Following the failure of the roof plant room tapoff connection on one of two distribution busbars we were asked to carry out infrared, ultrasonic, visual inspections and insulation & continuity tests of both busbars. A short circuit to earth and/or between phase conductors within the busbar joint resulted in an H.V. outage and a serious fire affecting the rooftop plant room. When we arrived on site the damaged busbar was still isolated and all load was supported by the second busbar leaving the hospital vulnerable to an outage.

PROCESS
Thermal and digital images were recorded of all busbar joints throughout the run of the energised busbar which was carrying the entire building load. Ultrasonic analysis was also carried out on each joint. The tapoffs supplying the distribution equipment were opened and further thermography and ultrasound analysis was carried out. The damaged busbar was visually inspected and all tapoffs were opened and tested. the riser cupboards. Insulation and continuity test were also conducted on the damaged busbar.

REPORT
We were able to confirm that although the damaged busbar had failed catastrophically it had not affected the rest of the busbar. We produced a full report which included thermal and digital images along with ultrasonic examples and test results from the continuity and insulation tests. In addition we included a list of recommendations to be carried out to both busbars that would help to ensure the longevity, reliability and safety of the system.

REMEDIAL WORKS
Following our report we were asked to carry out the majority of our recommendations that the on-site staff were not able to complete. A series of small shutdowns were arranged to allow us to install additional support brackets, re-terminate incoming and outgoing busbar and tapoff connections and complete further insulation and continuity tests. We identified the fault as a damaged component that should not have been part of the original installation. This was replaced before our second visit and was re-tested while we were on site.

CONCLUSION
Although we were called to site after the failure, during our visits we were able to identify and subsequently rectify a number of potentially serious defects in what is a relatively new installation. Thankfully we did not identify any thermal or ultrasonic issues with the second busbar. With long term agreements in place with hospital trusts it is imperative that systems are installed as designed to ensure maximum maintenance efficiency and reliability for the life of a building.