OSHA and NFPA 70E Chapter 1 use 50 Volts as a threshold for requiring establishing an electrically safe work condition.

However 48V DC battery systems can have a float voltage upwards of 58 Volts DC.

...and NFPA 70E Article 320 Safety Requirements Related to Batteries and Battery Rooms sets the voltage threshold for batteries at 100 Volts DC. Chapter 3 can supplement or modify the requirements of Chapter 1.

With all that, here comes the question.

For 48Vdc battery systems, what voltage threshold do you use to require de-energizing?
50 Vdc
100 Vdc
something else
it depends
no DC

I have met a few mechanics who are missing their ring finger. They forgot to disconnect the car battery before changing out a starter and their ring shorted out the power terminal on the starter to the frame or the engine. Instant anmputation. Always disconnect no matter what voltage.