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Cabling Fire Safety: Everything You Need to Know

9th May, 2018

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This blog post is about cabling considerations to be taken into place for fire safety. Find out more about ACCL’s data cabling services here.
 
Cabling fire safety is one of the most critical elements of modern office and residential buildings.
 
Many office buildings in London and the UK accommodate hundreds or thousands of people, and ensuring they are safe in the event of fire is not only a moral imperative for the employers but, under most circumstances, a legal obligation.

 

We get a great deal of questions related to cabling fire safety from our clients, especially in light of the new requirements regarding cabling assemblies in fire escape routes (introduced in 2015) and the new CPR regulations (whose coexistence period has ended in July 2017, less than a year ago).

 

We hope this material will be of use to anyone who wants to gain an understanding of general London fire safety requirements for data cabling, of what you need to do in order to comply with these requirements, and of the general technical and legal implications that modern fire safety practices have.

 

Fire Safety: the Basics

 

Fire safety, as we understand it today, has three basic aspects:

 

  • Fire prevention — that is, ensuring that no fires can be started accidentally or (within reasonable margins, and under specific conditions) even intentionally
  • Fire control — ensuring that, if a fire does start, it does not burn uncontrollably and that it can be put out as quickly as possible
  • Evacuation and intervention safety — ensuring that, if firemen need to intervene and evacuate people, they can do so safely, as long as they take a set of known precautions.

 

Fire Prevention and Control

 

Fire prevention and control measures are closely intertwined. They aim to ensure that fires do not start in the first place, and that if a fire does start nonetheless, it remains localized and can be put out as quickly as possible.

 

Fire prevention and fire control measures are distributed uniformly throughout a data cabling installation. These measures range from choosing specific types of cables and materials to adhering to various installation requirements.

 
EU Cable Fire Safety Regulations

Evacuation and intervention safety measures are mainly clustered around fire escape routes. These measures are critical as they often provide the last barrier against loss of life in case of major incidents. In fact, the regulatory requirements that define them have been adopted after the very unfortunate experience of such incidents.

 

Data cables typically end up burning through contagion (i.e. the fire is kindled from nearby sources), but exceptions are not unheard of, especially in outdoors deployments, which can be vulnerable, among others, to lightning.

 

In both cases, though, it is primarily the cable’s insulating sheathing that kindles and carries the fire.

 

This suggests that there are two ways to prevent and control fires in our cabling systems: installing cables as far away from potential sources of fire as possible, and using cables whose insulation is not easily flammable.

 

 

Cable installation guidelines therefore recommend that cables be installed away from any potential sources of open flame or sparks, and far from high-temperature installations and objects.

In certain situations, London cable installers may also use various fire stop solutions, such as sealants or metal sheaths and conduits. These act as fire barriers, insulating the cables from outside fires or, if the cable itself is burning, insulating nearby object from the burning cable.

 

Fire rated cabling
 

Cable fire safety regulations have recently been updated, throughout the EU and in the UK, and now mandate cable manufacturers and resellers to be more transparent about the cables’ fire performance.

 

Under this new set of regulations, known as Construction Products Regulation (CPR), manufacturers are now required to subject their cables to testing, which results in four ratings being given, for the following characteristics:

 

  • Flammability (ratings range from Class A, or ACA, to Class F, or FCA; Class A is the best)
  • Smoke production (ratings range from s1 to s3; s1 is the best)
  • Flaming droplets (ratings range from d0 to d3; d0 is the best)
  • Acidity (a1 to a3; a1 is best)

 

In addition to these ratings, UK constructors and cabling engineers also use a classification based on smoke emission and halogen content. Safe ratings for use in office and residential buildings include LSHF, LSOH, OHLS and LSNH, all of which have low fire hazard.

 

In the UK, there is no legal requirements to use cables of a certain CPR rating for a given purpose, but a broad framework is laid down by BS 7671, and industry bodies, such as the British Cable Association (BCA) issue their own guidelines.  These guidelines include:

 

  • Using cables rated class E or higher, and/or rated LSHF, LSOH, OHLS or LSNH.
  • Avoiding class F cables
  • Ensuring that only cables with known rating are deployed
 
 
 
 
 

Fire Escape Cabling: Evacuation and Intervention Safety Concerns

 

When we talk about fire prevention and control, we are mainly looking at normal, or at least predictable situations, where cabling systems are not exposed to extreme temperatures, nor to viciously-burning open flame.

 

This is not the case when it comes to evacuation and intervention. When people need to be evacuated and firemen need to intervene, the ambient conditions are entirely different.

