EV Charging in Car Parks: Fire Safety, Ventilation and Installation Requirements
Installing EV chargers in open-air surface car parks is relatively straightforward. Installing them in enclosed, underground or multi-storey car parks is a different proposition entirely. The combination of high-power electrical equipment, vehicles, enclosed spaces and ventilation limitations creates a set of safety requirements that go well beyond simply mounting chargers on walls.
Building owners and operators across Manchester are facing this challenge as demand for EV charging grows in commercial car parks, residential basement parking, multi-storey structures attached to offices and retail, and covered parking at apartment buildings. The installations are technically achievable, but they require careful design that addresses fire safety, ventilation, electrical infrastructure and ongoing maintenance in ways that surface installations do not.
This guide covers the specific requirements for EV charging in enclosed car park environments, based on current regulations, industry guidance and our experience installing and inspecting these systems across Greater Manchester.
Why Enclosed Car Parks Present Different Challenges
An EV charging in an enclosed car park operates in conditions that amplify several risk factors.
Heat Dissipation
Chargers generate heat during operation. In an open environment, this heat dissipates naturally. In an enclosed space — particularly an underground car park with limited air movement — heat accumulates. Multiple chargers operating simultaneously in an enclosed area raise ambient temperatures, which affects the performance and lifespan of the chargers themselves, the cables feeding them, and the vehicles being charged.
Cable current-carrying capacity is directly affected by ambient temperature. A cable rated for 32 amps at 30 degrees Celsius may only be safe at 25 amps at 40 degrees. If the cable sizing does not account for the elevated temperatures in an enclosed car park, the installation is potentially unsafe.
Ventilation Requirements
Enclosed car parks already require mechanical ventilation to manage exhaust fumes from internal combustion engine vehicles. The introduction of EV charging adds a new ventilation consideration: thermal management during normal charging, and gas dispersal in the event of a battery thermal runaway incident.
While battery fires in EVs are statistically rare, the consequences in an enclosed space are severe. A thermal runaway event produces toxic gases including hydrogen fluoride, which are heavier than air and accumulate in low-lying enclosed spaces. Ventilation systems in car parks with EV charging must be designed to handle these scenarios.
Fire Detection and Suppression
Standard car park fire detection systems are designed around the fire characteristics of conventional vehicles — liquid fuel fires that burn with visible flame and significant smoke. Battery fires behave differently: they can re-ignite after apparent extinguishment, they produce different gas signatures, and they may not trigger conventional smoke detectors as quickly.
Car parks installing EV charging need fire detection systems that can identify the specific characteristics of a battery event, and suppression strategies that account for the different behaviour of lithium-ion battery fires.
Regulatory and Guidance Framework
There is no single regulation that covers all aspects of EV charging in enclosed car parks. The requirements come from several overlapping sources.
Building Regulations Approved Document S
Approved Document S sets out requirements for EV charging infrastructure in new buildings. For car parks, it requires the installation of charging points or at minimum cable routes to parking spaces, with specific provisions for ventilation in enclosed areas where charging takes place.
BS 7671 (IET Wiring Regulations)
The electrical installation must comply with BS 7671, which sets requirements for circuit design, cable selection, protective devices, earthing and environmental factors. Section 722 specifically covers EV charging installations, including requirements for RCD protection, cable management and isolation.
Fire Safety Order 2005
The Regulatory Reform (Fire Safety) Order 2005 requires the responsible person for a building to carry out a fire risk assessment and implement appropriate fire safety measures. Adding EV charging to an enclosed car park is a material change that requires the fire risk assessment to be reviewed and updated. The risk assessment must address the specific fire risks associated with EV charging and battery vehicles.
Industry Guidance
The Institution of Engineering and Technology and the Association for Specialist Fire Protection have published guidance on EV charging in enclosed car parks. The guidance covers ventilation rates, fire detection strategies, suppression options and spatial planning. While not legally binding in the same way as regulations, this guidance represents industry best practice and is referenced by fire authorities and insurers.
