question about fuses

[freddiecas]

my amps have small glass 4A 25mm fuses at the mains input, these have a single fine wire between the contacts.

I have some other 4A fuses which have a thin core and spiral of thicker wire between the contacts which I suppose to be slow blow?

However both have T4AL embossed at the contact end.

Is there not a different code for quick/slow blow, and are the slow blow type safe to use if the amp was supplied with I assume quick blow with the fine wire?

thanks for replies

[alb]

Fast blow fuses are usually marked with F on the cap.
Slow blow with a T. (time delay)

The straight or spiral wire is possibly irrelevant, as T type fuses can take either form.
You have a T type fuse which is designed to withstand extra current at switch on.

[freddiecas]

thanks, that clears it up