Wow. some interesting responses there, and yes saprkyinak that is an OSHA requirement.
Don has it right, LOTO, verifiy no voltage (Check your meter before and after on a known live source. Shock and Arc flash protection is required to be worn by the QUALIFIED person 9per NFPA 70E) to do the voltage check. Also if there is a chance oh induced voltages (Inductive coupling) or stored energy sources (Like a capacitor in a VFD) the protective grounds must be applied that are rated for the available fault current in the system before touching the conductors.
OSHA 1910.269 and NFPA 70E
