How to properly install and wire a dual switch
The switch with two buttons is a widespread household electrical device. Its design, application, the order of installation - the subject of this review. After studying the proposed materials, the home handyman will be able to perform all the preparatory work and connect yourself a double switch for 2 light bulbs.
Device device with two keys
Corresponding to the name, the two-key device from the front looks like an electric device, on the front panel of which there are two plastic buttons enclosed in a decorative frame. If the plastic parts are removed, you can see two movable panels that actuate the contacts.
If you continue disassembling the unit further, you can see the contact group and a visual diagram of its connection.
The wiring diagram of the twin consists of two switches. Their inputs are combined and brought out to a common terminal.
These terminals can be seen on the back of the device:
- common (it is often designated by the letter L, in the same way in many cases the wire that is connected to this terminal is labeled);
- Two outgoing terminals (L1 and L2) respectively, these terminals are equivalent and are each controlled by their own key.
Some devices are equipped with a chain for backlighting. It is performed on the basis of an LED or neon lamp.
In most cases, the illumination circuit is put only on one pair of contacts. This should be taken into account, for example, when searching causes of blinking of LED lights..
Wiring diagrams
There are three main ways of using a two-pin switch:
- Switching on two different lighting fixtures in different rooms or areas;
- Switching two different lighting systems in one room;
- control of lamps or groups of lamps in multi-arm chandeliers.
In principle, the connection diagram of the two-key switch in both cases will be the same, but the wiring will be different.
In the first two cases, a copper cable is laid to each luminaire, containing conductors:
- phase (L), marked in red in the figure;
- neutral (N) - blue;
- protective (PE) - yellow-green.
Important! If the TN-S or TN-C-S lighting system uses incandescent lamps, the PE conductor on the consumer side is not connected (there is nowhere to connect it), but laying this conductor is necessary. In case the lights are replaced in the future.
You will also need a three-core cable from the switchboard to the box and a three-core cable to connect the two-button device.
For a single chandelier with two groups of lamps, the following copper cable products will be required:
- three-core cable from the switchboard to the junction box (two-core if there is no PE conductor);
- four-core cable from the box to the light fixture (three-core in TN-C system);
- three-conductor cable from the box to the switch (regardless of the presence of protective earthing).
It is recommended to use cables with color-coded insulation or numbered cores. It is desirable to use a cable without a conductor with yellow-green insulation to connect the switch, so as not to mislead repairmen in the future.
Installation instructions
Installing a switch As part of the lighting system consists of several stages. Each stage should be considered in detail.
Selecting and installing the circuit breaker
Any lighting network, regardless of the design of the switching device and the number of keys, must be connected to the switchgear through a circuit breaker. It acts as a reusable fuse - disconnects the protected area (conductors and load) in case of overload or short-circuit. The question of the principles of choosing the rating of a circuit breaker is beyond the scope of the review, so it is only worth mentioning that for a network made of copper conductor products, the protective device should be:
- With a rated current of 10 A;
- with a characteristic B or C (in the first case the device will have higher sensitivity and lower tripping time at overload).
In this case, the circuit breaker will work with a load up to 2200 W, which is enough to power any reasonable lighting network (especially taking into account the general transition to LEDs). If the load allows, you can also supply a 6 amp circuit breaker. In this case, the selectivity will be guaranteed - in case of a short circuit on one outgoing line, only its own device and not the common (group) one will be disconnected, and the other serviceable lines will remain in operation. But the feeder load must not exceed 1200 W.
If the case is non-standard and an increased cable cross section is used, the rated current of the automatic unit can be selected from the table.
| Cross-section of conductor, sq.mm | Field of application | Rated current of circuit breaker, A |
| 1,5 | Lighting, instrumentation circuits | Circuit breaker rated current 6 or 10 |
| 2,0 | Outlets, dedicated line for heavy loads up to 3500 kW | 16 |
| 4 | Single power consumers (washing machines, ovens, etc.) | 25 |
| 6 | Electric stoves, electric boilers | 32 |
| 10 | Electric cookers and electric boilers Electrical bushings to apartments and houses | 40 |
Once you have selected and purchased a circuit breaker, it must be installed in the switchboard. Now all other types of installation has superseded installation of electrical appliances on a standard DIN rail.
