A guide to the different KNX cables

Here is a quick and simple guide to show which cable to use for what purpose in a KNX system. 

TP1 - (White or Green) KNX cable (also known as TP1 cable)

• Features two twisted pairs of solid conductor with a foil screen and tinned copper drain wire in a green LSHF or PVC jacket. 
• It has been tested and certified as being suitable for use in KNX systems and bears the KNX logo and is available in 200m or 500m rolls. 
• In general, 'Green cable' is used for ALL KNX Bus wiring and the White version is useful for running along skirting boards etc. It is also helpful when for example wiring for door communication or anything that requires KNX cable but is not a BUS device. 
• Use this cable for ALL installations unless you have a specific requirement that one of the other cables here covers. 

1 Pair – (Green)

• Similar in construction to the standard 2 x 2 x 0.8mm, the one pair version features a single twisted solid conductor pair with a foil screen in a green LSHF jacket. 
• The cable benefits from being smaller, lighter and offers savings on both space and cost. It is also ideal as a jumper cable where its greater flexibility and reduced diameter makes it more suitable than the 2 pair. 
• It is available in 100m or 250m rolls
• Flexibility is the key thing here. Use this cable for rack wiring. 

Duct Grade TP1 (Black) KNX cable

• Essentially the same as TP1 cable but sheathed in a tough, black, UV resistant polyethylene (PE) waterproof jacket over the standard LSHF inner sheath.
• Available in 300m rolls.
• The clue is in the title, use this within wiring ducts and trays. Also used for external runs where UV resistance is required.

Steel Armoured Exterior Grade (Black) KNX cable 

• Again, TP1 cable but housed in a tough, PE inner sheath and 0.9mm solid galvanised steel wires cased in a heavy waterproof PE jacket. 
• Ideal for installations where physical damage, vandalism or rodent attacks are possible or for direct burial in the ground. 
• Available to purchase by the meter.
• Use for direct burial or any situation where damage could occur. 

LU approved (Green with White stripe) KNX cable 

• The LU approved KNX cable has passed the latest London Underground requirements and has been independently tested by the BRE-Global Ltd (Building Research Establishment). 
• It can be identified by the distinctive white stripe over the green sheath. 
• Use for ALL London Underground applications.