How to connect a light bulb to two switches
In some cases, there is a need to fully control the lighting from two points. This may be needed in production with long aisles or warehouses with multiple exits. A person entering through one entrance can exit through another and turn off the light behind him. In everyday life, such a need may arise in the bedroom - it is convenient to turn on the lighting at the entrance, and turn it off next to the bed. The creation of such schemes is possible, but there are some features that are offered for review.
Pros and cons of multi-point control
The main advantage of the solution to connect 2 switches to 1 light bulb is an increase in the level of comfort. Such a scheme allows you not to waste time returning to the installation site of the switching device in order to deactivate the lighting. Also, the use of such a control principle allows you to save energy by reducing the operating time of lighting elements.
There are few disadvantages of such a system, but the main one is by the position of one switch it is impossible to determine whether the voltage is applied to the lamps. Also, the disadvantages include the need to make additional technical solutions, if necessary, priority control of light from the central console.
Which switches to use
On conventional (key) switching elements, working for closing-opening, it is possible to implement various schemes for connecting two switches to one lighting lamp.
The conclusion is unambiguous - with the help of simple switches it is impossible to organize a full-fledged scheme of independent control from two places.
Through switch
In this case, you need to apply walk-through (marching) lighting switches. Outwardly, in most cases they do not differ from standard ones, but they have a specific contact group.
If the key apparatus opens the electrical circuit in one position and closes it in the other, then the marching device works differently. In one position, it closes one circuit (the other is open), in the second position it is closed, on the contrary, the second circuit (the first is broken). Therefore, such devices are often called switches.
Marching devices are available in single-key and two-key versions. The latter are distinguished by the presence of two contact groups, which are independently controlled by two keys.
Sometimes a marking in the form of a flight of stairs or two arrows is applied to the front side of the pass-through device.
But there are no uniform requirements for marking on the front panel of switching devices. Many manufacturers, both global giants of the electrical industry and little-known firms, often neglect such marking. Therefore, you can determine the purpose of the device in other ways:
- asking the seller
- having studied the passport for the switch;
- according to the markings on the back.
On the back, a contact group diagram and the connection of each element to the terminals are usually applied.
Some manufacturers mark the terminals with alphabetic characters instead of a diagram. For example, a changeover contact with a letter L, and the fixed elements N1 and N2. There is also no common standard here, so the letters may vary.
Connection diagram for two devices
A marching switch can be used as a conventional switching device, but this is irrational - it costs more than a standard key. Devices with a changeover group are specially produced for the organization lighting schemesindependently controlled from two or more points.
This scheme is made up of two successively connected marching instruments. Obviously, no matter what position one of the switches is in, the second one can always close or open the power supply circuit of the lamp.
If you need a control scheme from three or more places, then together with marching switches it is necessary to use cross devices. It is not possible to build such a system on one checkpoint. On the other hand, if there are two pass-through two-key devices, it is possible to organize independent switching on of two light sources from two different places.
Such a scheme is useful, for example, where there are two lighting systems in the same room - general and local. In this way, you can set two levels of brightness in steps.
Security conditions
The main condition for the safe operation of the lighting system is that all its elements must be in good working order. In the process of work, it is necessary to monitor this and replace the failed elements in time (also observing the rules of labor protection).
The installation of the elements of the lighting circuit must be carried out in such a way that the current-carrying parts are inaccessible to intentional or accidental contact. All connections in junction boxes must be insulated after completion of work and before the first supply of voltage. The applied switching elements must be rated with a margin (at least 20%) for the full load current.
| Through switch | Number of contact groups | Maximum load current, A |
|---|---|---|
| UNIVersal Allegro IP-54, ser. 1276 | 1 | 10 |
| Jilion 9533456 | 1 | 10 |
| Lezard DEMET backlit cream 711-0300-114 | 1 | 10 |
| Panasonic Arkedia white 54777 WMTC0011-2WH-RES | 1 | 10 |
| Livolo VL-C701SR-14 Touch | 1 | 5 |
Obviously, it makes no sense to look for a device designed for a current of more than 10 amperes - such a load will be turned off by a line protection circuit breaker.
If the circuit will be operated on a TN-S or TN-C-S network (with a PE conductor), then this conductor must must be laid to each lamp. If at the time of installation there is nowhere to connect it (for example, if incandescent lamps are used), then in the future it will still come in handy when replacing lighting elements with more modern ones. If luminaires with protection class 1 are used, grounding is the only way to ensure safety during operation. For such devices, the PE conductor must be connected to the terminal marked with the earth symbol (or the letters PE). Without grounding, such chandeliers cannot be operated.
Video: A simple way to connect 2 switches into one lamp.
The circuit must be connected to a separate circuit breaker in the switchboard. Many years of experience have established that lighting networks are made with copper wire with a cross section of 1.5 sq. mm. A larger cross section is unjustified economically, a smaller one may not pass through the load current and mechanical strength. To protect such a line, it is necessary to install automatic machine for current 10 A. If you use a protective device with a high current, then its sensitivity may not be enough, which will lead to overheating of the wires and melting of the insulation. The use of automata with a lower current must be confirmed by calculation - it should not falsely operate at rated load with a margin of 20-30%. In many cases, 6 amp circuit breakers can be used, especially when building a lighting network on LED lamps.
It will also be useful: 4 steps to install the switch on the wall
Connecting two switches to one light bulb should not cause insurmountable difficulties for a master who has at least basic knowledge of electrical engineering. The materials of this review will help in case of doubt.