Understanding the distinctions between functional earth and protective conductors is vital for fire detection and fire alarm system safety and functionality. The latest technical bulletin from the Fire Industry Association (FIA) shares the critical roles these conductors play, detailing the unique colour coding standards designed to prevent misidentification.
What are the changes?
The standard BS 7671:2018+A2 mandates that functional earth must be identifiable to avoid confusion with other earthing systems. Specifically, it specifies that functional earth conductors should be marked with pink sleeving (as per clause 514.4 & Table 51). This requirement now extends explicitly to fire alarm installations.
This recent amendment ensures that functional earths are easily distinguishable from other conductors. This prevents misconnection—such as inadvertently routing a protective earth through a functional earth cable—and guarantees the correct operation of the equipment they serve.
Previously, BS 7671 required that low-voltage cables be identifiable with pink sleeving. However, fire alarm installations were not specifically addressed, leading engineers to use green and yellow cables. Now, fire alarm installations are classified within low-voltage systems, clarifying the standard and preventing misunderstandings.
Risks of Misusing Functional Earth as Protective Earth
These additions have been made to protect electricians and fire alarm engineers from electrical safety hazards. When both protective and functional earths are sleeved in green and yellow, there is a significant risk of confusion. These updates ensure that different types of earthing are easily and correctly identified, minimising the risk of installation and maintenance errors that could lead to equipment malfunctions.
The protective earth's primary role is to provide a safe path for fault currents to be directed to earth, allowing a large fault current to flow through the line conductor. This rapid fault current flow triggers the protective device to operate quickly, typically within 0.4 seconds. If functional earth is included in this path, high fault currents may pass through fire detection and alarm equipment, potentially causing EMC spikes that damage sensitive electronics. Therefore, a well-designed earthing system that keeps functional and protective earths separate is essential to ensure safety and functionality in electrical installations.
Pink sleeving in practice
The pink-coloured sleeving should be applied to the conductor's insulation, making it visibly distinct from other wires within the electrical installation. This is particularly important in complex systems where multiple types of earthing are present, as it helps technicians and engineers quickly identify and correctly handle the functional earth conductors. This is especially relevant in fire detection and fire alarm systems, where extra-low voltage (ELV) circuits also require functional earths to be identified with pink sleeving to ensure clarity and proper function of these critical safety systems.
This technical bulletin from the FIA Has been released to provide fire alarm engineers with the correct knowledge about which cables should be used, ensuring the integrity and safety of your fire safety systems.
By following these guidelines, outlined in BS 7671 and BS 5839-1, you can ensure the integrity and safety of your fire safety systems.
Written by Illumino Ignis, technical specialists in the design, supply, and support of safety products.
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