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Author: Michael Publish Time: 27-06-2025 Origin: Site
KNX bus cable is a type of cable wiring for KNX home and building automation systems. Its task is to provide an interference-free, efficient, and safe communication link between all KNX equipment (like sensors, switches, actuators, and central controllers).
In this detailed guide, we will discuss the cables' technical parameters, cable types, wiring structures, applications, and installation rules to choose or install the KNX bus cables. We will also add the topics: KNX vs. CAT6 pricing and common faqs.
KNX cable (an often used synonym is EIB KNX cable or bus EIB cable), a twisted pair of low voltage communication cables, is the channel for signals communications between devices that operate under KNX protocol. What does the acronym represent? KNX is the language Konnex, which happens to be the international open protocol for home and work control systems.
KNX bus cable, as the name says, the bus cable, enables one to interconnect multiple devices to one communication line, KNX bus. As a result, it dramatically decreases the situation where there is a necessity for individual wiring for point-to-point connection.
• Conductor: Solid bare copper, 0.8 mm wire
• Insulation: PE (Polyethylene)
• Twisted Pairs: 2 pairs (4 wires in all)
• Shielding: With the option of aluminum foil with drain wire for improved EMC
• Sheath: Either LSZH (Low Smoke Zero Halogen) or PVC
• Color Code:
Pair 1: Red & Black (bus communication)
Pair 2: White & Yellow (protected/spare)
Item | Specification |
Operating Voltage | ≤ 100 V |
Test Voltage | ≥ 800 V |
Impedance | 100–120 Ohm |
Capacitance | ≤ 100 nF/km |
Temperature Range | -20°C to +70°C |
Min. Bending Radius | 8× cable diameter |
Bus Segment Length: Max is 1000 meters
The distance from Power Supply to Device is horizontally extended: Max is 350 meters
Max Devices per Line: 64 (can expand with line couplers)
Max Number of Lines per Installation: 15, including a main line
Never go with a star topology. The best option for KNX system connection is bus or tree topology.
KNX uses a two-wire bus system with free topology (linear, tree, or star—with limitations). Essentially all devices are connected in parallel (or branch out) to the same bus cable.
Add tool-free push-in connectors to KNX devices.
Terminate shielding by option in high EMC areas.
KNX cable connector kits can be used in panels or junction boxes.
KNX bus cable is the general wiring solution in:
Smart homes – lights, curtains, HVAC systems
Commercial premises – control energy, and room automation
Hotels – smart keys for rooms, lighting scenes
Hospitals – ward requirements, access controls
Industrial buildings – monitoring, automation, energy efficiency
This question is pretty popular among designers, but the practice of connecting CAT6 cable to KNX systems is not recommended to use unless it is a test ground or hybrid environment.
Feature | KNX Cable | CAT6 Cable |
Twisted Pair | 2x2x0.8 mm² | 4x2x23 AWG |
Certification | KNX Certified | Not KNX-compliant |
Protocol Optimized | Yes | No |
Sheath | LSZH/PVC | Often PVC |
Use in KNX | ✅ Recommended | ⚠️ Not Certified |
Conclusion: CAT6 is a cable for high-speed Ethernet, while the KNX cable is a specialized cable for automation. Having the correct cable means safety, compliance, and the constant integrity of the signal.
Type | Approx. Price (USD/m) |
Unshielded PVC | $0.30–$0.45 |
Shielded PVC | $0.50–$0.70 |
Shielded LSZH | $0.70–$1.20 |
Halogen-Free + Fire Rated | $1.20–$1.60 |
Prices vary by brand, MOQ, jacket material, and export packaging. For large building projects or OEM/ODM, bulk discounts apply.
KNX cable certified pass through the requirements of:
KNX Association – Specifications to TP1 interface
IEC 61131 / EN 50090
CE / RoHS / CPR depending on market
Low Smoke Zero Halogen (LSZH) for public buildings
Flame Retardancy: IEC 60332-1 and above.
Before using any KNX cable, one must check the cable datasheet or label for compliance.
Use shielded cable near high EMI areas (these include power lines and motors)
The distance should be at least 10 cm from high voltage cables
Employ LSZH jacket when in public places with confined spaces
Take the time to choose the right bus connectors specific for KNX protocol
Mixing CAT5/CAT6 with KNX wiring
Using star topology instead of tree or bus topology
Overloading one segment (>64 devices)
Ignoring proper EMC shielding when required
Q1: Abbreviated to what may mean Konnex?
A: KNX stands for “Konnex,” an evolution of EIB (European Installation Bus) standard. In other words, KNX bus cable = Konnex communication cable.
Q2: What is the difference between KNX and EIB cable?
A: They are functionally the same. EIB is the predecessor of KNX. “Cable KNX EIB” is often used to refer to older labeling. Modern systems use KNX-certified cables.
Q3: Can one opt for CAT6 for KNX wiring?
A: Though it is technically possible, it is not advisableto use CAT6. Such cable can hardly be classified as KNX compliant and is not made of flame retardant material with an exact impedance value which is mandated by KNX protocol for TP1 signals.
Q4: How many devices comprise KNX bus cable (line)?
A: 64 devices max per line. Many are more easily added by using couplers and power supplies.
Q5: What about shielding cables?
A: Shielding is not compulsory, yet advised in environments of high interference (factories, places where power lines are etc.).
Model | Type | Shielding | Outer Sheath | Use Case |
KNX-TP1-2x2x0.8 | Twisted Pair | No | PVC | General indoor wiring |
KNX-TP1-SH | Twisted Pair | Foil + Drain | LSZH | Public buildings |
KNX-FR | Fire Rated | Yes | LSZH CPR | Fire-resistant zones |
KNX-UV | UV Resistant | Yes | PE | Outdoor conduit |
A proper and commensurate cable selection plays an integral part in delivering good performance, safety, and scalability of your business from your home to industrial plants.
Keep in mind this 3 rules:
Use TK1 KNX specifically manufactured cable
You should not mix it with Ethernet cable.
Review the datasheets and corresponding standards prior to making a purchase.
Unsure if you need help picking a model or if you need an OEM/ODM service? Don’t think twice, because we are the commercial KNX bus cable supply and custom solution experts.
michael@zion-communication.com
+86 13757188184
