Posted By David Bannister
I would suggest that a trivial incident is one that may require basic first aid (clean up bleeding, plaster, remove splinter etc) and allows an immediate return to work, or no follow-up treatment. The likelihood of a more significant injury to have occurred was nil. No formal investigation needed.

A minor incident may involve a trip to the local NHS casualty unit and treatment as an out-patient, returning to work for the next shift. May possibly have been a worse incident. Formal investigation indicated.

The next category would be identical to a basic "RIDDOR reportable" followed by a major injury: as RIDDOR etc.

If you wish to include a near-miss or near-hit then this is a no-injury incident that may have (but for luck) been much worse eg nearly getting hit by a fork-lift truck, nearly getting hit by a falling item, failure of containment of a hazardous substance etc. Formal investigations here may produce real benefits in identifying system weaknesses.

Hope this helps, but others will certainly classify in their own ways.

Posted By Andy Brazier
I'd say trivial is one that does not need anything from the first aid kit. May be a scratch that needs to be washed, a minor strain etc.

I'd be thinking that if someone needs to go to casualty that it is more than minor, but it is all relative.

In making your classifications it is vitally important that you consider the potential as well as actual consequences. There is usually a great deal of luck that means people are not harmed as badly as they could have been. If the potential was great a full investigation and analysis should be carried out even if the actual consequences were only trivial.