Protection against high voltage shock
I.
Objective/Purpose:
The purpose is to reduce death and injury due to electric shock during normal operation and in a
crash.
II.
Risk areas and Safety Needs:
A failure of a high voltage system in a vehicle during operation or in a crash may pose risk of
electric shock to people in and around the vehicle and to first responders in the event of a crash.
When the body contacts an energized voltage source and return, current will flow through the
body. The resulting current through the body may induce physiological effects ranging
anywhere from slight pricking sensation to involuntary muscular reactions to cardiac arrest,
breathing arrest, and burns. The effects and probability of ventricular fibrillation depends on
various factors, including the type of current (AC or DC), frequency, magnitude, and duration of
current flow through the body. A vehicle with high voltage propulsion system must be designed
to minimize the risk of electric shock during normal operation and in the event of a crash.
III.
Performance Criteria
The agency was a signatory to GTR No. 13, “Hydrogen and fuel cell vehicles,” in June 2013 and
is proposing the electrical safety requirements specified in GTR No. 13.
In-Use Requirements:

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Protection against direct contact: All high voltage sources in the electric power train or
those galvanically connected to the powertrain that are energized during normal operation
of the vehicle must be protected against direct contact Protection against direct contact
inside the passenger compartment is checked using a standardized test wire, IPXXD and
outside the passenger compartment using a standardized test finger, IPXXB.
Protection against indirect contact: Exposed conductive parts that can be energized in the
event of electrical isolation failure have to be protected against indirect contact.
Conductive barriers or enclosures have to be galvanically connected securely to the
electrical chassis with bonding resistance less than 0.1 ohm.
Electrical isolation: High voltage sources must be appropriately electrically isolated from
the chassis (AC and DC sources with 500 ohms/volt and DC sources with 100 ohms/volt
along with electrical isolation monitoring system). The isolation resistance requirements
of 100 ohms/Volt for DC or 500 ohms/Volt for AC allow maximum body currents of 10
mA DC current and 2 mA AC current, respectively (these levels of current passing
through the body for any duration of time are considered safe).
o When the AC and DC bus are connected, the AC and DC high voltage sources
may have electrical isolation of at least 500 ohm/volt, or the AC and DC high

voltage sources have at least 100 ohm/volt with the AC high voltage sources also
having direct and indirect contact protection.
Functional safety: When the vehicle high voltage battery alone is operational for
providing vehicle’s propulsion power (not the vehicle’s IC engine), at least a momentary
indication is provided to the driver that the vehicle is in “active drive mode.” When
leaving the vehicle, the driver shall be informed by a signal (e.g. optical or audible signal)
if the vehicle is still in the active driving possible mode. If the on-board REESS can be
externally charged, vehicle movement by its own propulsion system shall be impossible
as long as the connector of the external electric power supply is physically connected to
the vehicle inlet.
Post-Crash Requirements:
After the impact of the vehicle, high voltage sources of the electric power train or those which
are galvanically connected to the electric power train must meet one of the measures listed below
to demonstrate that the high voltage systems are not dangerous to the passengers of the vehicle or
to first responders outside the vehicle.
 Absence of high Voltage: After the impact the voltage of components in the powertrain
or those galvanically connected to it is equal or less than 30 VAC or 60 VDC. These
levels of voltage are considered to have no adverse effect on the human body when
contacted.
 Isolation Resistance: After the impact high voltage sources are appropriately electrically
isolated from the chassis (AC and DC sources with 500 ohms/volt, or AC source with
500 ohms/volt and DC sources with 100 ohms/volt along with electrical isolation
monitoring system). The isolation resistance requirements of 100 ohms/Volt for DC or
500 ohms/Volt for AC allow maximum body currents of 10 mA DC current and 2 mA
AC current, respectively (these levels of current passing through the body for any
duration of time are considered safe).
o When the AC and DC bus remain connected after the impact test, the AC and DC
high voltage sources can have electrical isolation of at least 500 ohm/volt or the
AC and DC high voltage sources have electrical isolation of at least 100 ohm/volt
with the AC high voltage sources also meeting the physical protection
requirements or have voltage less than or equal to 30 V.
 Physical protection: It should not be possible to touch live parts after the crash, tested
with the standardized Test Finger (IPXXB). Furthermore protection against indirect
contact has also been fulfilled (resistance between all exposed conductive parts and the
electrical chassis is less than 0.1 ohm).
