Cabling Conundrums: Understanding Cable Fire Safety Standards
Take a minute to stop and think about all the typical items in your place of work that are considered a fire risk. Now think about all the items that have to meet standards to be safe for use. Did you consider all the cabling in the walls and ceilings?
Since the Grenfell Tower fire in 2017, strict standards have been put into force to ensure companies are producing products that are safe for use and pose no additional fire risk. You may have heard how this applies to household appliances but how does it affect cabling?
In November 2017 an amendment to cabling industry standards was released and put into force to ensure that cables used in structures posed no additional fire risk. Strict tests were designed to determine the categories that each cable would fall into. The table below details the different categories:
To determine the grading of each cable vigorous tests are undertaken to separate the properties in terms of safety.
Smoke production is determined by a 20-minute test that consists of a length of cable being attached to a vertical ladder with a flame applied at the base. This test aims to evaluate the cables potential to obstruct vision when burning. An S1 cable will produce a total of 50 meters squared of smoke at a rate of 0.25 metres squared per second. The S2 rating produces less than 400 metres squared of smoke at a rate of 1.5 metres squared per second. The a and b ratings are determined by the density/opacity of the smoke produced. Smoke that has a strong opacity receives an A rating while thicker, denser smoke receives a b rating. If less than 60% of a light source can be viewed through the smoke the cable fails the test and is deemed not satisfactory for industry standards.
The next test determines the acidity of elements used within the cable and therefore the potential to burn and produce harmful gases. A cable with a rating of A3 has a pH value of less than 4.3 and deemed more of a risk than an A1 cable with a pH level of no less than 4.3.
The third test looks at the cables potential to separate and flame for a period of time. The test is 20 minutes long and observes how the cable separates and burns to determine the fire risk. D0 means
no material separates and burns. D1 indicates that particles separated for no longer than 10 seconds. D2 advises that particles separated and burned for more than ten seconds.
Different graded cables are used in different applications. It is important that clients understand cable grading so they can work with the installer to recognise the needs of their project and select the correct classification of cable to reduce additional fire risks and meet the preferred standards of the industry.
If you’d like to read more about the changes to cabling standards please click here to find various reading material.
Should you prefer a visual explanation, you can view EXCEL cabling’s YouTube series here.