> and anything you can do without blowing that fuse won't damage the grid
That's what you'd think. But I have actually done damage to the grid and had that fuse still in one piece. I accidentally connected the -HV line of a neon light installation to ground. After I could see again I realized the power had gone out. I called my boss (landline still worked) who lived more than a kilometer away from the workshop and there too the power had gone out. It turned out my little accident had put a good chunk of the eastern part of Amsterdam out of commission and the fuse was just fine.
Fuses react to current, not to power and when you dump a high enough voltage back into the grid your fuse might not blow before you cause something further upstream to trigger to protect the rest of what's connected.
That's what you'd think. But I have actually done damage to the grid and had that fuse still in one piece. I accidentally connected the -HV line of a neon light installation to ground. After I could see again I realized the power had gone out. I called my boss (landline still worked) who lived more than a kilometer away from the workshop and there too the power had gone out. It turned out my little accident had put a good chunk of the eastern part of Amsterdam out of commission and the fuse was just fine.
Fuses react to current, not to power and when you dump a high enough voltage back into the grid your fuse might not blow before you cause something further upstream to trigger to protect the rest of what's connected.