A key challenge for distribution and transmission system operators is to relate the retrofitting of monitoring systems to support asset management aligned with the continuity of service within the electrical network. The research within this study demonstrates how a Smart System Integration approach, utilising a wireless sensor network (WSN), can provide a low cost and scalable sensor platform for in situ sensing of SF6 within substations. In this study, the design and manufacturing stages of an ultra-low power WSN are outlined. The WSN is evaluated within a high-voltage laboratory and deployed within a 400 kV substation. Results indicated that the system can reliably transmit data within a noise environment, recover when there is a mote failure without data loss, can operate on batteries for 1.5 years or 5 years taking 1 SF6 density measurement every 60 or 300 s, respectively. The findings of this research demonstrated the advantageous features of WSNs, namely low cost, rapid deployment, reliable and secure data transfer, adaptive and scalable sensor platform.@en