A three-key pass-through switch is an electrical device designed to control one light source from different places. Visually, it has many similarities with the usual switches, the principle of operation is the same - closing and opening the lighting circuit.
Why do I need a three-key crossover switch
The triple pass-through switch allows the consumer to control one or more light sources from different locations. Installation of the device is advisable in rooms with a large area, for example, in country houses and long corridors, in stadiums and concert venues and basements.
A country house with several floors is convenient to equip with such devices. For example, going up to the second floor, you can turn off the lighting devices on the first. Also, a triple switch is often installed to control street lighting.
Design and principle of operation
The triple pass-through switch circuit does not differ from traditional devices externally. The only significant difference is that the first one is equipped with a working unit of the contact group, placed inside the case. In a pass-through switch, when the position of the key is changed, one circuit opens, and the other immediately closes. This principle of flipping contacts allows several switches to work in pairs, controlling one light bulb.
The principle of operation of the switch is based on the presence of reverse electrical conductors in the switching device. The work is carried out as follows: when the position of the keys is changed, one circuit is simultaneously closed and the other open. Due to such features of the device, it would be more correct to call the device not a switch, but a switch. Also, experts refer to it as a redundant, cross and rocker switch.
Lighting control from two places
Three sections of the chain are involved in lighting control from two locations:
- The cable from the mains (220 V) is led from the circuit breaker located in the switchboard to the box.
- Wire from one crossover device to a junction box.
- Wire from the second crossover to the breakout box.
Three electrical wires are inserted into the control box. To control the lighting from two places, a two-key pass-through switches connection scheme is used.
Lighting control from three locations
You can also install this type of design in any convenient place. In the circuit, a redundant device is connected between ordinary pass-through switches. They can be used at any request of the customer, for example, on a personal plot, in staircases, long corridors.
You can build such a device with your own hands, without having specific knowledge and skills. This requires minor design changes to the two-key crossover device.The output contacts are equipped with two jumpers, and the keys are combined into one, just glue them together. It is important that when connecting, the mounting connectors on the keys match the pins located on the switch. It is not at all necessary to make it yourself at home; in hardware stores, the seller will offer a large assortment of switches.
Usage example
For example, returning in the evening to a private house, you need to reach the front door through a dark courtyard. In this case, it is appropriate to mount the cross switch in multiple locations. Not far from the switchboard located in the corridor, a junction box and one cross switch are mounted. For the second, the most suitable place is on the fence near the gate.
Lighting devices on the street can be small lampposts installed along the infield. There is a large assortment of street "chandeliers" with different designs in hardware stores in the electrical department.
It is preferable to lay electric cables from street lighting in trenches underground in special plastic pipes. The optimum burial depth is no more than half a meter. It makes no sense to take into account the depth of soil freezing, since copper electric cables are not afraid of low temperatures.
If there is one large chandelier in the room, equipped with two groups of lamps, or there are several sconces along the corridor, it is better to use not three-key devices, but two-key cross switches in combination with redundant ones. The connection diagram is a little more complicated, but experts note the advantages of this particular connection method.
Of the disadvantages of an electrical device, only the high cost can be noted. High-quality switches have an attractive appearance and long service life, do not cause difficulties in installation.
You can buy electrical devices in any hardware or household store, it is better to give preference to more expensive models, since they are made of high-quality materials in comparison with budget counterparts.
