POWER SUPPLY
SURGE PROTECTION
SURGE PROTECTION IS REQUIRED TO BE INSTALLED UNDER IRELAND’S NATIONAL RULES FOR ELECTRICAL INSTALLATIONS I.S 10101:2020. KIRSTY JOHNSON MIET, TECHNICAL DIRECTOR AT SURGE PROTECTION DEVICES LTD, EXPLAINS WHEN AND WHY WE NEED IT… Surge protection made simple
A surge protection device (SPD) is designed to divert excess voltage to earth, away from sensitive electrical equipment. Unlike miniature circuit breakers (MCBs) and residual current breakers with over-current (RCBOs), SPDs are designed not to cut the power supply, but to protect electrical equipment instead, without disrupting the installation. Why is surge protection required in installations now? With the ever-increasing amount of sensitive technology used in electrical installations, from domestic properties to larger commercial industrial properties, overvoltage protection is more necessary than ever. The equipment used nowadays contains components with extremely low withstand capabilities, unlike the larger components used in older technology. Surge protection helps preserve this sensitive equipment. I have seen a few types of surge arresters; how do I know which one I need? Most installations will require type 2
devices to conform to I.S. 10101. However, if the installation is fed via an overhead supply or features an external lightning protections system, the SPD should be a type 1 device, which is designed to protect against direct lightning strikes. What else do I need to consider before selecting a surge device? The earthing system at the property. If the property has a TT earth, the SPD must be designed specifically for use on TT systems, due to the internal configuration of the SPD. What do the regulations say? Regulation 443.4 protection against transient overvoltages shall be installed where the consequences caused by overvoltage effects affect human life, safety services, medical care facilities, public services and cultural heritage, commercial or industrial activity, or a large number of individuals. For all other cases, a risk assessment according to 443.5 shall be performed to determine if protection against transient overvoltage is required. Otherwise, the
electrical installation shall be provided with protection against transient overvoltage. In most circumstances, even if the risk assessment is performed, the installation will still contain equipment that would benefit from the application of surge protection. The risk assessment quantifies the risk of damage due to lightning effects, not due to switching within an installation or from the network. For domestic installations, an SPD should be installed unless the value of the installation is less than five times the value of the SPD, which is unlikely in most situations. For more information and CPD training about surge protection, please visit the training section on our website or call our office.
T: +44 (0)1484 851747 E: info@surgedevices.co.uk www.surgedevices.co.uk
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