Glass Fuses

[Gwylan]

Clearing our a locker I have collected a considerable collection of glass fuses.
They are now neatly sorted into their various ratings and speeds [ fast, slow etc]

I understand the markings, amp ratings and fast, slow etc.

Generally replace like with like - that is assuming that whoever installed or replaced the fuse last used the right type and rating.

What I do not understand is that they are rated at 240 or 250 volts.
How do I translate that to 12 volt circuits?
There are some circuits like the heating and fridge that are not currently fused and I'd like to have a rule of thumb to calculate whist fuse I need.

For example the fridge draws a max of about 5A @ 12 volts - what size fuse do I need?

 

[nigelmercier]

What I do not understand is that they are rated at 240 or 250 volts... For example the fridge draws a max of about 5A @ 12 volts - what size fuse do I need?

The voltage rating is just the maximum for which they have been tested, ignore it.

If the fridge really does draw 5A max, even on start up, then you can use a 5A fuse. Some electronic gear has a fuse rated to protect the device, but in general the fuse is to protect the wiring.