Urban cities are densely populated where critical electrical infrastructure, primarily underground, shares or is located in close proximity to gas, steam and other utilities due to limited space and point of service needs for businesses and residents. On average there are over 5,000 explosive events and many more fires and smoking events in underground vaults, manholes and other structures. The co-location of natural gas distribution lines or buried gas lines in close proximity to electric confined spaces presents a real and present danger when electric equipment and distribution cables degrade or fail.

These failures can release toxic and explosive gases that can reach enough concentration in a confined space to affect worker safety (OHSA) and cause large explosive events. Supplied natural gas from collocated or nearby buried lines can also leak into electric structures and collect in similar concentrations to cause the release of large amounts of energy.

IEEE Guide 2417TM-2022 defines manhole events, summarizes the causes of these events and compiles recommendations to help detect, prevent, and mitigate these events. Active monitoring is one of the recommendations to provide the early detection of flammable gases before they reach explosive concentrations or concentrations hazardous to worker safety.

CNIguard has developed its External Sensor Module (ESM) to detect methane, carbon monoxide, hydrogen, acetylene, ethylene and hydrogen sulfide. The detection of gases has been deployed and tested at four (4) major investor owned utilities and has successfully mitigated potential events dramatically reducing the risk posture of these utilities. The system is typically first deployed in critical and priority areas to provide critical risk reduction to the public, workers and critical infrastructure.

These include:

• Locations with known history of events
• Areas with high pedestrian foot traffic
• Sports arenas
• Government buildings
• Schools, hospitals, libraries
• Ports and transportation infrastructure
• Manholes or vaults with co-located utility ROWs
• Other critical locations