This method is the most convenient and fastest. The device is snapped onto the rail in one movement.
After installing an apparatus or group of apparatuses, clips are installed on both sides. They do not allow the devices to move along the rail.
The automatic unit is included in the gap of the phase conductor. It is customary to bring the supply end at the top and the outgoing end at the bottom. If you do the opposite, it will work - the electromagnetic and thermal releases of the protective device does not care which way the current goes. But later it will be more difficult to understand the installation.
Important! Do not break the neutral conductor by putting a fuse, circuit breaker or other switching device in it!
Choosing the type of wiring
Now you need to determine the type of wiring: open or closed. The main argument for closed wiring is the aesthetic component. There are also reasons in favor of hiding the wires in the wall:
- minimal risk of damage;
- in the case of a short circuit, there will be no fire - the wires will burn off inside the wall;
- Such wiring will not interfere with future cosmetic repairs.
The main disadvantage is the laboriousness of performing wall reaming and the need for special tools and skills for this, as well as for subsequent sealing. Of the other disadvantages it should be noted difficulties:
- with determining the location of the fault when it occurs;
- Labor-intensive and large amount of work when repairing;
- difficulties in diagnosing the state of the insulation when it naturally ages and leaks appear (important when using LED lighting).
All the disadvantages of hidden wiring are the advantages of open wiring and vice versa. The advantages of open wiring include:
- ease of laying cable products;
- easy diagnosis and uncomplicated repair if necessary.
The disadvantages include:
- increased likelihood of mechanical damage;
- increased fire hazard (especially in wooden houses);
- problems with the subsequent wallpapering, painting the walls, etc.
And most importantly, the wires are in plain sight, which does not add to the aesthetics of the room.
The option is chosen after comparing all the advantages and disadvantages on the spot.
Preparatory work
Preparation for the arrangement of the lighting system begins with the identification of places to install a switch, switch box, fixtures. After that, the routes of laying cables are outlined. Further work depends on the type of wiring chosen.
Concealed laying is performed before finishing the walls. Along the planned lines, channels are made for laying cables - stroebs. It is most convenient to do them with a special tool - hole punching. Channels made with a bolt cutter or a hole punch are also not bad. As a last resort, you can use a hammer and chisel.
Important! It is forbidden to make horizontal entries in the load-bearing structures of the building! Other restrictions are contained in SNiP 3.05.08-85.
Then it is necessary to make notches under trunk plugs and boxes for soldering wires - this is done with a special drill (crown).
If plastic boxes are mounted in a plasterboard partition, it is necessary to use boxes of special design.
Open wiring is performed after the final finishing. Plastic troughs or racks are used for laying cables (if the wiring is done in the "Retro" style). To install switches and boxes must be fixed pads.
Video: Installing the socket block in the level.
Installing light fixtures
There are a great manyand fixing them to the ceiling and walls depends on their design and execution of the plane on which they are mounted. For proper mounting, you must study the instruction manual of the light fixture and follow it.
It is desirable to make the connection before installing the lamps (they will interfere and there is a risk of damaging them). If the luminaire is designed to use only incandescent lamps, phasing is not required. In other cases (LED-lights, energy-saving lamps), it is necessary to follow the order of connection:
- The phase wire must be connected to the L terminal;
- The neutral conductor should be connected to the N terminal;
- The protective conductor must be connected to the PE terminal (it is often marked with the ground symbol).
Failure to follow the phasing may result in malfunctioning of the light.
