One of the most frequent questions we receive at Tegui-Distel is: "I have 6 wires in the wall, what system do I have?" or "I don’t know if my intercom is 2 wires or 4+N". This is completely normal: video intercom systems have evolved a lot and are not always obvious to identify at first glance.
In this guide, we explain how to identify your installation easily, without needing to be an expert.
How to count wires: the first step
The first thing you should do is open the box of the phone or indoor monitor and count the wires connected to the device. This count will give you a crucial clue:
- 2 wires: you almost certainly have a 2 wires (digital BUS) system. It is the most modern system and the most widespread in new installations since the 2000s.
- 4 or 5 wires: you probably have a 4+N system (also called 4 wires + neutral). It is the most common traditional system in Spain until the mid-2000s.
- 6 or more wires: it may be an old analog system or a 4+N installation with separate power. In this case, it is advisable to consult an installer.
Important: count only the wires connected to the device terminals, not those loose or disconnected.
Difference between BUS (2 wires) and 4+N
Although both systems serve the same function —allowing you to see and talk to whoever is at your door— they work very differently:
2 wires system (digital BUS)
The 2 wires system from Tegui/BTicino uses only two wires to transmit everything: video, audio, power, and control signals. This is possible thanks to digital BUS technology, which multiplexes all signals over a single pair of wires.
- ✅ Only 2 wires between panel and monitor
- ✅ Easier and more economical installation
- ✅ Compatible with modern monitors like the Kit A1 Linea 3000 Classe 100A16E (€249.99) or the Kit V1 2 Wires Classe 100V16E (€517.59)
- ✅ Allows adding WiFi and mobile app on many models
- ✅ Scalable: you can add more monitors without new wiring
The Audio/Video RFID Panel Linea 3000 Black 2-wire (€316.85) is an example of an outdoor panel compatible with this system.
4+N System
The 4+N system uses separate cables for each function: one for video, one for audio, one for door opening, one for call, and the power neutral. It is an older analog system but very reliable and still very common in buildings built before 2005.
- ⚠️ Requires 4 or 5 cables between panel and phone
- ⚠️ More complex installation with more wiring
- ✅ Very robust and tested for decades
- ✅ Compatible with phones like the Kit A1 Tegui Series 7 (€65.99) or the Kit A2 with 2 S7 Phones (€116.08)
How to distinguish them visually? In the 4+N system, the cables usually have different colors (red, black, yellow, green, white). In the 2-wire system, the two cables are generally the same thickness and may be the same color or simple colors.
How to know if your installation supports WiFi
This is another very common question: "Can I add WiFi to my video door phone without changing the whole system?"
The answer depends on the system you have:
If you have a 2-wire system (digital BUS)
Good news! Most Tegui/BTicino 2-wire installations are compatible with modern WiFi monitors. Models like the Classe 100 WiFi or the Classe 300EOS connect directly to the existing wiring and allow you to receive calls on your smartphone through the Door Entry app.
You only need to replace the indoor monitor: the wiring and outdoor panel do not change.
If you have a 4+N system
In this case, adding WiFi is more complex. The options are:
- Conversion adapters: there are modules that convert the 4+N signal to 2-wire BUS, allowing you to install a modern monitor with WiFi. However, they are not always compatible with all panels.
- Complete replacement: if the installation is old or you want all the modern features, the best option is to renew the entire system to 2-wire.
Tip: before buying any component, check the exact reference of your outdoor panel. This will allow us to confirm compatibility without any margin of error.
Common mistakes when identifying the system
These are the most common mistakes we see when customers try to identify their installation:
❌ Error 1: Counting all the cables in the conduit, not the connected ones
In many installations, the conduit has more cables than are actually used. Count only those connected to the terminals of the phone or monitor. Loose cables don’t count.
❌ Error 2: Confusing the system by the number of floors
Some believe that large buildings always have 4+N and single-family homes always have 2 wires. This is not true: the system depends on the installation year and manufacturer, not the building size.
❌ Error 3: Assuming all 2-wire systems are the same
There are different versions of the 2-wire system on the market. The Tegui/BTicino BUS system is not compatible with the 2-wire system from other brands (Fermax, Comelit, etc.). Make sure the components are from the same family.
❌ Error 4: Buying a monitor without checking panel compatibility
The monitor and the outdoor panel must be compatible with each other. Before buying, note the reference of your current panel (usually on a label on the back or bottom) and consult us.
❌ Error 5: Ignoring the power supply
In 2-wire systems, the power supply is a critical component. If you have more than one monitor or a large installation, you may need an additional power supply. An installation without the proper power supply can cause image or door opening problems.
Still not sure? Ask us
If after reading this guide you still have doubts about which system you have, don’t worry. At Tegui-Distel we have years of experience helping installers and individuals identify their systems and find the right components.
You can contact us with the reference of your outdoor panel or with a photo of the cables of your indoor monitor, and we will guide you without obligation.
And if you already know what you need, explore our complete kits to easily upgrade your installation:
- Kit A1 Line 3000 Classe 100A16E — 2-Wire System — €249,99
- Kit V1 2-Wire Classe 100V16E-Line 3000 — €517,59
- Kit A1 Tegui Series 7 — 4+N System — €65,99
- Kit A2 with 2 S7 Phones — 4+N System — €116,08