Loose Tube Fibre v Tight Buffered Fibre v CST Fibre v SWA Fibre

17 January 2018

What is the difference between Loose Tube, Tight Buffered, CST and SWA Fibre Optic Cable?

So you’ve got some quotes for a new fibre optic infrastructure – One for a loose tube fibre, one for tight buffered? What even is the difference? Does it matter?

With many options on the market, we often get questioned on what the difference is and why you should choose one over another. There are many types of fibre cable on the market, time to eliminate the confusion and to help give the insight behind the choices we make.

Why Tight Buffered Fibre?

Tight buffered fibre is available in both single mode and multimode fibre types. It is most commonly found within buildings and connecting remote cabinets back to your main server room. Out of all fibre optic cables, it is the simplest to install and terminate, this allows for a cost saving on the labour making is cheaper; however, this is for a good reason. When compared to many of its siblings, it doesn’t offer much concerning protection.

With the cable, you get an external low smoke, zero halogen sheathing enclosing the typical kevlar type material inside, this aids in providing a small amount of resilience against damage. Encompassed within this kevlar type material is the fibre optic cores enclosed within a tight buffer sheathing.

Due to the lack of any strengthening members, tight buffered fibres are very flexible in comparison to CST and SWA fibres; this makes it excellent for internal installations.

Pros:

  • Quick and easy installation that allows for cost savings
  • Flexible cable to allow for installation
  • Cost

Cons:

  • Not water resistant

Why Loose Tube Fibre?

Loose tube fibre is most often used in external environments. Like it’s tight buffered counterpart, it comes complete with an external low smoke, zero halogen sheathing, underneath this lays the typical kevlar material that provides a small amount of resilience against damage but also proves as a way of strengthening the fibre.

This, however, is where the changes are visible, underneath the kevlar material lays another tube, this tube lays loose within the outer sheathing protected by the kevlar. Inside that tube lays the fibre optic cores, the fibre cores lay within a water repellent gel that serves as a barrier against the elements. This gel stops water penetrating through and causing damage to the actual fibre cores.

In external environments with the constant changes in temperature and moisture levels, it is essential that the cable is suited.

The combination of the fibre optic cores ability to freely move within the gel and kevlar reduces the risks of stress fractures and the moisture repellent properties of the gel ensure that the fibre optic cable can withstand the external elements for years to come.

Pros:

  • Suitable for both indoor and outdoor applications
  • Water resistant

Cons:

  • The water-resistant gel means a messy and longer termination time
  • No protection from rodents and crushes

Why Corrugated Steel Tape (CST) Fibre?

Corrugated Steel Tape, CST for short is a loose tube fibre optic cable that has been enclosed within further protection. It keeps an external low smoke zero halogen sheathing but under this lays an armoured barrier.

Suited to external runs that are enclosed within areas where rodents are a worry due to its nature it is more likely found on campus backbones. It is also suited to warehouse environments where there is a higher chance of the fibre cable being crushed.

Pros:

  • Rodent and Crush Resistant
  • Water Resistant

Cons:

  • Higher cost
  • Not flexible
  • Longer times to install and terminate

Why Steel Wire Armoured (SWA) Fibre?

If you fear the CST might not cut it, then it’s bigger brother indeed shall.

Keeping the most external sheathing as low smoke zero halogen, SWA is still able to be run within internal environments, however, once inside this you are met with 0.9mm thick galvanised wire, this protects the loose tube fibre inside from even the most determined rodents. You are then met with something that bears a resemblance to the standard loose tube fibre optic cable, a further LSZH sheathing in which a kevlar type material is found protecting the loose tube.

Pros:

  • Remarkably resilient to rodents and water ingress
  • Still suitable for internal cable routing
  • Able to be directly buried without the need for ducts installing

Cons:

  • Increased time to install due to lack of flexibility
  • Large containment required due to bend radiuses and cross-sectional area
  • Increased time to terminate due to water repellent gel and thick galvanised wire

Specialist Fibres?

With fibre being such a common choice of backbone cabling, it’s no surprise there’s a requirement for specialist fibre optic cables. There are a variety of cables to fulfil the full range of needs.

Fire Resistant Fibre Optic Cabling

Ideal for interlinking critical security systems that are required to be active in the event of a fire. Offered in a variety of options, covering single mode and multimode, unarmoured and CST.

Marine Grade Fibre Optic Cabling

With fibre being the choice for long-haul communication, it makes perfect sense for off-shore uses. Marine Grade Fibre takes a standard loose tube fibre cable and protects it with a steel tube and galvanised steel wires.

Still Need Re-Assurance?

Every installation is different, with so much to take into consideration when making an important choice it’s very common not to know the best course to take.

When planning a fibre optic installation, our design teams will work closely with you to establish your current and future requirements to ensure the installation fits your needs for the foreseeable future. If you need a fibre optic cabling, get in touch with us either via our live chat or call and speak to one of our experts on 01604 422722.