Electrical Safety First’s recent electrical installation safety roundtable focused on open-circuit PEN conductors, which serve as both a protective earthing and neutral conductor. Although PEN conductors within installations have been prohibited for some time now, older ones still remain in, for example, the rising mains in blocks of flats and military camps.
When the PEN conductor fails, not only does this present a shock hazard but the diverted neutral current can also create a significant heat build-up, as it typically makes a circuit via exposed metalwork (such as gas, water and oil pipes, etc.) – which can then lead to fire.
Data obtained from the Health and Safety Executive shows at least one incident of an open-circuit PEN conductor is reported every day - with around 10% of them leading to injury. But as many incidents go unreported, it’s believed the real figure could be significantly higher.
“Anecdotal evidence suggests that open-circuit PEN conductors might be a growing problem due to a range of factors – including our ageing distribution system, metallic service pipes being replaced and the theft of copper from cables”, explains Martyn Allen, Technical Director at Electrical Safety First.
“The Charity is committed to promoting collaborative working and, while electrical distributors are legally required to ensure the safety of the electrical distribution network, we believe that the electrical installation sector can also help reduce the risk that open-circuit PEN conductors can present.”
This opportunity to help mitigate the risk has also been recognised and considered by the Committees responsible for developing the 18th Edition of the IET Wiring Regulations. Requirements for foundation earthing, supplementary earth electrodes and over-voltage detection/protection devices may be included in the draft for public comment (DPC) to BS 7671: 2018 (18th edition of the Wiring Regulations). The DPC availability and commenting period is scheduled for June to August 2017 and will be accessible via the BSI Draft Review Portal
When the PEN conductor fails, not only does this present a shock hazard but the diverted neutral current can also create a significant heat build-up, as it typically makes a circuit via exposed metalwork (such as gas, water and oil pipes, etc.) – which can then lead to fire.
Data obtained from the Health and Safety Executive shows at least one incident of an open-circuit PEN conductor is reported every day - with around 10% of them leading to injury. But as many incidents go unreported, it’s believed the real figure could be significantly higher.
“Anecdotal evidence suggests that open-circuit PEN conductors might be a growing problem due to a range of factors – including our ageing distribution system, metallic service pipes being replaced and the theft of copper from cables”, explains Martyn Allen, Technical Director at Electrical Safety First.
“The Charity is committed to promoting collaborative working and, while electrical distributors are legally required to ensure the safety of the electrical distribution network, we believe that the electrical installation sector can also help reduce the risk that open-circuit PEN conductors can present.”
This opportunity to help mitigate the risk has also been recognised and considered by the Committees responsible for developing the 18th Edition of the IET Wiring Regulations. Requirements for foundation earthing, supplementary earth electrodes and over-voltage detection/protection devices may be included in the draft for public comment (DPC) to BS 7671: 2018 (18th edition of the Wiring Regulations). The DPC availability and commenting period is scheduled for June to August 2017 and will be accessible via the BSI Draft Review Portal