Installing a double
Before installing the two-button appliance, you must partially disassemble - Remove the keys and the decorative plastic frame. Then connect the wires according to the selected colors. It is desirable to connect the red wire (if it is in the cable) to the common terminal, which in the distribution box is connected to the phase wire of the incoming cable - so it is less likely to mix up the ends. You can connect any color wire to the outgoing terminals. If it turns out that it is more convenient to use a certain key to control a certain lamp, in the process of operation the wires can be switched.
After connecting the switch should be placed in the sub-socket, unclip the petals, fix the metal panel with self-tapping screws.
Making connections in the junction box
Cables inserted into the boxes for soldering must be cut:
- shorten to a reasonable length (so that the box can be closed after installation) - this is done with wire cutters;
- Remove the upper sheath - a utility knife will help;
- Strip the cores from the insulation by 1-1.5 cm - with a utility knife or a special puller.
Then the wires must be connected according to the diagram:
- The PE and N conductors through the box go in transit and are simply connected to each other in groups;
- The phase conductor from the fuse box connects to the phase conductor going to the common terminal of the switch;
- The conductors from the switchboard contacts are connected to the supply conductors of the outgoing cable to the consumers according to the circuit diagram.
It is convenient to make connections with the help of clamp terminals. But for reliability, it is better to use screw terminals, although wiring in this case is a little more complicated. You can simply twist and solder conductors, but after that they must be necessarily insulated.
Completing the installation work
To complete the installation work must be fully plastered strokes for open wiring, close the cable trays at the open. Close the solder boxes with the standard plastic covers for any type of installation. Then you can reinstall the plastic frames and movable keys that you removed before installing the switch and proceed to test the functionality of the lighting system.
Video unit: Wiring diagram for a two-way switch for two light bulbs.
Checking the lighting system
You can verify the proper assembly of the dual household switch wiring diagram by testing the wiring with a multimeter or by reconciling the wiring diagram with the colors of the wires. If the lighting system has not yet been connected to a circuit breaker, you can simulate the operation of the circuit using a battery.
To do this, connect a battery (preferably 9 volts) to the input of the circuit, and a multimeter in voltmeter mode to the terminals of the light (you can test lamp, which is guaranteed to light up at 9 volts). By turning on and off the corresponding button of the switchboard you can check if the voltage appears on the lighting fixture. By monitoring the polarity of the incoming DC voltage it is easy to determine the correct phasing. The advantage of this method is that if the battery is installed incorrectly, it will not deliver enough current to overheat or damage circuit components.
Health and Safety Regulations for Electrical Installation
To ensure safety when working in an electrical installation, the work must be done with the voltage off. To do this, connect the lighting system to the circuit breaker last.
The switchboard is considered a functioning electrical installation, so when you work in it must perform several technical measures:
- turn off the group (input) switch;
- to temporarily connect the power busbar of automatic circuit breakers to the PE conductor (if any);
- check the absence of voltage on the power bus.
All work must be performed with dielectric gloves and insulated hand tools. Safety regulations also require the use of dielectric mats.
Easy to understand step-by-step video: Wiring a switch during repair.
Breaking down common mistakes
When wires are connected carefully, especially those with color-coded strands, the likelihood of error is minimized. But if the conductors are not labeled or the installation was carried out in a hurry (when the deadline for delivery of the apartment is pressing), it is possible to connect the phase wire not to the common terminal of the double-switch, but to one of the outgoing terminals. This manifests itself externally as follows:
- when one key is manipulated, one light turns on and off normally;
- when the other key is manipulated, the second lamp does not turn on;
- both lamps light up when two buttons are on.
If this behavior of the lighting system is detected, it is necessary to find out the phasing with an indicator screwdriver and rewire.
And in general, the organization of the lighting system with the connection of household light switches with two keys, though responsible, but with a thoughtful approach and average skill master - quite realistic. It is possible to do everything yourself from scratch. The main thing - each action must be conscious.