STUPID QUESTION No 4

Because automobiles have a lot more fuses, and the color coded plastic fuses allow for a smaller denser fuse box as well as quickly identifying rating by color.

Stereo equipment fuses generally blow at much lower currents, so use thinner wire that would corrode and reduce the rating. Plus they're often at mains voltage (or much higher than 12V) so a shield is a good idea.

Clifford Heath

** Flat blade fuses and matching holders are relative new comers specifically designed for automotive and other 12V DC use - they have taken over in that job from glass tube fuses in the last decade or so.

Stereo equipment makers have no reason to change.

.... Phil

It wasn't always like that though, at one time the glass fuses in cars were standard. They weren't in cylindrical holders, they laid flat in a fuse block.

But you are correct about the count/density being a factor. I had a 1964 Buick which only had 8 or 9 fuses total. There just wasn't much in the electrical system to protect.

On the other extreme, like the 1997 Lincoln Mark VIII, there is something like 35 fuses for all the accessories. It's only about a 4"x4" square on the side of the dashboard, easy to get to, easy to examine.

35 glass fuses would take up a big chunk of real estate under the dash and would probably be a nightmare to access.

If you are asking why they don't use the colored plastic ones in the stereo hardware, I think the answer has to do with the difference of how a fuse behaves with 12v or 120v/240v passing through them.

The glass fuses usually vaporize when they blow, reducing the chance of an arc or flash to reseal the link. The 12v fuses just have a weak, short element that blows between two points.

I guess there is some possibility of the fuse "re-sealing" itself under certain circumstances (none of which I can think of).

-bruce snipped-for-privacy@ripco.com

the 400 watt Kenwood amp mounted on the van's metal partition fuses with a blade type auto fuse.....on DC

on DC. My unconscious assumption was modern plastics were capable of AC 110V.

the air clearance in a glass fuse is prob commercially economic visavee capable plastics.

my designed in 1946 PV544's manual boasts a one page electric schematic. The 2008 Ford E250 runs 0ver 100 pages for 'problem solving' with equipment. IE poke meter into connector hole there >

bought an analyzer....

1. Glass and ceramic cylinderical fuses have the fuse wire soldered to the end caps. If you were to do the same thing using a plastic tube, the heat from the soldering operation will melt the plastic tube.
2. Automotive style plastic fuses, also known as blade or spade fuses, use a stamped fuse wire. You can only make a stamped wire so thin before it falls apart. The minimum value I could find for cartridge fuses is 0.080A. The minimum value I could find for automotive fuses is 1 amp: Speaker protection fuses need to be fairly low current:
3. Glass and ceramic cylinderical fuses are typically rated at 117 and 230VAC insulation. Plastic automotive fuses are 32v and 58v. Note that it is possible to obtain UL listed blade fuses: but not for use at 117/230VAC.
4. For stereo equipment, glass fuses can be chrome or gold plated to make them look "cool" and expensive. Same with gold and chrome plated cartridge fuse holders. Plastic fuses are comparatively ugly.

--
Jeff Liebermann     jeffl@cruzio.com 
150 Felker St #D    http://www.LearnByDestroying.com 
Santa Cruz CA 95060 http://802.11junk.com 
Skype: JeffLiebermann     AE6KS    831-336-2558

I didn't look hard enough. Make that 0.062A minimum in 3AG size: Note that it has a resistance of 24.7 ohms which much too high for many applications. There are also fuses on the list down to 0.010A, but they are listed as obsolete.

--
Jeff Liebermann     jeffl@cruzio.com 
150 Felker St #D    http://www.LearnByDestroying.com 
Santa Cruz CA 95060 http://802.11junk.com 
Skype: JeffLiebermann     AE6KS    831-336-2558

and reason for blades is space n durability.

2 designs types, a field of viable differences

know Crutch ? also usually carries GT battery posts