What Is LI2Y(St)CH Cable? Halogen-Free PIMF Signal Cable Selection
LI2Y(St)CH cable is a data and signal cable with PE-insulated twisted pairs, each foil shielded, an overall copper braid and a halogen-free outer sheath.
LI2Y(St)CH cable is a data and signal cable whose polyethylene (PE) insulated cores are twisted into pairs, each pair individually foil shielded, with an overall copper braid shield and a halogen-free outer sheath. It is used in buildings and facilities that require halogen-free cable, on low-capacitance lines for serial communication, measurement data and links between automation devices.
What does the type code mean?
- LI: fine-stranded, flexible copper conductor.
- 2Y: PE core insulation. Because PE has a lower dielectric constant than PVC, the capacitance between cores is lower and the signal degrades less over a long line.
- (St): foil shield. The PIMF suffix shows that the foil is wrapped around each pair separately, which reduces crosstalk between pairs.
- C: overall copper braid shield around all pairs.
- H: halogen-free outer sheath.
- The +0.22 or +0.50 in the product name: the cross-section of the drain wire that provides the connection to the pair shields.
LI2Y(St)CH and related types
| Type | Core insulation | Shield | Outer sheath |
|---|---|---|---|
| LI2Y(St)CH-PIMF | PE | Foil on each pair + overall braid | Halogen-free |
| LI2Y(St)CY-PIMF | PE | Foil on each pair + overall braid | PVC |
| LIH(St)CH | Halogen-free compound | Foil + braid | Halogen-free |
Selection criteria
- Halogen-free requirement: If the specification requires halogen-free cable, the PVC-sheathed CY type is not a substitute for this cable. If there is no such requirement and the line does not need low capacitance, LIH(St)CH or PVC types offer a wider choice of sizes.
- Number of pairs: Allocate one pair to each communication or measurement channel and leave one spare pair.
- Cross-section: 0.22 and 0.50 mm² are for data and measurement signals. On long lines, or if one pair carries device power, choose 0.75–1.5 mm² according to voltage drop.
- Electrical values: Birtaş product data gives a maximum capacitance of 120 nF/km and an outer sheath of halogen-free flame-retardant (HFFR) compound to EN 50290-2-27. Compare the impedance and capacitance required by the communication device with the manufacturer's datasheet.
Common mistakes
- Splitting pairs: The two cores of one signal (for example A and B in RS-485) must go on the same twisted pair; with cores taken from different pairs, the twist and the pair shield are of no use.
- Trying to connect the foil shield directly: The connection to the pair shields is made through the drain wire.
- Earthing the shield at both ends at random: A ground loop causes measurement errors; earth the shield as instructed by the device manufacturer.
- Running it in the same duct as power cables: The shield reduces interference coupling but does not eliminate it.
LI2Y(St)CH cables in the catalog
All 9 active products in the LI2Y(St)CH Signal Cables category are from the Birtaş Kablo LI2Y(St)CH-PIMF series; they are sold by the metre and on quotation:
| Core cross-section | Number of pairs | Drain wire |
|---|---|---|
| 0.22 mm² | 2, 3, 4 | 0.22 mm² |
| 0.50 mm² | 2, 3, 4 | 0.22 mm² |
| 0.75 mm² | 2 | 0.50 mm² |
| 1 mm² | 2 | 0.50 mm² |
| 1.5 mm² | 2 | 0.50 mm² |
For other types, see the Signal Cables category.
Frequently asked questions
What is the difference between LI2Y(St)CH and LI2Y(St)CY?
The core insulation and shield construction are the same; only the outer sheath differs. CH is halogen-free, CY has a PVC sheath. CY is not used in projects with a halogen-free cable requirement.
What does PIMF mean?
It shows that each twisted pair is shielded with its own metal foil. This reduces signal crosstalk between the different channels in the same cable.
How is the shield earthed?
On analogue measurement lines, the pair shields are usually earthed at one end to prevent ground loops. The overall braid may need to be connected at both ends against high-frequency interference; follow the device manufacturer's instructions.
Can it be used on an RS-485 line?
Its twisted, individually shielded pair construction suits serial communication. Choose it by comparing the characteristic impedance and capacitance required by the line with the device datasheet.