Using automotive fuses

[Helmholtz]

You would also not believe how many times I have seen a good fuse that does hot have continuity.

I guess you mean that with some fuse types one can't tell from the looks if it's good.

Whenever you can measure a voltage across a fuse, either the fuse or its contacts are bad.

Actually I don't understand the discussion about automotive fuses as the ones I know are completely different (including the holder) from standard equipment fuses.

[DrGonz78]

Actually I don't understand the discussion about automotive fuses as the ones I know are completely different (including the holder) from standard equipment fuses.

These fuses are automotive but not as common. I think they are for some older models.

[Mick Bailey]

Older automotive fuses are close enough in size to regular 0.25" x 1.25" mains fuses to be interchangeable and are available in ceramic or glass. There are also some types that will fit in a 20mm fuse holder. Plastic blade and bullet fuses won't fit any regular mains fuse holder.

Having been in the business of repairing equipment for a living, liability is a serious concern and I've always replaced fuses with the correct type and rating if found to be incorrect.

[Helmholtz]

These fuses are automotive but not as common. I think they are for some older models.

Thanks.
Never saw those in a german car.
What makes them attractive to use elsewhere? Price, availability?
Should be interesting to compare specs (like voltage and I²t value) to standard fuses.

[Tom Phillips]

Older automotive fuses are close enough in size to regular 0.25" x 1.25" mains fuses to be interchangeable and are available in ceramic or glass...

Yes. Those fuses are type "3AG" and the "AG" stood for "Auto Glass."

[Helmholtz]

Yes. Those fuses are type "3AG" and the "AG" stood for "Auto Glass."

Ok, but this article https://www.fusesunlimited.com/products/automotivefuse
says that automotive fuses are rated only up to 80V.

[g1]

What makes them attractive to use elsewhere? Price, availability?

It was mostly availability. It used to be that you could always find standard 1.25 inch auto fuses at any garage or gas station. Usually too high value, but they fit, so people used them. I still get stuff that has 10 or 20A 32V fuses where there should be 4A or less.

[Tom Phillips]

Ok, but this article https://www.fusesunlimited.com/products/automotivefuse
says that automotive fuses are rated only up to 80V.

I should have clarified that the "3AG" is a size and case construction specification. It doesn't indicate electrical parameters.
Ancient information to many people. Like vacuum tubes.

[Helmholtz]

I should have clarified that the "3AG" is a size and case construction specification. It doesn't indicate electrical parameters.

And obviously it doesn't indicate the designated use either.

E.g.: https://cdn1-originals.webdamdb.com/...ASI2IOLRFF2RHA

[g1]

And obviously it doesn't indicate the designated use either.

E.g.: https://cdn1-originals.webdamdb.com/...ASI2IOLRFF2RHA

Quite interesting that for the particular slow-blow type, at 135% capacity it can take up to an hour to blow.

[Axtman]

"What did you get your degree in?" Me, "Fuseology!" ;-)

Everything you ever wanted to know about fuses:

https://cdn1-originals.webdamdb.com/...ASI2IOLRFF2RHA

[georage]

is it true that when using a dc fuse for ac that you can safely increase the voltage by 1.41?

[Axtman]

I think I just answered my own question. I found this on the Cooper Bussman webpage about fuses.

[Helmholtz]

Actually I didn't understand your original question as I thought it was clear that the voltage rating must be sufficient for the application.
I wondered if there even are 125V automotive fuses.

BTW; a 125V fuse may be fine as a mains fuse but not as a HT fuse.

[Steve Blackdog]

I am late to the party with this thread, but it never ceases to amaze me how many people will ‘cure’ an appliance that keeps blowing 5A fuses by swapping them for 13A fuses!