Hi Catherine, I believe Health & Safety records need to be retained for 7 years.

I don't believe there is a legally required time-frame for keeping non-notifiable incident records. I would consider how long they are useful for your business first and foremost.

Due to all of our records within our company having our logo on them we hold them for 5 years.

Not that we want to, but ours get kept for ever. That's because it all gets scanned / electronically recorded against an employee. And once done I can't be bothered deleting. One day some Privacy Act botherer will knock on my door and remind me I can only keep personal information for as long as I have a purpose for holding it.

In terms of actual time frames you probably have:
1 year - to cover the time an employee has to lodge an ACC claim.
3 months if a person wants to bring a safety related personal grievance.
7 years if it relates to a taxable payment to an employe.
12 months for the purposes of the Worksafe prosecution limitation period
2 years in relation to a private prosecution
5 years, if as a PCBU you have a notifiable event

30 years for substance exposure - e.g Asbestos

At the Central Districts Field Days Work Safe said I only needed to keep notifiable incident information. But Andrews list in the comments above seems really helpful