Ventilation Design for EV Charging Areas
Normal Operation Ventilation
During normal charging operations, ventilation must manage the heat generated by chargers and vehicles. For car parks with mechanical ventilation, the existing system may be adequate if it provides sufficient air changes per hour to prevent excessive temperature build-up.
The critical check is whether the ventilation system was designed with the additional thermal load of EV charging in mind. Most existing car park ventilation systems were designed for exhaust fume extraction, not heat management from multiple high-power electrical loads. An engineering assessment is needed to confirm capacity.
For naturally ventilated car parks — those relying on openings rather than fans — the suitability depends on the size and location of openings relative to the charging areas. Natural ventilation is generally acceptable for car parks with large permanent openings (at least 25 percent of the perimeter at each level), but may be insufficient for fully enclosed basement parking.
Emergency Ventilation
In the event of a battery thermal runaway, the ventilation system needs to operate in emergency mode to extract toxic gases and smoke. This typically requires higher air change rates than normal operation, smoke and gas detection linked to the ventilation controls, override capability to switch from normal to emergency mode, power supply resilience (the ventilation must continue to operate if the main supply fails), and integration with the building's fire alarm system.
The design of emergency ventilation for EV charging areas should be carried out by a specialist ventilation engineer in conjunction with the fire risk assessor. Generic car park ventilation designs may not adequately address the specific requirements of battery-related incidents.
Fire Detection Requirements
Detection Types
Standard point-type smoke detectors used in many car parks may not provide the fastest response to a battery thermal event. Battery failures often begin with off-gassing before visible smoke develops, and the initial gases may not trigger conventional optical or ionisation smoke detectors effectively.
Enhanced detection options for EV charging areas include linear heat detection cables routed above charging bays that detect temperature rises along their length, gas detection sensors calibrated to identify the volatile organic compounds released during battery failure, thermal imaging cameras that provide continuous temperature monitoring of the charging area, and flame detectors that respond to the infrared signature of a fire rather than relying on smoke reaching a ceiling-mounted detector.
The appropriate detection strategy depends on the car park geometry, ceiling height, ventilation patterns and the number and type of chargers installed. A fire engineer should specify the detection system as part of the overall fire safety design.
Integration with Building Systems
Fire detection in the EV charging area must integrate with the building's fire alarm system. When a detection event occurs, the system should alert building occupants via the fire alarm, switch ventilation to emergency mode, notify the fire service via an automatic alarm connection if appropriate, activate any suppression systems, and isolate power to the affected chargers.
This integration requires careful coordination between the fire alarm installer, the ventilation contractor and the EV charging installer. All three systems need to work together, and the integration must be tested and verified during commissioning.
Fire Suppression Strategies
Sprinkler Systems
Conventional sprinkler systems provide effective first-response fire suppression in car parks. For EV charging areas, the sprinkler design should account for the specific fire load of EVs and the characteristics of battery fires. This may mean higher density sprinkler coverage in charging bays compared to standard parking areas.
Sprinklers will not extinguish a battery thermal runaway — the internal chemical reaction continues regardless of external water application. However, sprinklers perform two critical functions: they cool the burning vehicle and surrounding area, preventing fire spread to adjacent vehicles, and they suppress the fire enough to allow fire service access and intervention.
Water Mist Systems
Water mist systems use fine droplets to cool and suppress fires with significantly less water than conventional sprinklers. They are increasingly specified for enclosed car parks because they reduce water damage, provide effective cooling of large fire loads, and can be designed for high-ceiling environments common in car park structures.
Containment Strategies
Some car park operators are implementing containment strategies alongside suppression. Fire blankets designed for vehicle fires can be deployed over a burning vehicle to contain the fire and limit toxic gas release while awaiting fire service response. Purpose-designed vehicle fire containment systems exist that can be installed at specific charging bays.
Electrical Installation Requirements
Cable Management
Cable routing in car parks must account for vehicle movements, impact risks and the environmental conditions. Cables should be routed at height where possible, using steel trunking or conduit that provides mechanical protection. Surface-mounted cables at low level are vulnerable to vehicle impact and should be avoided.
In multi-storey car parks, vertical cable risers need fire stopping at each floor level to prevent fire spread between levels via the cable routes. This is a Building Regulations requirement that applies to all vertical cable penetrations, not just EV charging cables.
