Does OSHA Require Low Voltage Work To Wear Hard Hats, Reflective Vests, Etc...

If you are on a jobsite that is being run by contractors who abide by OSHA regs then yes

If the voltage is 49 volts or less then generally no. If it's over then it must first be de-energized which may prompt PPE and lock-out requirements etc.

Also, if your boss says it's required, then it's required.

'OSHA Regs' apply different for different types of work. For example, Construction sites have their own regulations - 'OSHA' is CFR 1926.  But CFR 1928 is OSHA for agriculture/farming.

There are also 'State' OSH acts that supersede federal OSHA.  Jobsite or Facility rules can supersede both regs too is they are more stringent.

All that is a disclaimer to say that level of PPE (hardhats, vests, etc) sounds like a jobsite requirement, and should be followed.