The three rules
Rule one: never work on a live high-voltage system. Follow the manufacturer's high-voltage disable procedure (usually pulling a service plug or MSD) and then verify zero voltage at the disconnect points with a CAT III-rated meter before touching anything. Rule two: use Class 0 rated insulating gloves inspected daily. Rule three: no jewelry, no metal watches, no metal-framed glasses in the work area.
What DC voltage does to the body
AC voltage causes muscles to spasm and release. DC voltage causes muscles to lock, so a hand that touches a live 400-volt DC bus bar cannot let go. Contact times of even 50 milliseconds at these voltages can stop the heart. This is why the disable-and-verify procedure is not optional.
After a collision
Do not touch any orange cable on a wrecked EV. High-voltage insulation can be compromised without visible damage. Follow the manufacturer's collision-response procedure, which usually involves waiting a defined discharge period after disconnecting the service plug. Uber and tow drivers have been electrocuted skipping this step.