Question: “Safety manuals overview or detailed; What is best?”
Answer: Think if you proved one or the other…which version do you think will be most read by your intended audience? There’s your answer. But why not have both, to satisfy those folks inclined to go deeper? Write the detailed version first and use that to create the overview.
Personally, my suggestion would be to hit the high points, with consideration for each end of your audience spectrum, perhaps working with colleagues to peer review materials; you’ll never know what you may find.
For most organizations, you’ll find that attention is in short supply, particularly when it comes to safety. Not sure what your workforce demographics are, but that kind of information does influence the call here. It’s all about your people, truly. Less is more, but only if you’re able to communicate adequately.
There’s an art to presenting technical information in way that’s engaging—this is what technical writers do, as a profession. In the past, the assistance of a technical writer for written safety programs was greatly beneficial for one organization I’m familiar with. That’s something to consider.