Are you going to change your video intercom and don’t know if you have a 2-wire system or a 4+N wire system? This is the most common question we get asked. In this guide, we explain it clearly so you don’t make mistakes when buying.
What is a 2-wire (BUS SCS) system?
The 2-wire BUS SCS system is the most modern technology from Tegui/BTicino. As its name indicates, it uses only 2 cables to transmit audio, video, and power. It is the system installed in most homes built or renovated from the 2000s onward.
Advantages of the 2-wire system
- Simpler and more economical installation
- Only 2 cables between the panel and monitor
- No polarity: connection order does not matter
- Compatible with modern monitors with WiFi and app
- Easy expansion to multiple monitors
What is a 4+N wire system?
The 4+N wire system is the conventional or analog technology, older. It uses 4 or more cables each with specific functions (audio, video, power, door release...). It is the typical system in homes built before the year 2000.
Characteristics of the 4+N system
- More cables and specific connections
- Each cable has a specific function
- Compatible with universal intercoms like the Tegui T-71U (ref. 374240)
- Fewer modernization options without changing wiring
How to know which one I have?
It’s very simple: remove the monitor or intercom from the wall and count the cables connected to the terminal:
- ✅ 2 cables → you have a 2-wire BUS SCS system (modern Tegui/BTicino)
- ❌ 4 or more cables → you have a 4+N wire system (conventional analog)
Another clue: if your outdoor panel has a sticker or engraving with "BUS" or "SCS", it is a 2-wire system.
Are they compatible with each other?
No. The 2-wire and 4+N systems are not compatible. A monitor designed for 2 wires will not work in a 4+N installation and vice versa. That’s why it’s essential to identify your system before buying any component.
Quick summary
- 2 cables at the terminal → 2-wire BUS SCS system → Tegui Serie 8, Swing, Classe 100X16E WiFi monitors
- 4+ cables at the terminal → 4+N system → universal intercoms like Tegui T-71U
⚠️ Still have doubts? Send us a photo of your installation and we’ll tell you exactly which system you have and what product you need.