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.
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Discussions with manufacturers & installers of EV charging, in addition to global case studies, provided these possible scenarios for AC & DC charging.
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Please note, Australian Standards enforce the installation of an isolator switch within 2 meters of an EV charging unit.
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The RCM Tick & Australian Standards are explained in more detail below.
The question is; 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.
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.
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:
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Turn unit off at isolator switch (AS states isolator within 2m of unit*)
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Disconnect power to the EV charging circuit from distribution board
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Unplug charging cable from car^
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Use vehicle app or dashboard to release charging cable from car (cuts charge)
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For DC units, hit red emergency stop button (usually located on front of unit).
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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.
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^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.
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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.
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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.
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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.