EVSTF-06-06e
United States Comments to proposed requirements for
EVS GTR on “protection against water”
Background:
At the 8th EVS GTR IWG meeting in Changchun, members of TF-1 continued to discuss
proposed requirements and test procedures (EVS-08-17) to address the safety performance of
EVs during in-use in events of flooding and vehicle washing. As an action item, members were
requested to provide comments on the overall proposal, specifically, water depth (10cm) and
vehicle speed (20 km/h) for the drive test.
Recommendations:
1. We agree with the 10 cm water depth and 20 km/h vehicle speed for the flood test.
Below is a summary of recommended road closure in the U.S. due to road flooding.
2. We recommend that after the test, all electric powered vehicles maintain adequate
electrical isolation regardless of whether electrical isolation monitoring system is available. We
recommend the following changes to 5.X1:
5.X.1
Protection against water effects
When the vehicle is subject to the tests in 6.X, within 5 minutes after each
exposure, and with the vehicle still wet, the vehicle shall comply with
isolation resistance requirements in 5.1.1.2.4. Additionally, 24 hours after
completing the tests in 6.X, the vehicle will comply with isolation
resistance requirements in 5.1.1.2.4 and exhibit no evidence of fire or
explosion. Protection against water effects shall be provided by an
isolation resistance monitoring system, or by protecting or shielding the
voltage class B equipment from exposure to water. If the vehicle is
equipped with an isolation resistance monitoring system, the requirements
of 5.X.1 1 shall apply. If the vehicle is not equipped with an isolation
resistance monitoring system, the tests given in 6.X.1 shall be performed
in order that the requirements of 5.X.1 2 are met.
5.X.1 1
If an isolation resistance monitoring system is provided, and the
isolation resistance less than the requirements given in 5.1.1.2.4 is
detected, a warning shall be indicated to the driver.
The function of the on-board isolation resistance monitoring system
shall be confirmed as described in 6.1.2.
If the test procedures specified in 6.X.1 are performed, just after each exposure, and
with the vehicle still wet, the vehicle shall then comply with isolation
resistance test given in 6.1.1, and the isolation resistance requirements
given in 5.1.1.2.4 shall be met.
In addition, after a 24 h pause, the isolation resistance test specified in
6.1.1 shall again be performed, and the isolation resistance
requirements given in 5.1.1.2.4 shall be met.
Discussion:
In the U.S., there are no federal regulations regarding road closures due to flooding. Instead,
local jurisdictions have the authority to close flooded roads for safety due to a variety of reasons.
However, typical advice to drivers is “do not drive through any more than 4 inches (10 cm) of
moving water, or 6 inches (15 cm) of standing water.” Based on several parameters such as
vehicle underbody carriage, vehicle speed and water speed, a vehicle could experience the
following scenarios:
 Just 6 inches (15 cm) of standing water – sometimes less – can be enough to cause engine
stalling. The vehicle engine can suffer serious and expensive damage if it ingests water.
 In approximately 1 foot (31 cm) of water, a typical car can begin to float and, as traction is
lost, so is steering control. If the water is flowing, a vehicle could literally float away.
 At 2 feet of water, even larger vehicles such as pickup trucks and SUVs are in danger of
floating away.
http://www.theweathernetwork.com/us/news/articles/think-you-can-make-it-through-floodwaters-think-again/58279/
Some additional links regarding flooded roads:
http://www.wheels.ca/news/heres-why-you-should-never-drive-through-flooded-roads/
http://www.weather.com/safety/floods/news/flash-flooding-vehicle-danger-20140717
Furthermore, while certain roads in rural/undeveloped areas in the U.S. with low volume traffic,
such as roads in National forests, allow vehicles to transverse a stream, design guidelines
recommend building a culvert or bridge over stream crossings with water depth of 15 cm or
greater. JRC noted in their comments, “.. 10 cm of water may be relatively easily formed on
Dutch secondary roads and in tunnels under railways and viaducts. These roads are less often
closed and, therefore, it is the usual practice to drive, albeit at a lower speed, through flood
water. Also, 10 cm of water on a highway is less frequently but regularly (approximately 1 to 3
times a year) observed in The Netherlands.”
The above information indicates that 10 cm water depth on roadways is regularly observed in
certain regions and that 15 cm of water depth is the maximum threshold above which vehicles
are not permitted to drive through. Thus, driving thru a flooded road at10 cm water depth is
reasonable and a likely occurrence. Therefore, we believe that the vehicle remain functional and
not lose electrical isolation while driving through 10 cm of water, regardless of whether an
electrical isolation monitor system is available (the GTR only requires fuel cell vehicles to be
equipped with electrical isolation monitoring system). Additionally, we believe that it is
important that driving through 10 cm of water does not cause a thermal event within the battery
pack.