How to choose a pass-through switch: device and purpose of various types + markings

To control lighting devices on a staircase or in a long corridor, the usual circuit with one “on/off” device is not suitable. To turn off the light in such a situation, you will have to go back to the only switch in the room. Not too convenient, don't you agree?

By installing a pass-through switch that allows you to control light bulbs from two places, you will significantly increase the level of comfort in your home or office. We will tell you how to choose the right device and how to install it correctly. Our article discusses popular connection options.

Selecting devices: switches vs switches

Before you go to a lighting store to buy the necessary materials, you first need to understand the terminology and various electrical switching devices.

For most novice electricians, a switch and a switch are the same thing. However, they are only superficially similar to each other. According to the principle of operation, these devices differ radically.

Both household switches and light switches look the same and have uniform housings, but are designed for fundamentally different connection schemes

A regular “SWITCH” is the simplest key that opens/closes an electrical circuit. It has one incoming and one outgoing wire. Plus, there are two- and three-key devices with a large number of contacts.However, these are simply two or three switches assembled together in a single housing.

A “SWITCH” is a switching device in which one incoming electrical circuit is switched to one of several output circuits. Often, such a device is also called a “changeover switch”, since it has a key for switching contacts from one position to another.

At a minimum, such a single-key device has three contacts (one incoming and a pair of outgoing). If there are two keys, then there are already six terminals (a pair at the input and four at the output).

The term “PASS-THROUGH SWITCH” refers to several switches connected to each other according to a specific circuit. Such a switch is designed to turn on/off a single light source from several points in a room or fenced area with lighting at once.

It is impossible to make a “pass-through” device from classic switches in order to save on purchases; for this it is necessary to use only switches

As a result, a two-pin switch is designed to break one electrical circuit with the phase through which the light bulb is powered. And a three-pin switch is used to create new separate power circuits.

The first option is needed to stop the flow of current through any circuit, and the second option is needed to switch between circuits. Externally, both devices look exactly the same. This is a housing with one or more keys. In this case, the switch can be used in switch mode, but vice versa cannot.

It is impossible to turn a two-pin device into a three-pin one. But eliminating the use of one of the circuits is quite acceptable.But to organize light control from several points, you need to buy only switching devices with three or more contacts.

Types of household switching devices

Switches come in push-button, key and rotary types. The first option is usually used only as a bell at the front door. It is not suitable for lighting control.

But the second type for turning on/off lights in a residential building is just what you need. The rotating version is more intended for production and utility rooms. Such products do not have a very presentable appearance.

Depending on the number of keys, switches are:

• single-key;
• two-key;
• three-key.

They are divided into ordinary (pass-through), combined and cross (intermediate). The first ones have three contacts. For the latter, this three terminals is increased by multiplying by the number of keys. And the third has two entrances and exits. The latter are intended for circuits with not two, but several light switching points.

By type of control in private homes, light switches are usually standard keypads, but there are also models with sensors and remote control

According to the wiring diagram, switches are for open (overhead products) and hidden (built-in analogs) wiring. The first ones are fastened to the wall with self-tapping dowels, and the second ones are fixed in the socket boxes with the help of expanding legs.

When choosing switches for connection according to the pass-through switch circuit, it is necessary to correctly select the number of keys (one for each connected group). If you plan to make two control points, then you will only need a pair of ordinary three-pin devices.

If more of these points are needed, then for each such place you will have to additionally take an intermediate crossover device to be included in a single system.

In the vast majority of cases, the key of a household switch has two positions for closing one of the circuits. But there are also modifications with a zero middle state. In this situation, both circuits are broken.

Marking on the switch body

The part of the switch where the contacts are located usually has special markings indicating the characteristics of the switching product. At a minimum, these are the rated voltage and current, as well as degree of IP protection and designations of wire terminals.

If the switch is selected for circuits with fluorescent lamps, then its marking must contain the letters “X” or “AX” (on ordinary ones there is only “A”)

When the light in fluorescent lamps is turned on, a sharp surge of inrush current occurs in the circuit. If LED or incandescent light bulbs are used, then this jump is not so large.

Otherwise, the switch must be designed for such high loads, otherwise there is a risk of burning the contacts in its terminals. This is why it is so important to choose special switches for fluorescent electric lamps.

For installation in a bedroom or hallway, a switch with IP03 is quite suitable. For bathrooms, it is better to raise the second digit to 4 or 5. And if the switching product is installed outdoors, then the degree of protection should be at least IP55.

Contact clamps for electrical wires on the switch can be:

• screw with and without a pressure plate;
• screwless spring.

The former are more reliable, while the latter greatly simplify electrical installations. Moreover, the best option is screw clamps with an addition in the form of a pressure plate. When tightened, they do not destroy the wire core with the tip of the screw.

