Are electric vehicles a greater fire risk?

Incidents involving motor vehicles catching fire and the subsequent consequences are well documented and in recent times regretfully have become a common sight on UK roads.

Causes can include overheating components, wearing components and electrical faults providing a source of ignition in an atmosphere or area already suffering from an ingress of fuel, lubricants or combustible materials.

The risk of an electric vehicle (EV) catching fire has been cited as potentially greater than those occurring in ICE (Internal Combustion engine) equipped vehicles.^*

This potentially increased risk is associated with the electrical components on the vehicle, some of them are operating at high voltages and a new phenomenon whereby EV’s are catching fire, without warning, despite vehicles being switched off and electrically isolated.

Our previous insight paper raised awareness of the potential risks associated with thermal runaway, whereby in an EV, vehicle propulsion batteries fail internally, causing short-circuiting within the battery cells in a flammable environment and as combustion occurs within the battery, new flammable products including oxygen are produced, thus further fuelling the fire.

Physical damage to battery packs, unknown to the driver but causing internal issues to the battery pack itself, can result in combustion later on, possibly sometime after vehicle has been parked.

This presents challenges to our emergency services as although the ensuing fires can be controlled utilising normal procedures, there is the possibility of the battery itself re-igniting after a short period. To manage this, the emergency services utilise thermal imaging equipment to monitor hot spots on the vehicle involved, however this requires them to remain present at the scene for longer periods to ensure the battery packs are cooled using water rather than other extinguishants normally associated with fighting a vehicle fire.

Some parking areas may contain fire extinguishing systems that are not be suitable to control the type of fire seen with an EV where cooling the battery pack is key to control thermal runaway.

A well-known car manufacturer has recently experienced four instances of a fire in a particular model, believed to be caused by faults in the vehicle batteries. This has initiated a mass recall of vehicles.

Where’s the risk?

The most significant areas of concern are where vehicles are parked, stored, transported or undergoing recharging in confined environments such as:

• Car parks, both multi storey and particularly underground;
• Bus garages where vehicles are parked within the garage building. Charging facilities will require vehicles to be parked closely together;
• Open air storage and display facilities where there are large accumulations of vehicles of all types used in conjunction with the motor trade;
• EV vehicle maintainers and repairers - where work is being undertaken on vehicles and damage or faults with to the vehicle battery packs may be unknown, particularly where vehicles despite being isolated, may be left overnight inside;
• EV test facilities - again where vehicles may be parked overnight inside buildings;
• EV recharging stations both inside and outside.
• The transportation of EV’s both singly and in multiples i.e. vehicle transporters and recovery providers

How can this risk be managed?

• Some locations place controls on where particular types of vehicles can be parked. Examples include the parking of Compressed Natural Gas powered vehicles into separate areas but the segregation of EV’s in parking areas, unless recharging, is currently, rare.
• Parking segregation is another approach, but to a degree in recent times this has been compromised by the necessity to utilise all space. However, segregation is considered in many cases with the siting of EV charge points away from other vehicles and with larger spaces.
• The types of fire suppression systems installed in parking areas – High pressure water mist installations are thought to be (together with providing a cooling effect), better suited to displace the oxygen environment reducing the risk of fire spreading and re- ignition.
• By the use and availability of vehicle fire blanket systems which if able to be deployed safely or used as a preventative measure when vehicles are left, can be effective and control the spread of combustion to other areas and vehicles. Such products are now available for car sized vehicles and could form part of the fixed firefighting systems made available in premises.
• The materials used in fire blankets are being built proactively into battery propulsion systems to assist in preventing spread should a battery pack fail

In many cases the length of charging cable provided by the vehicle manufactures and the siting of EV charge points particularly as we see more and more domestic installations can compromise the ideal situation of placing an electric vehicle away from other vehicles and premises.

Technical developments are moving fast – we have had several decades to manage the risks presented by vehicles with ICE and manufacturers will seek to continue to mitigate this risk in the design of their product, but ultimately, they cannot control the way a vehicle is used or maintained.

The specialist practises of Transport Risk Management and Property Risk Engineering continue to monitor, advise and raise awareness of emerging risks with insight and detailed surveys.

Please contact us to discuss the services we can provide.

Footnote

^*https://www.technologyreview.com/2013/11/26/175306/are-electric-vehicles-a-fire-hazard/

Author

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Andrew Millinship

Practice Leader – Transport Risk

email Email phone +44 0 7764 836 394

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