When you manage a small apartment building with three units, you need an intercom system that is simple, reliable, and easy to install. The FARHD 3-button outdoor station paired with three indoor monitors delivers exactly that—using a 2-wire connection through a 2-wire switch. No complex cabling, no network configuration, no Wi-Fi dropouts. Just clear video, two-way audio, and secure door release for each apartment.

In this blog, we explain how the system works, how to wire it, how to configure room numbers and button mapping, and why it is the ideal solution for small multi-unit residential buildings.

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Why 2-Wire for a 3-Unit Building?

The 2-wire system transmits power, audio, video, and control signals over a single pair of standard two-core wires. The connection is non-polarity, meaning you can connect the wires either way without risk of damage.

Key advantages:

• Reuses existing cabling – often works with old doorbell or telephone wires.
• Fast installation – any electrician can complete the wiring.
• Up to 100 metres transmission – enough for most small buildings.
• Economicamente vantaggioso – lower material and labour costs.
• Reliable – no network dependency, no Wi-Fi interference.

For a three-unit building, the 2-wire system is the most practical choice.

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System Components

A typical 3-button 2-wire kit includes:

Componente	Role
3-Button Outdoor Station	Three call buttons, one for each apartment. Includes camera, microphone, speaker, and optional card reader.
3 Indoor Monitors	One per apartment. Answer calls, view video, unlock door.
2-Wire Switch	Distributes signals to the three indoor monitors and outdoor station.
Alimentazione	15V DC adapter or central power supply.
2-Core Cable	Non-polarity, ≥0.5mm², up to 100m per run.
Electric Lock	Controlled by relay output. Requires separate 12V DC power supply.

The 2-wire switch is the heart of the system. It provides stable power distribution and isolates each indoor monitor, so a fault in one apartment does not affect the others.

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Wiring Topology: Star Wiring with 2-Wire Switch

For a 3-button system, the recommended wiring is star topology using a 2-wire switch.

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[Outdoor Station] ── 2-wire ── [2-Wire Switch] ── 2-wire ── [Indoor Monitor 1]
                                                   ├── 2-wire ── [Indoor Monitor 2]
                                                   └── 2-wire ── [Indoor Monitor 3]

Vantaggi:

• Fault isolation – one unit’s issue does not affect the others.
• Easier room number configuration.
• Scalable for future expansion (additional monitors or outdoor stations).

Alternative: Direct Bus Wiring (Not Recommended for 3 Units)

• Connect all monitors in series along a shared 2-wire bus.
• Simpler cabling, but a fault on the bus can affect multiple apartments.
• Room number configuration must be done carefully.

Raccomandazione: Use a 2-wire switch for star wiring. It provides stable power distribution and simplifies troubleshooting.

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Step-by-Step Wiring Guide

Step 1: Mount the Outdoor Station

• Mount at 1.5–1.8 metres above ground, protected from direct rain and sunlight.
• Use the included rain cover and mounting bracket.

Step 2: Mount the Indoor Monitors

• Mount each monitor in a convenient indoor location (hallway, living room, or bedroom).
• Recommended height: 1.2–1.4 metres.

Step 3: Run the 2-Wire Cables

• Use 2-core cable (≥0.5mm²).
• Keep cable runs under 100 metres. For longer distances, use thicker gauge (0.75mm² or 1.0mm²).
• Avoid running cables parallel to AC power lines to prevent interference.

Step 4: Connect the Outdoor Station

• Connect the 2-wire cable to the outdoor station’s terminals. Polarity does not matter.
• If an electric lock is used, connect the lock wires to the relay output (NO and COM).
• A separate 12V DC power supply is required for the lock.

Step 5: Connect the 2-Wire Switch

• Connect the cable from the outdoor station to the switch’s input.
• Connect each indoor monitor’s cable to the switch’s output ports.
• Power the switch with the supplied adapter.

Step 6: Connect the Indoor Monitors

• Connect each monitor’s 2-wire cable to the switch output.
• Ensure each monitor receives power via the 2-wire connection.

Step 7: Power On and Test

• Power on the system.
• Press button 1. Indoor Monitor 1 should ring.
• Press button 2. Indoor Monitor 2 should ring.
• Press button 3. Indoor Monitor 3 should ring.
• Test two-way audio, video, and unlock function.

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Configuration: Room Numbers and Button Mapping

After wiring, each indoor monitor must be assigned a unique room number, and each button on the outdoor station must be mapped to the correct apartment.

Step 1: Assign Room Numbers to Indoor Monitors

Via Indoor Monitor Menu:

1. Enter the Settings menu.
2. Seleziona Room Number o Address Setting.
3. Enter the apartment number (e.g., 101, 102, 103).
4. Save and exit.
5. Repeat for each monitor.

Via 2-Wire Switch or Management Software (for larger systems):

• Connect the switch to a PC or use its web interface.
• Assign room numbers in bulk.

Importante: Each monitor must have a unique room number. Duplicate numbers will cause call routing errors.

Step 2: Map Outdoor Station Buttons to Apartments

For a 3-button station:

• By default, Button 1 calls Unit 1, Button 2 calls Unit 2, Button 3 calls Unit 3.
• If your numbering is different, configure the mapping.

Configuration methods:

• Via indoor monitor menu: Some systems allow button mapping from the monitor’s settings.
• Via DIP switches or jumpers: Some models use physical switches on the outdoor station to set button addresses.
• Via management software: For advanced systems, assign each button to a specific room number.

