We have a glass fuse for a 12v lighting circuit that has "Siran No. F 13 4A" written on paper inside it. The circuit takes 5.5A at the moment with all the lights switched on without the fuse blowing. Can someone tell me what this is rated at? It seems to be a fast blow (F) so can it really be a 4A?
I figure my options are
13A (so what does the 4 mean?)
13.4A
4A (why is it still working at 5.5A?)
Thanks for reading, Steve
Edit: Images added as requested. Fuse shown with left side in holder