 

Even when they are not themselves on fire, studies have shown that cables and support systems can be subjected to temperatures as high as 300-500 degrees Celsius. At these temperatures, some materials, especially plastic, readily degrade, collapse and burn. This has turned out to be a major problem, with tragic consequences. Between 2005 and 2010, four firemen died, in Stevenage and, respectively, Southampton, after the cables in access routes fell down and trapped them.

 

These tragic incidents prompted authorities to update building standards and cabling fire safety regulations, which now require that “wiring systems in escape routes shall be supported such that they will not be liable to premature collapse in the event of fire”.

 

To understand the practical consequences of these regulations, there are two aspects that we need to understand: what constitutes an escape route, and *how* the adequate level of support can be provided.

 

Fire safety cabling
 

An escape routeis any route that can be used to escape to a place of safety during an emergency.Escape routesinclude both designated escape routes, such as corridors and hallways, but also open areas through which one may be reasonably expected to pass on their way to a safe place.

 

Cabling support mechanismssuch as heat resistant cable trunking, conduits, trays or casings installed in these areas need to remain able to support the cabling even under the sort of thermal stress that an open fire involves. In practice, this means largely that:

 

  • Cables in these areas must be supported by metal supports with adequate fire resistance properties.
  • All fixing elements on which cable management systems rely, such as wall plugs, must have adequate fire resistance properties

 

These regulations apply to all types of cabling. Furthermore, the cabling itself is taken to mean not only the cables themselves, but any busbars and parts which secure and enclose the cable or busbars.

 

You should bear in mind that the escape routes themselves are not set in stone.

 

The designated fire escape routes have to be assessed, and then updated whenever the need arises. In practical terms, this means that you need to:

 

  • Ensure compliance when the cabling system is installed or upgraded
  • Audit and, if needed, upgrade the cabling system whenever the designated fire escape routes change, so as to account for new fire escape routes.

 

Evacuation plan for fire
 

In practical terms, regulations specific to fire escape routes rule out the use of plastic support systems and components in fire escape areas. Stainless steel supports are the most common recommendation, as stainless steel can easily withstand the high temperatures present during a fire, degrades slowly with time, and is easy to integrate in the landscape of any modern building.

 

Outside fire escape routes, there are no specific legal requirements (other than the ones we talked about in the previous section). Cable management systems and support systems made from less fire-proof materials can be used in these areas, but we recommend that you make a decision on a case-by-case basis.

 

Plastic components are cheaper and easier to install, so they are a viable choice. Using metal fixing in areas near the escape routes, however, can be highly beneficial, even though it may not be legally required.

 

The right team of London cabling specialists can help you choose the right materials and the right types of cables for any building or office. At ACCL, we make your safety our priority, so all our advice will take into account current UK cabling fire safety recommendations and regulations.

 

How do installers ensure compliance with UK fire escape cabling requirements? The foundation of design decisions is a thorough survey of the installation environment. This survey aims to establish:

 

  • The designated escape routes
  • Mechanical and material properties of escape route elements (such as wall thickness and material)
  • Areas of interest in the immediate vicinity of escape routes

 

Based on this data, cable installers can choose the optimum support and fixing elements, and make recommendations about other areas as well.

 

How Can You Ensure Continuous Compliance with These Requirements?

 

We recommend:

 

  • Auditing the wiring installation in designated fire escape routes whenever the escape routes in your London building are changed.
  • Periodically auditing the support and fixing systems in designated escape areas. While these systems are sturdy, they are nonetheless susceptible to manufacturing flaws, and some fixing components, such as wall mounts, still rely on the integrity of surrounding wall sections in order to provide adequate levels of support.

 

cable-audit
 

Conclusions and recommendations

 

Ensuring the safety of your staff, clients and collaborators, as well as the safety of firemen, paramedics and other personnel is a legal requirement for businesses, and an obligation for all of us.

 

A wide range of measures are available in order to ensure the level of safety that we should aspire to in this day and age:

 

  • Installing cables conservatively, keeping them safely away from potential fire sources
  • Using adequate cables throughout the office area
  • Ensuring that cables in fire escape routes are properly supported, even in case of fire

 

Cabling fire safety can prove to be complicated, especially if you don’t have the necessary experience.

 

At ACCL, we have been in this business for more than 20 years, so we have seen these standards and requirements change and evolve.

 

Thus, we can also foresee how the rules will change in the upcoming future. Our goal is to make sure all our clients’ places of business are safe, along with all their personnel.

 

If you’re looking for future-proof solutions that comply with cabling fire safety regulations, we’d love to help.

 

Give us a call or drop us a line and we’ll set a time and date for your FREE, no-obligations site survey.

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