energyQ:  My staff are digital instrumentation technicians who will never see any voltages greater than 120VAC. What entity requires training for these type individuals (right now, we're going to the training because our Electrical group says we need to, but can't prove a basis for the training, and because it makes sense from a safety point-of-view)? What is the training actually required for these type individuals?  Does initial training differ from refresher training? How often is refresher training required?  
A:  Instrument techs are normally "exposed to" voltages higher than what they commonly "work on". This is the key.  The first issue is shock and understanding when they might be "exposed to" 480V shock exposures; (usually older equipment is the culprit where there is supply and control voltage in the same compartment). 
The second issue is 480V arc flash. We have several instances where workers are working on control wiring in MCC's and a 120V minor arc flash turned into a major 480V arc flash when it ionized air gap in the 480V.
OSHA requires training of all "recognized hazards". Shock on 120V kills more than 12,500V according to NIOSH. Arc Flash hazards are greatest on 480V systems. There is likely little or no arc flash exposure on 120V systems unless the worker is also "exposed to" 480V. 

I'm for meeting OSHA requirements on training and not over doing it, BUT I have investigated a few incidents of dead IE/I&C techs who thought they knew everything and had a 480V arc flash, so this work is a hazard. Even 120V control wires can kill in the right conditions. Safety training is law, not just an internal (company) compliance requirement.
Working on 120V is a hazard often ignored. Specific training is required for ALL "qualified persons" by OSHA. It doesn't spell out what you have to train on specifically but they must be trained. 
We worked a case of an untrained and unqualified supervisor in Arkansas forcing an electrician to do work unsafely which resulted in the electrician's death. That supervisor had not attended training.  He lost his job and was also investigated for homicide charges. 

Source: Hugh Hoagland,, 13113 Eastpoint Park Blvd., Suite E, Louisville, KY, 40223; PH: 502-333-0510;