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RE: Fuse/Circuit Breaker

To: <triumphs@autox.team.net>
Subject: RE: Fuse/Circuit Breaker
From: "Randall" <tr3driver@comcast.net>
Date: Fri, 1 Apr 2005 10:13:39 -0800
> But discussions of fusing quickly evolve into a philosophical discussion
> about how much you want to spend and how finely defined is the
> protection.

I don't know about that ... you can do a whole lot of fusing on a Triumph
before reaching that decision.  Just making sure that every wire in the
harness is protected by a fuse matched to the size of the wire (so that a
short will blow the fuse rather than smoking the wire) takes quite a few
more fuses than the factory used.

> But adding a protection to the main brown wire is pretty easy,
> all you have
> to do is find the source.  Oops, do you fuse the battery source or the
> generator source?  Hmm.

Fusing the generator is a bad idea, IMO, and unnecessary since it has it's
own limitations.  The stock generator won't generate much more than 30 amps
even into a dead short.   And if there is a short in the main power circuit,
the engine is going to die (no ignition), thereby disabling the generator
(or even that high-output alternator).

So, the place to add protection is clearly at the battery source for the
smaller wiring, which on a TR2-4 is the starter solenoid.  Assuming you
aren't going for the concours look, my suggestion would be to add a fusible
link where the brown wire attaches to the solenoid.  I never got around to
doing this on my last TR3, but the 'new' one will have it.

If you were going to use a fuse or breaker, I'd want it to be a slow blowing
type (thermal breaker rather than magnetic).  That way it won't blow for
momentary overloads.  After all, the goal is to protect the wiring, and the
wiring will handle momentary overloads just fine.

Randall




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