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When it comes to copper cabling, choosing the level of shielding you want the cable to have can prove a minefield of confusing acronyms and perplexing industry technology. We’ve put together this handy guide to help you understand the meaning of some of the most common terms.

The shielding inside your cable acts as a barrier to protect the cable from electromagnetic interference (EMI), radio frequency interference (RFI) and crosstalk between pairs and adjacent cables. It also prevents the signal from the cable interfering with surrounding equipment. The various levels of shielding offer a range of different advantages suitable for a number of applications.

U/UTP: UNSHIELDED TWISTED PAIRS

Also known as UTP, this is currently the most common and basic method of cable construction, consisting of pairs of wires twisted together. There is no shielding, instead the symmetrical twist in the wires create a balanced transmission line, helping to reduce electrical noise and EMI. In addition, the different twist rates of each pair can be used to reduce crosstalk. In higher category cables, a cross-web filler may be found separating the individual pairs to help reduce alien crosstalk from adjacent cables.

F/UTP: FOILED WITH UNSHIELDED TWISTED PAIRS.

Often referred to as FTP, this type of cable features an overall foil shield wrapped around unshielded twisted pairs and a drain wire. When the drain wire is correctly connected, unwanted noise is redirected to ground, offering extra protection against EMI/RFI.

S/UTP: SHIELDED WITH UNSHIELDED TWISTED PAIRS.

This cable construction has an overall braid screen with unshielded twisted pairs. This cable is often referred to as an STP, however this term should be used with caution due to other shielded cables also using this term. Always check whether the cable will have any shielding and whether individual pairs have their own shield. The cable is capable of supporting higher transmission rates across longer distances than U/UTP and provides better mechanical strength and grounding due to the braid.

SF/UTP: SHIELDED AND FOILED WITH UNSHIELDED TWISTED PAIRS.

This cable has both an overall braid shield and foil shield with unshielded twisted pairs. This cable offers effective protection from EMI both from the cable and into the cable as well as much better grounding due to the additional braid.

U/FTP: UNSHIELDED WITH FOILED TWISTED PAIRS

This type of cable has no overall shielding but the individual twisted pairs are wrapped in a foil screen, offering some protection from EMI and crosstalk from adjacent pairs and other cables.

F/FTP: FOILED WITH FOILED TWISTED PAIRS

This type of cable features an overall foil shield with individually foil tape shielded twisted pairs. These are similar to F/UTP cables, with the addition of a foil shield around each twisted pair. The cable construction is designed to provide the assembly with greater protection from crosstalk from adjacent pairs and other cables, RFI and EMI.

S/FTP: SHIELDED WITH FOILED TWISTED PAIRS

Similar to F/FTP, the individual twisted pairs are wrapped in a foil tape before being wrapped in an overall flexible yet mechanically strong braid screen. The additional foil on the twisted pairs helps to reduce crosstalk from adjacent pairs and other cables. The braid provides better grounding.

SF/FTP: SHIELDED AND FOILED WITH FOILED TWISTED PAIRS

Offering the maximum protection from RFI/EMI, crosstalk and alien crosstalk, this cable has both an overall braid shield and foil shield, with individually foil tape screened twisted pairs. This type of cable provides the best level of protection from interference and better grounding due to the braid.

Common Industry Acronyms	ISO/IEC11801 Name	Cable Shielding Type	Twisted Pair Shielding Type	Example
UTP	U/UTP	None	None
FTP, STP, ScTP	F/UTP	Foil	None
STP, ScTP	S/UTP	Braiding	None
SFTP, S-FTP, STP	SF/UTP	Braiding & foil	None
STP, ScTP, PiMF	U/FTP	None	Foil
FFTP	F/FTP	Foil	Foil
SSTP, SFTP, STP, PiMF	S/FTP	Braiding	Foil
SSTP, SFTP	SF/FTP	Braiding & foil	Foil

Reference: universal networks

LSZH—Short for low smoke zero halogen, LSZH is a kind of cable built with a jacket material free from halogenic materials (such as chlorine and fluorine), since the toxic nature of these chemicals when burned. The term “low-smoke, zero-halogen” describes two distinct properties of a cable compound. The term “low- smoke” describes the amount of smoke which a compound emits when burned, while “zero-halogen” describes the amount of halogens used to make the compound. Terms like LSOH, LSHF and LSNH are all proper references for cables possessing low-smoke and zero-halogen properties.

PVC—Polyvinyl chloride (vinyl), a general-purpose plastic jacket material used for cables. Features low in cost and flexible, PVC cable is widely used in applications such as computers, communications and low voltage wiring. In the world of cabling, “PVC” is often used to denote a cable that is not suitable for use in a plenum airspace. PVC can potentially be dangerous in a fire situation, releasing heavy smoke and hydrogen chloride gas, which poses a great threat to human health electronic devices. PVC cables often have a CM, CMG, or CMR rating as defined by the National Electrical Code (NEC).

Differences Between LSZH and PVC Cable

Judging from the physical appearance, the difference between LSZH and PVC cable is very distinct. A PVC cable feels soft and it is smooth, whereas an LSZH cable feels rough since they contain the flame retardant compound and it is stiffer. LSZH cables are more aesthetically appealing than PVC cables. In addition to this, LSZH cable differs from PVC one in at least three aspects:

Cost: LSZH cables are slightly higher in cost than some PVC cables, but they are much safer when it comes to human health and sensitive and expensive electronic equipment. And this should be considered when comparing the cost.

Flexibility: Comparing with PVC compounds, there is a limited range of compound flexibility available for LSZH compounds, so LSZH cable is not recommended for robotic or continuous flex applications.

Heat: When a PVC cable is set on fire, it emits chemical fumes, acids and other toxic gases, which are both corrosive and harmful to human beings and environments. As for LSZH cable that has a flame-resistant jacket, it doesn’t emit these chemical substances even if it burns or exposed to high sources of heat. And it can reduce the amount and density of the smoke.

When Do I Use LSZH or PVC?

It is feasible that LSZH and PVC have equally effective performance in modern buildings. So the decision on which one to choose actually depends on the situation, that is to say, where you are going to run the cable.

PVC cable has been used in built environment for power and control applications for decades. It is commonly used for horizontal runs from the wiring center, or for vertical runs between the floors—but only if the building features a contained ventilation system running through the duct work.

LSZH cable would be more appropriate for places where fire presents a hazard to occupants. We known that the primary danger in the event of a fire is not the fire itself but the smoke and gas produced. Therefore, it is vital that the materials and products that are installed contribute as little smoke and gas as possible when burnt. LSZH cable can be employed in the following situations:

Confined spaces with large amounts of cables in close proximity to humans or sensitive electronic equipment, such as submarines and ships.
Mass transit, central office facilities and telecommunication applications.