Powering Progress or Fuelling Risk? Lithium-Ion Battery Fire Dangers on UK Construction Sites

Powering Progress or Fuelling Risk? Lithium-Ion Battery Fire Dangers on UK Construction Sites

Lithium-ion batteries are becoming increasingly popular across the UK construction industry. With mounting pressure to make sustainable choices and align with ESG commitments, a growing number of construction sites are switching to lithium-ion battery-powered options.

Despite supporting the shift to sustainable construction, lithium-ion batteries bring new and evolving fire risks that are not always understood or accounted for on site. These risks do not just affect safety; they can disrupt programmes, damage assets and create significant compliance challenges. Understanding and mitigating the risk of lithium-ion battery fires is essential across all construction sites.

Where are lithium-ion batteries used in construction?

Lithium-ion batteries are prominent in the construction industry, with more sites switching to lithium-ion batteries, perhaps without realising. You can find them in:

On live sites, these batteries are often concentrated in higher-risk areas such as tool-storage containers, welfare units and temporary charging stations. Overnight charging, particularly in enclosed or poorly ventilated spaces, is a common practice that can significantly increase fire risk if it is not properly controlled.

Why are lithium-ion battery fires so dangerous?

Lithium-ion battery fires behave differently from traditional electrical fires. They can reach extreme temperatures and spread quickly due to the thermal runaway in the battery. This is an uncontrollable, self-heating state that can only be stopped by the removal of heat or chemicals. Damage to lithium-ion batteries will cause this thermal runaway, which can be broken down into the following steps:

Lithium-ion batteries require a different response to traditional fires. Extinguishing them should be left to professionals unless a fire is blocking the only safe means of escape. Focus instead on accurate fire risk assessments that consider lithium-ion devices, alongside proper maintenance and storage of equipment.

Mitigating the risk of lithium-ion battery fires

Understanding the role everyone must play helps site owners and managers implement the training and procedures needed to keep people safe. Procedures will vary depending on the batteries in use and the size of the construction site, but the following controls are a useful starting point.

Safely handling and storing electrical tools

Correct handling of electrical tools can help to prevent damage to lithium-ion batteries, which can cause a fire. Even the smallest of drops can damage a battery cell, increasing the chance of thermal runaway and the battery igniting.

Electric power tools should be handled correctly, and any drops or knocks should be inspected thoroughly. Damaged tools or batteries should be removed from use, reported and inspected further by site management.

Tools also need to be stored correctly when not in use. Store them overnight in a cool, dry space to reduce the chance of overheating. Site owners should provide suitable spaces for storing and charging lithium-ion-powered devices throughout the working day, ensuring tools are not left charging unattended or overnight. Charging spaces should be separated from active parts of the site to reduce the risk of fire spread.

Recognising short-circuit signs

A short circuit in a lithium-ion battery can cause a fire, so recognising warning signs is essential. Issues can include:

Understanding state of charge

State of charge (SOC) in lithium-ion batteries indicates the remaining energy as a percentage of its total capacity, and you need to understand your battery's SOC to see how much usable energy is left. The SOC is typically measured as a percentage, and you want your SOC to remain stable to prevent overcharging, which can damage the lithium-ion battery.

Best practices for SOC include storing your battery at the right temperature, avoiding extreme heat or cold, regularly calibrating your battery management system, and checking the SOC regularly. The SOC should ideally be between 20% and 80% for daily use to enhance the battery lifespan.

Updating ESG to consider lithium-ion batteries

Lithium-ion battery risks must now be fully considered within existing fire safety and risk management frameworks. Under the Regulatory Reform (Fire Safety) Order 2005, the Responsible Person has a duty to assess and manage fire risks on site, including those associated with lithium-ion batteries.

Fire risk assessments should be updated to account for the number, type, and capacity of batteries on site, charging and storage arrangements, proximity to combustible materials, and emergency response procedures for lithium-ion incidents. With insurers and regulators placing increasing scrutiny on these risks, organisations must ensure appropriate control measures are documented and consistently implemented.

As construction sites continue to adopt more sustainable technologies, including electric construction vehicles, it is important to recognise that new risks can emerge alongside environmental benefits. While electric-powered devices offer advantages such as reduced noise, zero emissions, and fewer trailing cables, lithium-ion batteries present a heightened fire risk, particularly if damaged. A single battery failure can rapidly escalate, potentially affecting entire fleets and causing extensive damage across a construction site.

Providing adequate fire protection for lithium-ion batteries

As lithium-ion batteries are a fire risk, they need to be properly included in your fire risk assessment and fire protection plans. The risk has been formally recognised internationally. The revised BS ISO 3941:2026 introduces Class L, a dedicated fire classification for lithium-ion battery incidents, recognising the difference of these fires from traditional electrical fires.

Consider the number of lithium-ion batteries on site at any one time and ensure appropriate fire equipment is available. As with other fire extinguishers, equipment designed for lithium-ion batteries is intended to provide a safe means of escape if an exit is blocked. Fire blankets for electric vehicles and professional response arrangements should also be considered where appropriate.

When conducting fire safety training for your staff on-site, you will want to include lithium-ion batteries, explain how they behave differently, and ensure everyone understands what to do in the event of a lithium-ion battery fire.