Example mapping:

Pulsante	Unit	Room Number
1	Unit 1	101
2	Unit 2	102
3	Unit 3	103

Label each button with the resident’s name or unit number for easy identification.

Step 3: Configure System Settings

• Unlock duration: Set the relay release time (typically 3–10 seconds).
• Ringtone volume: Adjust indoor monitor ringtone volume.
• Video settings: Adjust brightness, contrast, and night vision if available.
• Language: Select the preferred language for the UI.

Step 4: Optional App Configuration (Tuya / Smart Life)

If the indoor monitor supports Wi-Fi and Tuya Smart Life:

1. Connect the monitor to a 2.4GHz Wi-Fi network.
2. Download the Tuya Smart or Smart Life app.
3. Create an account and tap “Add Device.”
4. Follow the pairing instructions.
5. Assign the device to a room and name it (e.g., “Unit 1”).
6. Test remote answering, live view, and unlock.

Nota: Not all 2-wire systems support app integration. Check your specific model’s specifications.

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Testing and Commissioning

After configuration, test every function:

Test	What to Verify
Button 1 call	Rings Indoor Monitor 1 within 1.5 seconds.
Button 2 call	Rings Indoor Monitor 2 within 1.5 seconds.
Button 3 call	Rings Indoor Monitor 3 within 1.5 seconds.
: Fornisce filmati video dei visitatori.	Clear conversation, no echo, no dropouts.
Qualità video	Clear image, correct viewing angle, night vision activates in low light.
Unlock function	Door releases reliably; relay click audible.
Funzioni app	Remote answer, live view, and unlock work over Wi-Fi (if supported).

If any test fails, check wiring connections, cable continuity, and power supply voltage before replacing hardware.

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Risoluzione dei problemi comuni

Problema	Possibile causa	Soluzione
Apartment does not ring	Wrong room number	Reconfigure room number on indoor monitor
	Wiring fault	Check 2-wire connections at switch and monitor
Multiple monitors ring at once	Duplicate room numbers	Assign unique numbers to each monitor
No video	Loose cable	Re-seat 2-wire connections
No audio	Volume muted	Check volume settings
Unlock fails	Relay wiring	Verify lock power and relay connections
App not connecting	Wi-Fi on 5GHz	Switch to 2.4GHz network
Monitor does not power on	Insufficient power	Check 2-wire switch power supply

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Best Practices for 3-Button Systems

• Use quality cable – ≥0.5mm² copper for 2-wire runs.
• Keep cable runs under 100 metres – for longer distances, use thicker gauge or a repeater.
• Avoid parallel runs with power lines – prevents interference.
• Label both ends of every cable – simplifies maintenance.
• Test each apartment after configuration – call from the outdoor station and verify all functions.
• Secure outdoor connections – use waterproof gel caps or silicone.
• Document room numbers and wiring – essential for future service.
• Update firmware – check for updates after installation.

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Why Choose FARHD for Your 3-Button System?

FARHD has been designing and manufacturing video intercom systems since 1998, with over 28 years of industry experience. Our 2-wire systems are trusted in over 100 countries for their reliability, ease of installation, and robust feature set.

Key advantages:

• Source factory – Factory-direct pricing, full quality control.
• 2-wire simplicity – Reuses existing wiring, non-polarity, up to 100m.
• 3-button outdoor station – Ideal for small apartment buildings (up to 3 units).
• 2-wire switch – Provides stable power and fault isolation.
• Resistente alle intemperie – IP65 outdoor stations, -40°C to +70°C.
• OEM/ODM/SKD – Custom branding, packaging, and software.
• No MOQ – Start with a sample; scale as you grow.
• Certificazioni globali – CE, FCC, RoHS, IP65, EMC.

Our products are installed in thousands of apartments, villas, and residential projects worldwide.

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Frequently Asked Questions

Q: Can I connect three indoor monitors directly to a 3-button outdoor station without a switch?
A: It is possible for short distances, but using a 2-wire switch is recommended for better reliability and fault isolation.

Q: How do I assign which button calls which monitor?
A: Configure room numbers on each indoor monitor and map the outdoor station buttons accordingly. Most systems default to Button 1 = Unit 1, Button 2 = Unit 2, Button 3 = Unit 3.

Q: What happens if two monitors have the same room number?
A: Both will ring at the same time. Always assign unique room numbers.

Q: Can I add a fourth indoor monitor later?
A: Yes, if the 2-wire switch has available ports.

Q: Does the system work without internet?
A: Yes. Basic calling, video, and unlock functions work without internet. Internet is only required for remote app access.

Q: What is the maximum cable distance?
A: Up to 100 metres with ≥0.5mm² cable. For longer distances, use thicker gauge or a repeater.

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Contact Us for Catalog, Pricing, and Samples

The FARHD 3-button outdoor station with three indoor monitors and a 2-wire switch is the ideal choice for small apartment buildings. With easy 2-wire wiring, simple configuration, and reliable performance, it delivers everything you need for secure, convenient entry.

Contact us today for catalog, pricing, or to request a sample.

📩 Email: [email protected]
🌐 Website: www.farhd.com
📱 WhatsApp: +86 188 2370 9809 / +86 199 2545 1918

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FARHD – Video Intercom Manufacturer Since 1998.

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