Electrical Distribution
Multiple chargers in a car park need a dedicated distribution board sized for the total connected load with appropriate diversity applied. This distribution board should be located in a position accessible for maintenance but protected from vehicle impact — typically a dedicated electrical cupboard or mounted at height on a structural wall.
Each charger circuit needs individual overcurrent and RCD protection, with discrimination designed so that a fault on one charger trips only that circuit, not the entire car park's charging supply.
Emergency Isolation
There must be a clearly marked emergency isolation switch that disconnects power to all EV chargers simultaneously. This switch must be accessible to car park staff and the fire service, typically located at the car park entrance or in the fire service access lobby.
Individual charger isolation should also be possible without disconnecting the entire system, allowing maintenance on one unit while others continue to operate.
Spatial Planning and Bay Design
Charging Bay Locations
The positioning of EV charging bays within an enclosed car park requires balancing accessibility, safety and infrastructure efficiency. Charging bays should ideally be located near the car park perimeter or near ventilation openings, close to the electrical supply route to minimise cable runs, away from fire escape routes, positioned so that a vehicle fire at a charging bay does not block access to exits, and accessible for fire service intervention.
Concentrating all charging bays in one area of the car park simplifies the electrical and ventilation design but creates a single point of risk. Distributing bays across the car park spreads the risk but increases infrastructure costs.
Clearances and Access
Adequate clearance must be maintained around charging equipment for maintenance access, ventilation and fire service access. Chargers mounted on walls or pillars should not obstruct pedestrian walkways or vehicle manoeuvring space.
Cable management systems should not reduce headroom below the car park's design clearance. In multi-storey car parks with restricted headroom, surface-mounted cable routes need careful planning to avoid creating obstructions.
Ongoing Compliance and Maintenance
Fire Risk Assessment Reviews
The fire risk assessment must be reviewed whenever EV charging equipment is added, modified or significantly altered. The review should be carried out by a competent fire risk assessor who understands the specific risks associated with EV charging in enclosed spaces.
Annual fire risk assessment reviews are recommended for car parks with EV charging, even where the charging equipment has not changed, to ensure that the assessment remains current with evolving guidance and any changes to car park usage or occupancy patterns.
EICR Inspections
The EV charging installation is part of the building's fixed electrical installation and must be included in EICR inspections. For commercial car parks, this means inspection every five years as a minimum. The condition of cables, connections and protective devices in the demanding car park environment should be closely monitored.
Charger Maintenance
A maintenance programme for car park chargers should include regular visual inspection for damage, water ingress and overheating, functional testing of all chargers, verification of RCD and emergency isolation operation, cleaning of connectors and charging cables, firmware updates for networked chargers, and testing of the emergency shutdown system integration.
Manchester-Specific Considerations
Many of Manchester's commercial buildings, particularly in the city centre and inner suburbs, have basement or underground car parks that were built decades before EV charging was contemplated. Retrofitting charging into these spaces often requires creative solutions for cable routing, ventilation modification and fire system integration.
The Arndale Centre, Spinningfields, MediaCityUK, and numerous residential developments across Salford Quays, Ancoats and the Northern Quarter all face similar challenges as their car parks transition to accommodate electric vehicles.
Listed buildings and buildings in conservation areas may face additional planning constraints on external modifications needed for electrical supply upgrades to serve car park charging.
For building owners and operators across Greater Manchester who need to add EV charging to enclosed car parks, professional design that integrates electrical installation, fire safety and ventilation is not optional — it is the only way to achieve a safe, compliant and practical installation.
Professional Assessment and Installation
We design and install EV charging systems for enclosed car parks across Greater Manchester, working with fire engineers and ventilation specialists to deliver installations that meet all regulatory requirements. From initial feasibility assessment through to commissioning and ongoing maintenance, we manage the entire process.
Call us on 0161 312 2240 or email hello@manchestercompliance.co.uk to discuss your car park EV charging project. We cover all areas of Greater Manchester including Manchester city centre, Salford, Stockport, Oldham, Tameside and Rochdale.