Fuse: Fast or Slow Blow???

ShanksKop

Club Member
Hi All,

No idea if this is a stupid question.

Which work better for vehicles in general (I have a 280z) slow blow or fast blow?

Is there a noticeable difference in quality?
If so where can I get good quality ones from?

I had a blown dome light fuse which I replaced not so long ago and the indicator fuse went yesterday (luckily a spare one in the glove box). Hopefully nothing too concerning.

Might replace the lot, as fuses tend to be quite inexpensive. As far as I understand I would need 10 x 10 amp and 5 x 20 amp.

Thanks as always
 

toopy

Club Member
I thought the glass fuses used in these cars are supposed to be fast blow, the fusible links on the other hand are considered to be more slow blow.

Before replacing a blown fuse, always clean the fuse holder contacts to avoid any crud causing resistance with the new replacement. Also have the fuses popped cleanly or do they look like they have suffered from prolonged heat damage as well?
It could be that there is a lot of resistance in the circuit, which causes the fuse to get very hot, but not enough to instantly blow it as a short circuit would. A fast blow fuse is designed to blow at twice its rated amps, so a 10 amp fuse will pop at approx 20 amps, but may soldier on for quite a while at say 18 amps before heat stress causes failure!
 

ShanksKop

Club Member
Thanks for your response Toopy.

A bunch of fast blow picked up. I'll need to get back to the car to see how the last couple of fuses have blown, but I'm sure it was a clean break as much as the strip between both points had blown.

On a side note anything in particular you clean your fuse contacts with?
 

toopy

Club Member
Just some generic electrical contact cleaner spray, was from Screwfix i think.

You can also use emery paper or perhaps wire wool, but disconnect the battery first if using the wool!
 
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