As I understand it in the USA if I, a normal citizen, walking by a stranger's home and witness them suddenly get electrocuted or otherwise seriously harmed I'm allowed to enter their home to try to render aid, even uninvited, since I have a reasonable belief they would prefer me to come into their home under those circumstances.
I'm wondering where the line is drawn for that. I presumably can't barge into a stranger's home because it looks like they are having a bad hair job and I need to give them a perm this instant. How serious would the need have to be before I could justify entering their home? If I see someone appearing to be about to commit suicide can I reasonably barge in to try to stop them for example, even though presumably at that moment they did want privacy to continue following through with their suicide?
On a related note when, if ever, would I be authorized to break into a home that was otherwise locked to render aid?