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Lucas fuse ratings - store this info for the future!

To: "1-TR8-list" <tr8@mercury.lcs.mit.edu>, "1-Triumph List" <triumphs@autox.team.net>
Subject: Lucas fuse ratings - store this info for the future!
From: "Odd Hedberg" <odd@triumphclub.se>
Date: Sat, 10 Jul 2004 01:21:17 +0200
Thread-index: AcRlz+lN0veYNWs8QOutleDYZL9/wQAOg6/w
OK friends, 
Wayne's mail made me think - so I went out to my TR8 and took 
out my little stash of old original Lucas fuses [from the era 
when they were labelled with both of their current ratings]:

A Lucas fuse is rated by what current it would blow at. 
Ordinary automotive fuses are rated by what current you can 
draw WITHOUT blowing them, or the maximum continuous current. 
They don't really specify at what current they'll blow...

Anyway, these old Lucas fuses of mine have both the Lucas 
"will blow at" rating, and the maximum continuous current 
rating, i.e. the normal rating labelled on them. 
[Or rather in them, because it is a small paper strip inside 
that carries this info. The more modern Lucas fuses have the 
info printed on the glass tube in an abbreviated form.]

So here's your equivalents:

Lucas 50 amp - continuous 25 amp
Lucas 35 amp - continuous 17 amp
Lucas 25 amp - continuous 12 amp
Lucas 20 amp - continuous 10 amp
Lucas 15 amp - continuous  8 amp
Lucas 10 amp - continuous  5 amp
Lucas  2 amp - continuous  1 amp

See the trend here? 
Each fuse is actually good for a continuous current that's 
roughly 50% of it's Lucas rating.

BUT!
Another, and just as important, issue to take into account is 
the fact that the Lucas fuses have a different physical size 
as compared to the standard item.  [Who would be surprised!?] 

The Lucas 1/4" diameter fuse is 1 and 5/32" [~29.4mm] long, 
while the standard 1/4" fuse is 1 and 2/8"  [~32.0mm] long. 

This makes it more than a tight squeeze - loading the fuse holder
plastic with undesired stress if you force a standard fuse into 
the Wedge fuse block... 

Best regards
/Odd 

-----Original Message-----
> Didn't someone post a conversion table or something to get you
> close to the correct rating?  Installing a fuse with too high
> a rating could be inviting melted wires and a possible fire.
> You don't want that.





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