Voltages on Fermax Duox Plus: what they mean and how to interpret them
One of the key aspects of correctly diagnosing a DUOX PLUS installation is understanding and interpreting the line voltages . At ProFermax , many technicians ask us what values should appear in an installation and what it means if they don't match. In this article, we explain the typical DUOX PLUS voltages and how to use them to detect potential faults .
🔍 Why is it important to measuretension on DUOX PLUS?
The Fermax DUOX PLUS system works with just two non-polarized wires that transmit data, audio, video, and power . Therefore, the voltage across these wires provides valuable clues about the status of the installation.
Measuring the voltage at different points on the BUS is a recommended practice for:
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Verify that the devices receive signal and power.
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Detect voltage drop problems due to poor wiring or excessive load.
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Identify short circuits, connection errors or faulty terminals.
Typical voltages in a DUOX PLUS installation
Below is a guide to common voltage values you should expect in different situations and system components:
| System status | Expected voltage between the BUS wires |
|---|---|
| No terminals connected | Between 23-26 VDC |
| Terminal (monitor or phone) in standby | Between 15-18 VDC |
| Active call from panel | It drops to about 12-14 VDC |
| Active communication (audio or video) | It can range between 10-14 VDC |
| System overloaded or faulty | < 10 VDC or reading instability |
🛠️ ProFermax tip: always measure with a multimeter in direct current (VDC) between the two BUS wires, without disconnecting them.
🧰 What to do if the voltages are not correct?
If the tensions are outside the normal range, action must be taken:
🔻 Constant low voltage (<12 VDC)
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Possible voltage drop due to poor quality cable or insufficient section.
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Too many terminals in the facility without additional power.
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Use of aluminum cable or mixtures of sections.
👉 ProFermax Solution: Check the wiring type and cross-section. If necessary, install an additional Fermax Ref. 4840 power supply or a Fermax Ref. 3268 regenerator to divide the load.
🔄 Unstable or erratic tension
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There may be an intermittent short circuit , a damaged terminal , or poor contact.
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Check connections, terminals or possible damage to the wiring.
👉 Disconnect areas piecemeal until the fault is isolated. Use the Fermax Ref. 9419 decoder if you need to isolate apartments individually.
✅ Conclusion
Monitoring the voltages in a DUOX PLUS installation is essential to ensure its proper functioning. At ProFermax, we recommend:
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Always measure when installing and performing maintenance.
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Check that the values are within expectations.
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Do not hesitate to use Fermax regenerators or additional power supplies if you detect a voltage drop.
📞 And if you have any questions, please contact our technical team. At ProFermax , we have all the products and support you need to ensure your installation always operates at 100%.