IV.
US comments
The agency is not proposing the energy option that is in the OICA proposal.
The effect of different levels of body current on the body is presented in Table 13 of IEC 604791 and is presented below.
Table 13 of IEC 60479-1: Time/current zones for d.c. for hand to feet pathway
Zones
Boundaries
DC-1
Up to 2 mA
curve a
Slight pricking sensation possible when making, breaking or rapidly altering
current flow
DC-2
2 mA up to
curve b
Involuntary muscular contractions likely especially when making, breaking or
rapidly altering current flow but usually no harmful electrical physiological
Effects
DC-3
Curve b and
above
Strong involuntary muscular reactions and reversible disturbances of
formation and conduction of impulses in the heart may occur, increasing with
current magnitude and time. Usually no organic damage to be expected
DC-4
1)
Above curve c 1
c 1 -c 2
Physiological effects
Patho-physiological effects may occur such as cardiac arrest, breathing
arrest, and burns or other cellular damage. Probability of ventricular
fibrillation increasing with current magnitude and time
c 2 -c 3
DC-4.1 Probability of ventricular fibrillation increasing up to about 5 %
Beyond curve c 3
DC-4.2 Probability of ventricular fibrillation up to about 50 %
DC-4.3 Probability of ventricular fibrillation above 50 %
1)
For durations of current flow below 200 ms, ventricular fibrillation is only initiated within the vulnerable period if
the relevant thresholds are surpassed. As regards ventricular fibrillation this figure relates to the effects of current
which flows in the path left hand to feet and for upward current. For other current paths the heart current factor has
to be considered.
The DC high voltage source electrical isolation requirement of at least 100 ohm/volt correspond
to DC current through the body of less than 10 mA which is approximately in the middle of the
DC-2 zone as shown in Figure 22 of IEC 60479-1 (shown below). This applies to shock
durations 10 msec and longer.
Figure 22 of IEC 60479-1: Conventional time/current zones of effects of d.c. currents on
persons for a longitudinal upward current path
For single impulse DC current of duration less than 10 msec, IEC 60479-2 has provisions on the
risk of ventricular fibrillation as shown in Figure 20 of IEC 60479-2 (shown below). This figure
is in the zone DC-3 and DC-4 for shock durations less than 10 msec. The line C1 is at the border
of no risk of ventricular fibrillation and 5 percent risk.
The curves indicate the probability of fibrillation risk for current flowing through the
body from the left hand to both feet. For other current paths, see 5.9 in IEC 60479-1.
Below C1: no fibrillation;
Above C1 up to C2: low risk of fibrillation (up to 5% of probability);
Above C2 up to C3: average risk of fibrillation (up to 50% of probability);
Above C3: high risk of fibrillation (more than 50% probability).
Figure 20 IEC 60479-2: Threshold of ventricular fibrillation
The OICA proposal was evaluated with this background in mind. The justification provided in
the OICA proposal for the energy option is only applicable for shock durations up to 10 msec
(Table 20 of IEC 60479-2). Per the OCA proposal, body current of 500 mA is permitted for
shock duration 10 msec or shorter and is considered safe from ventricular fibrillation. For shock
duration greater than 10 msec, Figures 20 and 22 of IEC 60479-1 apply (10 msec duration body
current of 200 mA is at the border of zone DC-2 and DC-3 and that of 500 mA is at the border
of zone DC-3 and DC-4, which are considered dangerous).
The OICA approach to determine minimum allowable energy levels would permit body currents
of 500 mA for shock duration of 10 msec to prevent ventricular fibrillation (border of zone DC-3
and DC-4). In contrast, the electrical isolation option of FMVSS No. 305 does not allow more
than 10 mA DC body current which is in the middle of zone 2 (involuntary muscular
contractions with no physiological effect). The risk level addressed by the energy option
proposed by OICA is significantly higher than that in the electrical safety requirements in
FMVSS No. 305.
The OICA proposal permits 0.2 joule energy as a standalone option without any specifications
on the shock duration or the type of high voltage source it applies to. So per the OICA proposal,
a capacitor with a discharge time longer than 10 msec can meet the 0.2 joule energy option that
permits 500 mA through the body which is significantly more dangerous (at the border of zone 3
and zone 4) than the other three options for electrical safety: electrical isolation, low voltage, and
protection against direct/indirection contact options (which are in zone 2). For these reasons, the
agency is not considering the energy option.