Wow, this is wrong in so many ways. Firefighters are trained to NEVER, under any circumstances, cut any orange cable in a EV/PHEV/Hybrid.
If the car is "off", cutting the 12V battery cable will give some safety since there will be no voltage present outside the high voltage battery itself. To be totally sure, removing the service plug will ensure the battery is totally isolated, but locating it and knowing how to remove it can be difficult in a wrecked vehicle, or if there is a fire.
All EV owners should be aware of the location of the MSD - Main Service Disconnect so they can assist emergency responders if necessary.
On the leaf (2011-2115) it is located under the small triangular panel in the rear seat area, directly behind the front armrest.
Lift the patch of carpet, remove the 3 thumbscrews and then lift the handle on the orange plug and pull it free.
Don't remove the orange plug unless you intend to totally disable the vehicle as it may require a dealer to reset the system afterwards, but it's good to know where it is located. http://www.evsafetytraining.org/resourc ... issan.aspx