04.6 Risks - EV fire while charging

Our project focus - risks to emergency responders at an EV fire + energised charging

Our research discovered that just over a third of reported electric vehicle traction battery fires occured while connected to energised AC or DC charging, or within one hour of being disconnected from energised charging.

Discussions with manufacturers & installers of EV charging, in addition to global case studies, provided these possible scenarios for AC & DC charging.

Please note, Australian Standards enforce the installation of an isolator switch within 2 meters of an EV charging unit.

The RCM Tick & Australian Standards are explained in more detail below.

The question; could an EV traction battery fire at a charging unit result in two fire risks - a traction battery fire & an energised electrical fire?

EV connected to RCM & AS compliant AC charging

If a fault is detected, the RCD & circuit breaker will cut power between the switchboard & charging unit. 
Theoretically safe to suppress flames at EV & charging unit with water.

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EV connected to RCM & AS compliant DC charging

DC units contain sensitive monitoring system to detect earth leakage, overcurrent & short circuit. Traction battery fire will cause detection of short circuit &/or overcurrent, & cut power supply between unit & EV. 
AC power may still be live within the DC unit & should be considered so until disconnected at distribution board.
Theoretically safe to suppress flames at EV.

EV connected to non-compliant AC charging

Risk of potential electrocution from continued power supply if RCD & circuit breaker NOT appropriately rated &/or installed.
Unsafe to suppress flames until disconnected at distribution board.

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EV connected to non-compliant
DC charging

Due to the large power supply required for DC charging, unit installations are electrically engineered & signed off by local power authority. Risk of emergency responders encountering non-compliant DC units very low.

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Best practice with EV fire connected to charging

Depending on how advanced the incident has progressed, one or more of these steps can be taken:

  1. Turn unit off at isolator switch (AS states isolator within 2m of unit*)

  2. Disconnect power to the EV charging circuit from distribution board

  3. Unplug charging cable from car^

  4. Use vehicle app or dashboard to release charging cable from car (cuts charge)

  5. For DC units, hit red emergency stop button (usually located on front of unit).

The Institute for Safety (IFV) in The Netherlands have released information showing when it is safe to cut the charging cable on Level 1 portable EVSE cables & Level 2 AC wall chargers. This is available on our Links & Resources page.

^Depending on EV model, it may not release a charging cable when powered off. 

More about RCM & Australian Standards for EV charging

AC & DC electric vehicle charging units have a number of safety systems that should prevent an electrical risk to emergency responders should a nearby charging EV traction battery go into thermal runaway.

However, this assumes the charging unit has been manufactured or imported to meet compliance rules set out by the Australian Electrical Equipment Safety System (EESS) & have passed testing that allows it to display the RCM Tick.

It also assumes that the charging unit has been installed to *Australian Standard 'Electrical Installations Wiring Rules' AS/NZS 3000:2018, Appendix P.

 

This standard enforces protective devices for automatic disconnection of power supply in the event of a fault, such as a Residual Current Device (RCM) & circuit breaker. Additionally, an isolator switch should be placed within 2m of the unit.

However, as EV ownership increases in Australia, it's important to note that we are already aware of non-compliant charging equipment being purchased via onsite sales sites & shipped for use & installation.