Video intercom - a system that allows you to talk with visitors, open the door or prohibit entry from a distance. It consists of devices that provide image and sound transmission and linking these wire elements. The cable for the video intercom must be selected carefully, since it determines the quality of the device.
Cable features
Any wire consists of 2 elements:
- The conductive core is made of copper or aluminum wire, it transfers electric current.
- Insulation is a sheath. It does not allow mechanical damage to the core, protects against moisture and sunlight, prevents the influence of external noise, and shields the conductive core.
Insulation is determined by the type of intercom and installation method. If the wires are laid inside the building, especially in a private house, they have only one requirement: to reliably protect the consumer from electric shock. But if the cable is installed on the street, choose the option with a sheath of polyethylene.
Noise immunity, provides a metal sheath of a vein - the screen.
Basic cable requirements for video intercom
Laying a wire for a VCR is one of the construction works, so the requirements are strictly regulated:
- since the electromagnetic field created by the wire affects the operation of the devices, only shielded cables are taken for the system;
- the greater the distance between the common calling panel and the subscriber, the greater the cross-section should be;
- isolation must be intact. Areas with damaged shells must be replaced immediately;
- the worse the weather in the area, the higher the level of protection should be.
You need to use wires that exactly match the type of intercom and installation conditions.
Cable for video intercom with electromechanical lock
An electromechanical or electromagnetic lock can be connected to the video intercom. The first is more reliable: in the absence of electricity, the door remains closed. The electromagnetic lock requires constant power and when the current is turned off, it stops working.
If the electronic lock is connected to the intercom, it is necessary to provide it with current, since a regular battery from the subscriber unit will not be enough. As a cable for a household video intercom with an electromechanical lock, the same wire is used - such as UTP. It is better to choose the option in which the wires through which the current is supplied were from two twisted cores.
To power the electric lock, you need a voltage of no more than 24 V.
Cable for video intercom 4-core
Such a device requires only a 4-wire version: 2 conductors provide sound transmission, 2 - images. If the wire is laid in the house, you can use a cable with a foil screen. If the line is laid on the street, you need a coaxial.
The cable includes 4 conductors and a shielding. It is located coaxially with the conductor and is separated by an insulating polymer - polyethylene or polypropylene. The structure is complex: a copper or steel core is insulated with a layer of polyethylene, covered with foil and braid of copper or aluminum. The last layer is rubber or plastic insulation.
It is recommended to take coaxial wires for the intercom in a private house or in an apartment if the distance between the elements of the system is small.
Cable for connecting video intercom and door station
Which cable to connect the panel and video intercom, depends on the distance.The greater the distance, the higher the conductivity should be. General recommendations:
- For small distances - up to 20 m, take a twisted pair cable. It consists of 2 conductors twisted together and insulated with a polyethylene sheath.
- For distances up to 40 m, it is convenient to use a combined conductor.
- At a distance of up to 50 m, coaxial ones are suitable.
- If the distance is greater, the coaxial is combined with a separate supply wire.
Cables from reputable manufacturers are preferred.
Materials for the manufacture
On the market there are designs with copper and steel copper-plated veins. The former reliably and better transmit a signal. Steel conductors are poorly fixed by terminals, corrode and become unusable faster.
For external insulation, foamed / light-resistant polyethylene, propylene, polyvinyl chloride are used.
Types of cables
For a conventional video intercom, you need a cable that transmits a video signal to a subscriber device, as well as a power supply. They are selected according to technical requirements.
Coaxial cable RK-75
This is the main option for transmitting analog images. The impedance is 75 ohms. It is durable, inexpensive, but tough. For connecting to the devices you need a connector for crimping. It costs more.
The wire for the video intercom is better to take in a shell of foamed polyethylene. It can be bent.
Combined cables KVK
Ideal for a system with an electronic lock, as it simultaneously acts as a supply wire and a conductive one. Includes a standard coaxial cable with a wave impedance of 75 Ohms and a two-wire cable for supplying electric current.
Inside the building, a structure with a polyvinyl chloride shell is laid. For outdoor installation, models with foam polyethylene insulation are taken. They can be laid in the ground, but inside a metal or plastic pipeline. Installation of an overhead line is allowed - on a steel cable for support.
For installation in different conditions, choose the appropriate brand of KVK.
Twisted pair
It is used when servicing digital devices. Consists of 1, 2, 4 and more lines. Each represents 2 single-core conductors twisted with a certain step. There are many modifications of the "twisted pair":
- UTP - wire without a screen;
- FTP - there is a common foil screen;
- STP - each pair of cores is protected by its own screen;
- SFTP - each pair is protected by a screen, and the entire bundle is isolated by a common shell;
- U / FTP - general shielded protection.
ShVEP cable
The wire is designed specifically for intercom. It can transmit video signal, supply power and provide electronic lock control. Designed for outdoor installation and has reliable protection. Includes several stranded wires, of which one is protected by its own shield.
ШВЭП will be used when laying communications at a distance of up to 60 m.
Cable selection
What cable is needed for the video intercom, is determined after evaluating the following parameters:
- distance between the monitor and the call panel;
- installation conditions - inside the house, on the street, underground, by air;
- the number of electrical noise - if the wire passes in a room with a large amount of equipment, a shielded version is needed;
- temperature - with a large temperature difference, a model with polyethylene insulation is needed.
The most famous of domestic products are KVK cables. The design is designed specifically for doorphone service and is suitable for any installation method. The option is universal and reliable.
Coaxial cables from Cavel, Belden, CommScope differ in quality. Models marked RG-6 or RG-59 are chosen. The number indicates the thickness of the insulating layer - 6 and 5.9 mm. The wire provides image transmission in the temperature range from -60 to +120 C.
Connection Features
There are several features of connecting a conductor for a video intercom:
- Connect wires through screw terminals.
- Through the foundation, walls or column of the fence, the wire is passed through a protective sleeve.
- Do not lay the conductor for the intercom next to the 220 V power cable in one plastic cup.
- When installing several lines in parallel, the distance between them should be at least 10 cm.
- Immediately before connecting, remove the shell from the end. For reliability, they are crimped with tips.
- On the reverse side of the casing of the call panel, wires with different colors and corresponding markings emerge. The cores are connected to each other according to a certain pattern by crimping. The joints are insulated with thermotubes.
It is recommended that devices be connected in solid pieces of cable. The smaller the twists, the higher the signal quality.
