Danger at the distribution point, with Gavin Parker

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Gavin Parker shares critical lessons from his decades of experience responding to dangerous and disruptive substation fires across the electrical network 

When a fire broke out at an electricity substation in Hayes on 22 March 2025, it triggered a major shutdown at Heathrow Airport. The airport remained closed for 18 hours, disrupting flights for around 200,000 passengers. Although Heathrow has three substations and emergency back-up systems, delays in switching power supplies exposed weaknesses in its operational resilience. 

Electrical substations, like the one involved in the Heathrow incident, are a critical part of the power distribution network. Fires at these sites pose a range of risks—high-voltage equipment, potential explosions, hazardous smoke, and environmental contamination—all of which demand a carefully coordinated and safety-driven emergency response. 

To better understand how fire services prepare for and respond to substation fires, Gavin Parker, an expert in electrical infrastructure and emergency planning, shares insights that detail the unique hazards of these incidents and outline key operational considerations for firefighters and incident commanders. 

Transmission and distribution network 

There are many types of electrical substations that form part of the transmission and distribution network, including transmission, distribution, converter and collector. Transformer yards (switchyards) may be situated within a substation or at a power station. 

Substation fire hazards 

Substation fires present numerous risks. High-voltage equipment can arc and electrocute responders if approached improperly, including through indirect contact with conductive materials, which can be fatal. Transformer failures may lead to explosions, projecting debris and igniting nearby materials.  

Burning electrical insulation and cooling oils can release hazardous fumes, creating toxic smoke hazards. Heat and explosions may also damage steel and concrete supports, leading to structural instability and potential collapse. 

Apart from risks to safety, fires in substations can have severe consequences, disrupting power supply and causing significant financial and environmental damage. Key impacts include: 

Power disruptions: Fires can lead to power outages that disrupt power generation and supply to residential, commercial, and industrial operations, including manufacturing processes. Prolonged outages can halt critical systems, causing disruption, production delays and financial losses. 

Property damage: Intense heat and flames can severely damage infrastructure and electrical equipment. Repair and replacement costs can be substantial, often requiring extended downtime. 

Environmental impact: Transformer fires at substations may release insulating oil and other hazardous substances, contaminating soil and water. Polychlorinated biphenyls (PCBs), historically used in older transformers, pose additional environmental and health risks if released. 

Pre-incident planning 

Fire services should engage in pre-incident planning to enhance preparedness. This includes conducting site visits with utility providers to identify access procedures, specialist on-site or remote isolation procedures, and hazardous zones. Personnel should be trained in electrical safety, the use of Thermal Imaging Cameras (TICs), and specialised suppression tactics.  

Clear response procedures should be established, including a designated staging area for assembly before entry.

Gavin Parker

Fire services should also maintain up-to-date contact information for both business and after-hours emergencies with power companies to enable timely access and de-energisation of affected equipment. 

Utility and distribution companies play a crucial role in substation fire incidents. Firefighters should not enter an electrical substation unless accompanied by a representative from the power authority or distribution company. Entering a high-voltage area and commencing operations before confirmation of power isolation can be fatal. Maintaining direct communication with utility representatives is essential to receive real-time updates during the incident. 

Fire suppression tactics 

Substation fires require a strategic approach and dynamic risk assessment to minimise risks while effectively controlling the fire. 

Monitor burning from a safe distance: Burning electrical equipment will, in most cases, have to be replaced. Contact the power distribution authority and wait for them to arrive. Under no circumstances should firefighters enter a substation before power distribution company personnel arrive. 

Community warnings and isolation of the area: Issue community warnings/information for smoke and traffic restrictions. Liaise with police and local authorities for a traffic management plan. Keep unauthorized persons away. Consider smoke plume modelling if available to assist with planning and community warnings. 

Be alert to the risk of transformer explosions, smoke hazards and oil releases: Stay upwind and consider initial downwind evacuation and warnings.  

Defensive positioning: Firefighters should maintain a safe distance and use non-conductive materials and broken hose streams to de-energised equipment for suppression. 

Co-ordinated suppression plans: The fire service incident controller should liaise with site specialists such as a site Emergency Service Liaison Officer (ESLO or Emergency Service  Officer), Environmental Protection Authority (EPA) representatives and other stakeholders to formulate planning. 

Use of dry chemical agents: Class C extinguishing agents, such as dry powders or CO2, are preferred for energised electrical fires. 

Foam or water application: When transformers contain oil, foam or water may be used after confirmation of de-energisation. 

Cooling exposed equipment: Applying water in a fog (semi-fog) pattern from a safe distance can prevent adjacent equipment from overheating and fire spread. 

Monitor and manage contaminated water and oil runoff: Monitor for off-site release, utilise runoff management procedures such as bunding, containment, or direct it away from water catchments. 

Monitoring fire conditions to ensure extinguishment: Following suppression, the site may have to be monitored to ensure complete extinguishment; traditional overhaul procedures may not be possible, due to the nature of the site and risks. 

Once the fire is controlled, firefighters should monitor for re-ignition, as smouldering insulation or oil residues may reignite.  

Conclusion 

Substation fires demand a highly coordinated, safety-conscious approach. Fire services must emphasise pre-incident planning, specialised training, and collaboration with utility providers to ensure safe and effective incident resolution. 

Gavin Parker

The incident at Heathrow highlights how a single point of failure at a substation can have wide-reaching consequences beyond the immediate fireground. Effective response plans, developed in partnership with utility companies, are essential not only for firefighter safety but also for minimising disruption to critical infrastructure. 

This article was originally published in the May 2025 Edition of International Fire & Safety Journal. To read your FREE copy, click here. 

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