04.7 EV extrication considerations
How is patient extrication different with an EV?
As electric vehicles become commonplace, emergency responders will experience collisions & thermal events (battery fires) more commonly.
From a patient extrication perspective, what do we know & what do we need to learn about rescuing someone from an EV, compared with a traditional ICEV
We've been working with the Victorian State Emergency Service & other Australian rescue agencies to start building a set of draft considerations for rescue responders when dealing with an EV.
Please note these considerations are information only & should not be taken as recommendations for EV extrication. Agency SOPs should always be followed.
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Watch: How to isolate EV HV battery
How to find Emergency Response Guides for EVs
Considerations for EV extrication
Thermal runaway - dynamic risk assessment
AT ALL TIMES rescue responders should monitor an electric vehicle (EV) for signs of thermal runaway, which can lead to fire or, very rarely, vapour cloud explosion. More info at 'EV traction battery fire behaviour'
Both pose a serious risk to responder safety!
EV identification
Assume you're dealing with an electric vehicle (EV) unless proven otherwise. Find relevant emergency response guide (ERG) via ANCAP Rescue, Euro Rescue, Crash Recovery System or online. Use 'EV' tape to immediately identify to all attending responders.
Ask driver &/or passengers
Look for blue EV badge on front & rear numberplate (Australia only)
External badging around vehicle saying 'electric', 'low emission', 'PHEV', 'EV'
Approach
As responders approach an EV:
Consider approaching from a 30% angle to avoid responder injury from suddenly moving vehicle
There may be no engine noise & EVs may move silently & rapidly
Exposures
Responders should look for:
Exposed ORANGE HV cables & scattered battery cells. EVs run at >400V & both present a potential electrocution risk
Dark patches on battery pack (underside) that may indicate rapid heat build up (monitor with TIC)
Obvious damage to the battery pack & fluids on ground; small amounts of electrolyte will be clear, coolant is blue/green tinted
Immobilisation
EVs can move silently & with instant speed. Ensure you have the correct ERG for the EV make & model. Rescuers should consider:
Listen for engine, switch off. Apply park brake. Chock wheels; truck sized chocks may be needed to adequately hold EV in place
If possible, ask driver to place EV in park, push on/off button & remove proximity keys
Some EVs, primarily Teslas, use the drivers smartphone as a key, but may also use a 'card' key', a finger ring or even a bracelet. They may not have an On/Off button.
Isolate high voltage systems
To make the EV safer to work around, rescuers can isolate low voltage (LV) & high voltage (HV) systems. Review the ERG for location & isolation information.
LV: 12V accessory battery typically located under bonnet or under floor of boot.
Ensure doors / windows / bonnet / boot are open if required (difficult to open once 12V is disconnected)
HV: >60V traction battery that gives EV momentum. Located beneath floor pan in passenger EVs.
May be a marked responder cut loop or a pull fuse. Use 18 inch insulated bolt cutters.
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HV systems should automatically isolate upon impact involving safety systems (airbags, seatbelt pretensioners)
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When LV (12V) system is disconnected, contactors to HV system should remain in ‘open’ position, thereby isolating HV
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Where available, also conduct manual isolation of HV systems for additional safety while extrication is taking place
Rescue responder protection
To enhance rescue responder protection:
Monitor HV battery pack (under floor pan of EV) with TIC to detect heat increase
Lay & charge hose lines for battery cooling &/or fire suppression
Ensure BA / SCBA operators are standing by
Stabilisation
An EV HV battery is heavy - accounting for approximately 30% of overall weight - & EVs may be more likely to stay on wheels. For example, a Tesla Model 3 has an average kerb weight 1800kgs & a HV battery average weight of 550kgs.
If relocation required, roll EV away from structures to enable access, check ERG for hoisting points on EV that provide 4 point stabilisation. 5th point stabilisation will depend on type of incident.
EV on wheels:
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Consider where block & wedge stabilisation will go
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Add EV tape to battery pack for visible reminder (if possible)
EV on side:
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Use side stabilisation with multiple wedges
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Underside stabilise forward of front tyres & rear of rear tyres
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Consider construction – soft materials like aluminium & kevlar may rip if used as an anchor (eg. Tesla bonnet is light aluminium)
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Add EV tape to battery pack for visible reminder
EV on roof:
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Similar to all ICE vehicles
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Consider access to HV cut loop or pull fuse for HV disconnection
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Add EV tape to battery pack for visible reminder (if possible)
Note: Do not touch, push off or penetrate the HV battery pack area, which sits along the floor pan between chassis rails on all passenger EVs. Stick outside of battery zone – front & rear of tyres.
Glass management
Glass may form part of the structural integrity of EV & responders should review ERG for glass type that may need to be removed/managed to reach HV disconnects.
Cutting laminated glass leads to glass dust and needs to be managed accordingly
Casualty protection (soft/hard) & sharps protection
Use beluga tool for laminated glass & windscreen splinter guard
Gaining access & extrication
Rescuers should consider a further review of the ERG & that traditional entry &/or cut points may vary in EVs. Always expose & investigate before commencing tool operations.
Important: Ramming off vehicle floor may cause battery abuse leading to thermal runaway, which carries the risk of fire & vapour cloud explosion. Always consider placement of ram supports in accordance with the vehicle's ERG.
Using existing techniques - open doors / ask driver to open locked doors & use manual override latch (see ERG)
AC/DC converter may be located in footwell & should be checked in the ERG.
Passenger EV HV battery is located between chassis rails, along floor pan
Airbags, seats & vehicle controls are managed similarly to traditionally fuelled vehicles
Extrication via doors - use rattle / spread / cut method:
From front:
Manipulate front guard to expose hinges & check for HV cables
From rear:
Consider working tool along door edge to access Nader bolt to minimise skinning doors, checking vehicle construction & for HV cables
Consider potential for gull wing doors - currently only in Tesla Model X
Consider power assisted doors, such as tailgate
Side extrication:
Remove both doors then B pillar, referring to ERG for location of HV cables
Rear extrication:
If possible, wind windows down to minimise cutting side laminated glass windows.
Conduct a dynamic risk assessment regarding a glass roof - should you remove / leave?
Ramming:
B to A dash roll:
Consider relief cut location with vehicle HV systems.
Internal - floor, dash / doors:
Refer to ERG for locations of HV systems
If using cross rams, consider penetration of ram into HV battery & location of HV cables
Dash lift - refer to ERG & consider:
Location of HV cables
Vehicle construction
Pushing off HV systems (expose first) & pushing off floor pan (risk of abusing battery cells)
Conclude rescue & handover
Consider potential contamination of PPC / PPE & follow agency clean up procedures. Incident controller should make towing / recovery aware vehicle is electric & provide make, model & ERG for towing instructions if required.
Use 'EV' tape for immediate identification by all responders, towing & storage
Brief investigators on modifications made, such as cut seat belts, HV isolation, cut loop etc
Example only: refer to your agency for guidance
Body recovery
Rescuers should keep all previous considerations in mind. Firefighters should remain on on scene until EV has been handed over to towing
Firefighters should remain on scene to provide charged line & BA/SCBA operators for immediate suppression & cooling of battery pack
Responders should brief controlling agency for investigation on inherent EV risks
Post incident
Use EV tape or similar for immediate identification for all organisations processing vehicle. Ensure towing / vehicle recovery are aware vehicle is electric.
Storage / tow yards should consider keeping damaged EVs separated from other vehicles due to risk of secondary ignition
04.8 Risk of electrocution (coming)