OSHA always provides a specific list of violations. They don't just ask about whether something is under 50 volts. They either cite a violation or not. If they didn't, it's fine. If they did, you'll get a notice in the mail within a couple of weeks with everything spelled out.
To answer your question, OSHA considers anything under 50V to be non-hazardous. So if there are exposed energized parts or fuses that need to be changed hot or even light bulbs that need to be changed hot, or something that's not grounded, it's okay under 50 volts but not okay at 50V or more. That's the only 50V distinction I know of.