According to GOST requirements, if the conductor has a cross-section of up to 1.5 mm, then it is unacceptable to use a screw clamp in which the end of the screw is rotated along the core to connect it to the switch

Also in the switch markings there are terminal designations:

1. “N” – for the neutral working conductor.
2. “L” – for a conductor with a phase.
3. “EARTH” – for the neutral protective conductor to be grounded.

Plus, usually using “I” and “O” the position of the key in the “ON” and “OFF” modes is indicated. Manufacturer logos and product names may also be present on the case.

Lighting control from several places

There are several schemes for installing switches to turn on light from different ends of the corridor. The simplest of them involves the presence of switch keys in two places in the room remote from each other and one power line for the lamps.

If it is necessary to make more than two lighting switching points, then wiring the electrical wires will be somewhat more complicated. But there is nothing particularly wise here either.

If you follow the presented diagrams for connecting switches, then there will be no special problems with organizing control of the lamp from several points - you just need to avoid mixing up the wires

If, using a pass-through switch, you plan to supply voltage to a chandelier with two or three separate sets of light bulbs, then the circuit will become somewhat more complicated.Here you will have to mount switches with several keys, and there are much more terminals for wires.

Scheme #1: to turn on the light from two points

The easiest way is to organize control of the lighting fixture from two different places in the room. To do this, you only need a couple of standard switches and a few meters of electrical wiring.

Plus, you will need to follow the simplest rules of electrical installation to prevent electric shock and ensure the safe operation of the entire system in the future.

The “pass-through corridor switch” circuit with two switches is the most popular, it is widely used in corridors and bedrooms, as well as on stairs and verandas

When implementing connection diagrams from several places the outputs of both switches are connected by a pair of wires to produce two separate supply circuits. Then a wire with a phase is connected to the input of one switching product, and a lead to the light bulb is connected to the input of the second.

As a result, in any position of both keys, the common power circuit of the “pass-through switch” will be either broken or connected. The light can be turned on and off from two different points.

This solution allows you to supply voltage to the lighting device when only one key is turned on. The second, on the other side of the room, always commutes one of the existing lines.

Scheme #2: for two lamps

The first scheme is the simplest and cheapest to implement. It is used most often. However, if there are several lamps in the room or the light bulbs in the chandelier are divided into two groups, then a similar version of a pass-through switch will not work.

If you need to supply power to two separate lines of lighting lamps, you will have to resort to installing two-key switches with six contacts each

In terms of installation technology and the devices used, this scheme practically repeats the first basic option. Only in this case you will have to lay more wires.

And in order to save at least a little on them, it is recommended to make the supply wire to the first switch in the circuit with a jumper. Pulling a couple of separate wires from the distribution box will be too expensive.

If there are three lines with lamps, then two-key switches change to three-key analogues. In all other respects, the wiring diagram remains the same, only their number increases.

Scheme #3: for several switches

With two light switching points and one or more lighting groups, everything is quite simple. It needs some wiring and a couple of switches. But if you need to organize control from several places, you will have to purchase another type of switching device.

If you need to install several switches for one lamp, then you cannot do without a cross switch. In this device one of the circuits is transit

In such connection diagram extreme switches are installed as usual pass-through ones, as in the first case. And between them a crossover analogue with four terminals for connecting the electrical wiring is then mounted.

When you press a key in such a switching device, the connected contacts are opened and immediately cross-connected into a new supply circuit. In addition to single-key cross switches, there are devices with a large number of keys.They are designed for circuits with several groups of light bulbs.

However, in this case, much more cores will have to be connected to the terminals. And here it is extremely important not to confuse anything. It is necessary to pay special attention to the correct electrical installation during such wiring.

If another “on/off” point is needed, then another crossbar is installed with serial connection of wires to the existing ones

Electricians recommend connecting switches to each other through a junction box. However, it is much easier to do this directly using a two-wire wire. Practice shows that such a connection is more expedient and does not violate electrical engineering standards. And the consumption of electrical wires is seriously reduced.

Field-tested cross-switch connection diagrams are given in next article, the contents of which we advise you to familiarize yourself with.

Conclusions and useful video on the topic

There are few nuances of connecting switches so that lighting can be controlled from several points. But they exist. And you cannot miss them out of ignorance of their type when performing installation. To make it easier for you to understand all the intricacies of the schemes described above, we recommend that you watch the video materials below.

All about walk-through switches - principles of operation and installation:

How to connect a two key switch:

Connection diagram for pass-through (changeover) switches through a distribution box:

The use of pass-through switches greatly simplifies lighting control in a large room, making this process more convenient. It is not difficult to independently install such a system from several switches and wires.You just need to choose the right set of necessary switching devices.

How did you choose a pass-through switch for installation in a country house, office or apartment? What was the decisive argument for you in choosing a device? Please write comments in the block below, post photographs related to the topic of the article, share useful information and ask questions.