: 1 + 5, 2 + 4, 3 + 3. That is, the more lamps in the lighting device, the more options for combining them into groups.

Installation and Connection Instructions

The connection process can last up to 15 minutes, if a simple replacement of the old device is required, or several days if it becomes necessary to lay new wiring.

Material selection and tool preparation

If the house / apartment is being renovated, they try to replace the old aluminum wires with copper wires, which surpass them in all respects. This is regulated by the rules of the PUE.

Installation Requirements
When choosing a mounting location, do not forget about the recommendations of the PUE: height from the floor - 60-180 cm, distance to the gas pipeline - 50 cm, distance from the doorpost - 15-20 cm

Wires must be laid either horizontally under the ceiling, or strictly vertically down to the installation site. This will prevent accidental cable breakage during subsequent repairs.

To work with electrical installations, you will need a hand tool with insulated handles:

  • universal screwdriver;
  • round pliers;
  • pliers;
  • construction or office knife;
  • indicator screwdriver.

Marking material and protective gloves with insulation are also useful.

Grooving a grooving cutter
If you have to wall the wall, then in advance you need to worry about the presence of a wall cutter, perforator or drill, as well as a plaster or mortar for puttying the walls

The switch is chosen, focusing on interior design. When buying a new cable, the system load is taken into account. Lighting groups belong to the most low-power sections of the network, therefore, VVG cable 1.5 mm², and preferably VVGNG, with low-flammability polymer protection, is suitable.

Cable counting is done using a tape measure. To the total length of the wires you need to add a margin for twisting in the distribution boxes and mounting in the terminals. Read more about calculating the cable cross-section in this stuff.

About the connection of electrical wires in the distribution box

The first stage is connecting the cable to the machine, which is located in the switchboard:

  • working core (red or brown) - to the terminal of the circuit breaker;
  • zero (syn.) - to the zero bus;
  • grounding (green or yellow-green) - to the grounding bus.

It is recommended that the work with automatic devices located on the switchboard be delegated to electricians who are responsible for the state of the communal building network. It is forbidden to make any changes to the switchboard yourself. We also recommend reading an article where we examined in detail the color marking of electrical wires. More details - go to the link.

From the panel, the wire is pulled to the junction box, and from it to the switch and the lighting device or to two devices / groups. It is very important not to confuse wire connection in the distribution box.

Junction box wires
The conductors are connected as follows: phase of the machine + incoming phase of the switch; 2 outgoing phases of the switch to each of the two phases of the fixtures; zero from the shield + 2 zero lamps; ground from the shield + 2 lands of fixtures

As a result, five connections must be made in the electrical box. To do this, use twisting, soldering or a more modern method - terminal boxes.

Wall Mounting Procedure

The switch is mounted in two ways: in a special installation box (socket box) or directly into the wall. The second method is preferable if the device is mounted in a drywall partition. Consider a step-by-step instruction on how to connect and install a double switch on your own.

Before installing the DV, it is necessary to connect all the lighting devices from the working circuit: one chandelier, a chandelier with a group of spotlights or lamps in different rooms. Without the initial installation of the fixtures, it is impossible to correctly verify the operation of the switch.

It is possible that the lights do not light up. You will have to disassemble the switch again and make sure that the wires are inserted into the correct terminals. The reason may lie in the improper connection of wires in the distribution box - you have to look into it.

A detailed wiring diagram for the two-gang switch is described in this article.

To make it easier to determine the working function of each wire in the future, even during installation, the cores are marked.

Do not forget about security

Any manipulations with electrical installations should begin with turning off the machine, which is located on the dashboard. After that, the presence of voltage in the network is checked again with an indicator screwdriver or a tester - and so every time before you start working with wires.

If the shield is located on the landing, then it is recommended to hang a warning sign for the duration of work so that someone does not accidentally turn the switch.

Electrical work in pairs
If you begin to comprehend the basics of wiring, do not work alone, but be sure to invite a partner for insurance: he will hold a stepladder and give it a pair of pliers

Protective gloves with insulation can also protect against electric shock, although it is not very convenient to work with wires in them. During wall chiselling and puttying it is better to use work clothes, comfortable shoes and a mask or respirator to protect the lungs from dust.

Conclusions and useful video on the topic

Interesting information about how to connect wires, install a switch, connect devices will add to your knowledge of home wiring.

Nuances of connecting a backlit electrical appliance:

Details on the connection of wires in the distribution box:

Connecting a chandelier using soldering:

From choosing a place to connecting to the machine:

Having experience working with electrical wiring, you can easily cope with the installation of a two-key switch - the main thing is not to make a mistake with the choice of circuit and stretch reliable wires. However, in case of doubt regarding the connection or connection of cores, it is better to seek the help of a professional electrician or to carry out all actions under his control.

Do you have practical skills for connecting two-gang switches? Or have questions about the topic of the article? Please ask them in the comments box, and we will try to respond to them promptly.

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Visitors Comments
  1. Dmitry

    At installation of switches, and two-gang including including, it is possible to avoid use of distribution boxes. According to the PUE, the distribution box should be accessible for maintenance, and in the conditions of modern repair this is not so easy to do. We do it easier, in the socket box to the switch we bring all the same wires as in the switch box, and we perform the wiring directly in the socket box behind the switch mechanism. And the wolves are full, and the sheep are safe!

    • Expert
      Amir Gumarov

      Good afternoon, Dmitry. A modern repair that makes repackages inaccessible is nonsense. No one forces bricking junction boxes into the thickness of the plaster. Install them so that the covers are flush with the finish - you need to open them, cut the wallpaper crosswise and open the cover. I attached a photo of such an opened box. The finish, as you see, was not broken.

      The generally accepted subceiling trunk electrical wiring allows you to quickly mount additional boxes, make branches for additional lighting fixtures, sockets.

      Attached photos: