[TR] TR2-3 electrical melt downs

[DAVID MASSEY]

 Keep in mind that these wire harnesses, like the car as a whole, was designed to a budget.  These harnesses had three (count 'em, 3) fuses.  As such some items were unfused like the headlamps and the coil.  And those things that are fused shared a fuse so the fuse had to be sized to carry the current for everything on that circuit.  But the wires were sized for the particular load.  A thinner wire will have a nigher resistance and under  short-circuit conditions the current can be limited to a level that will not blow the fuse but the current will cause enough heating to cause the insulation to melt.
Another factor against us is the age of the harness.  The connector contacts get corroded and will get hot under normal circumstances.  Wire strands can fatigue and break within the insulation again resulting in overheating under normal use.  The insulation gets stiff and cracks exposing the wires within.  Lots of potential failure modes here.  

Compare this design to those found in modern cars you will see dozens of fuses.  Sure there are a lot more electrical items but most things have their own fuses.  This means you can size the fuse more appropriately for the wire used to power that device.  Also the connectors used are water tight and don't corrode as quickly.  Also, they are, on the whole, a lot younger and therefore retain more of their original integrety.
But a fresh works well enough so if you fear a melt-down a new harness may be a good investment.
 
Dave 

 
 
-----Original Message-----
From: bill beecher <notakitcar at yahoo.com>
To: Tom Householder <trhouse at columbus.rr.com>
Cc: Triumphs at Autox.team.net daily digest <triumphs at autox.team.net>; FOT List <fot at autox.team.net>
Sent: Tue, Jun 23, 2020 8:52 am
Subject: Re: [TR] TR2-3 electrical melt downs

Have a friend with a TR6 that had a significant meltdown behind the dash.  I should think, given the right set of weaknesses, most any section could melt. 
Bill B

Serenity Now......

On Jun 23, 2020, at 4:52 AM, Tom Householder <trhouse at columbus.rr.com> wrote:

Over the years I have experienced and seen harness melt down in the looms to the tail lights .. anyone ever had an under dash melt down?

Trying to answer a question asked of me. 

Tom 
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