Surge Protection Replacement at Office Building

During the annual Power Factor Correction (PFC) service, an inspection of the on-site Surge Protection Device (SPD) identified reduced protection levels on two of the three phases. This degradation is most likely attributable to a recent voltage transient on the incoming electrical supply, which has partially exhausted the internal protection components of the device. As a result, the SPD was deemed no longer capable of providing the required level of protection and was recommended for replacement to maintain system integrity and compliance.

The existing Surge Protection Device was DIN-rail mounted within the mains Low Voltage (LV) panel and supplied via a 100A moulded case circuit breaker (MCCB), allowing for straightforward and safe replacement. A return visit to site was arranged, during which our engineer installed a direct replacement unit. The new SPD was fitted using the existing mounting arrangement and power cabling, minimising disruption and ensuring continuity of protection.

The installed Type 1/2 Surge Protection Device is designed to provide combined protection against high-energy surge events, such as lightning-induced transients, as well as lower-level over-voltage conditions arising from operational events like load switching. Once installed, the device restored full surge protection across all three phases, safeguarding downstream equipment and improving the overall resilience of the site’s electrical installation.