Options for connecting two bulbs to one switch

There can be many situations when you need to connect two lamps to one power supply network using just one switch. Most often, single-key and two-key switches are used, less often, cross-switches. If, as a rule, there are no difficulties with connecting one light bulb, then the presence of 2 light sources makes home masters think about their proper connection to the network. However, I would like to list all of the possible ways, based not only on the type of switch, but also on the types of bulbs and how to connect them. Next, we will describe in detail how to connect two bulbs to one switch, providing all the necessary wiring diagrams.

Content:

Types of Lamps and Switches
The difference between parallel and series connection of lamps
Two light bulbs connection diagram
Single key switch
Two-gang switch
Feedthrough switches
Conclusion

Types of Lamps and Switches

Before you go directly to the installation, you need to clearly understand that there are several types of bulbs that connect to the network either directly or through ballasts or rectifier-lowering equipment. In any case, each of them has its own operating voltage and power, on which the current also depends.

Types of artificial light sources, often used in everyday life:

Incandescent and halogen, the principle of operation is the same only in some there is a vacuum, and in others there are special halogen vapors that increase the service life.
Luminescent, as well as their variety, the so-called housekeepers and sodium.
LED, operating on LED systems and on the features of a semiconductor diode, emit a luminous flux.

The main kinds of light switchesdesigned to control lighting can be divided into:

One-key, two-key, three-key, etc.
Pass and cross.

Each type of lamp has its own characteristics and connection schemes, even if they are connected to the same switch.

The difference between parallel and series connection of lamps

If any bulbs are connected in parallel to each other and, accordingly, in series with the switch, then the voltage on each of them will be equal and in this way it is possible to connect light sources of different power. The main condition is that the operating voltage at which they operate normally should be equal to the voltage of the power source. If in this case a step-down device with a rectification system is used, the opening contact must disconnect the circuit in front of the converter, as shown in the figure.

In this case, it is not significant that two or three light sources will be switched on. Most often these are halogen and LED lamps, designed for a reduced voltage of 12 or 24 Volts.

With a serial connection, the situation changes dramatically.The supply voltage will be divided by the number of bulbs, that is, if the network is 220 volts, then on two artificial light sources connected to the serial circuit, the voltage will be approximately 110 volts. This must be taken into account when choosing and buying. Another nuance with this connection is associated with the power of each of them. It should be the same or as close to each other as possible. with this connection, the current is the same in all parts of the circuit. If one lamp is rated at 500 watts and the other is 50 watts, then in a bulb with less power connected by one wire to each other, a higher current will still flow, corresponding to the most powerful load. A light bulb with less power will instantly burn out. This rule applies to all types of lamp sources, from incandescent to LED.

If you need to connect an LED light source from a network or from sockets, then often it consists of a so-called driver installed inside the lamp housing. It performs several functions at once: rectifying and lowering. For serial connection, these lighting devices are not intended, only for parallel.

For fluorescent daylight sources, both with an electronic starting device and with a starter, serial connection is most often found in raster lamps, as it allows using one throttle and two starters to ensure stable operation. In this case, the starter itself is selected at 127 V with the calculation of the operating voltage of a standard network 220 Volts. The switch in this circuit uses a conventional single-key switch and also breaks the phase wire with its contact.

As for the parallel connection of several fluorescent lamps or compact lamps, the operation of which is based on the glow of a phosphor deposited on a glass tube, in this situation, you can connect any quantity to one switch, both single-key and two-key. The main thing is to take into account the power of all light sources, on which the current in their circuit directly depends. For any circuit breaker, it is limited and is indicated in the technical passport, on the package or on the case. If, for example, a current of 5 A is indicated, then its value should not be exceeded, since this will very quickly render the disconnecting contact itself unusable.

To fully understand the serial and parallel connection of bulbs, we recommend watching the video:

Two light bulbs connection diagram

Single key switch

The connection of two incandescent bulbs to one switch is carried out according to the standard scheme, the only difference is how the light sources are connected. Using a switching device with one key, you can simultaneously control two lighting devices at once, no matter how they are connected to each other, in parallel or in series.

The main thing to remember is that it is recommended that the NC contact be put in phase, and the wire connected directly to the light bulb is zero. In the opposite case, of course, the circuit will also work, but then when replacing a burned-out light source, it becomes necessary to turn off the entire power supply of the room or area, since it is the potential that goes through the phase conductor that affects the human body. Determine phase easily using a conventional indicator screwdriver or tester.

Two-gang switch

If everything is clear with the connection of two bulbs to a single-key switch, consider a switch with two keys and its features of operation and connection. It has one common contact and two outgoing, going to a separate load. In this case, the entire installation must be carried out through the junction box, this will further simplify the connection of new lighting devices or troubleshooting. The wiring to the switch is carried out by a three-wire wire, and the wiring through the lamps and the input of the supply voltage are two-wire.

A double switching device can be used for separate control of two light sources of any type, most importantly, again, do not forget about limiting the current in the circuit. It is precisely by the strength of the current flowing in the circuit of lighting devices that you need to choose the switch itself and the wire section.

The video below clearly shows how to connect two lamps to a double switch:

Feedthrough switches

The connection of two bulbs to the passage switch is used when lighting long corridors and tunnels and for this they are necessarily used in pairs, otherwise the meaning of their use is lost. Here is a schematic diagram for such a connection. All installation also needs to be done through the junction box:

The whole essence of connecting two or more lamps to the passage switch is provided in the video:

Conclusion

The series connection of two lamps to the network through the switch has one negative side and therefore is rarely used. It lies in the fact that when a single light source fails, the whole chain ceases to work, and this is very inconvenient. With a parallel connection, there is no such effect, therefore, it is the most common and demanded both in domestic conditions and in production. As for the switch itself, its main working element is the contact part, which is designed for a certain current, and exceeding this rating will lead to its overheating, burning and, as a result, to failure. We hope you now understand how to connect two bulbs to one light switch and which circuit is the most suitable!

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