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Shouldn't this have blown the fuse ?

PostPosted: Thu Sep 26, 2019 11:09 pm
by LaikaTheDog
20190926_173558.jpg and
Melted

Also melted the fuse housing...

Was pulling out the steering column to do the bushes and found this hidden in the rats nest of wire.

Re: Shouldn't this have blown the fuse ?

PostPosted: Fri Sep 27, 2019 12:40 am
by Slowtus
Looks 'blown' to me.

The obvious distress shown on that fuse may have been wholly unrelated to the connection it is/was (may have been?) looking to protect.

Re: Shouldn't this have blown the fuse ?

PostPosted: Fri Sep 27, 2019 8:20 am
by 512BB
Just connect up a continuity tester to the two spades to confirm if the fuse has blown or not.

Leslie

Re: Shouldn't this have blown the fuse ?

PostPosted: Fri Sep 27, 2019 8:29 am
by JonB
What was it connected to?

Re: Shouldn't this have blown the fuse ?

PostPosted: Fri Sep 27, 2019 10:46 am
by LaikaTheDog
Fuse was still intact and was the source of the heat, it was connected to the dashboard lighting in a +2

Re: Shouldn't this have blown the fuse ?

PostPosted: Fri Sep 27, 2019 11:13 am
by seriouslylotus
Probably (but not necessarily) caused by a hi resistance between the connector and the fuse blade.
This creates heat but not particularly a hi current flow, so wouldn't blow the fuse.
Was it on the feed side or the out put side of the fuse?

Re: Shouldn't this have blown the fuse ?

PostPosted: Sat Sep 28, 2019 10:06 am
by mark030358
Have to agree with the last post, a poor connection. Probably a Chinese fuse....
Cheers

Re: Shouldn't this have blown the fuse ?

PostPosted: Sat Sep 28, 2019 7:04 pm
by Esprit2
What amp rating was that fuse? And was that rating the proper British/ Lucas rating, or a physically similar looking, but very different US Federal / BUSS rating.

A Buss 17 amp is roughly equivalent to a Lucas 30 amp fuse.

Do NOT use Buss fuses in vintage British cars without taking into consideration the difference in the rating systems. For the same fuse, the BUSS rating is for the current it can carry continuously, and the Lucas rating is for the current that will cause it to blow immediately.

That's like giving a dimension as 36.
:-/
Okay, is that inches or millimeters?

In broad terms, the BUSS rating is approximately one half of the Lucas rating.

If you use a 30 amp 'BUSS' fuse in a circuit that calls for a 30 amp 'Lucas' fuse, the wiring will melt down before the fuse blows.

Regards,
Tim Engel

Re: Shouldn't this have blown the fuse ?

PostPosted: Sat Sep 28, 2019 7:30 pm
by Elanman99
Bussman manufacture many type of fuses to many different specifications so it a bit of a simplification to conclude that the fuse pictured is actually a Buss fuse and has rating that may or may not be comparable with Joe Lucas fuses.

The blade type fuse is not Lotus original and its failure (caused by overheating) might be that whoever carried out the modification did not fit a correctly rated fuse for the load it was feeding. As far as I know all fuses will carry a higher current than its marked value before it blows, how long it carries that higher current is what matters but it probably varies from microseconds to hours!

Ian

Re: Shouldn't this have blown the fuse ?

PostPosted: Sat Sep 28, 2019 8:15 pm
by Esprit2
Elanman99 wrote:Bussman manufacture many type of fuses to many different specifications so it a bit of a simplification to conclude that the fuse pictured is actually a Buss fuse (Snip)...
My opening line questioned what the fuse was... there was no jump to a conslusion. On the other hand, you read what you wanted to read, and jumped to your own conclusion... on my case. You're guilty as you charged.