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Re: [TR] TR2-3 electrical melt downs

To: "notakitcar@yahoo.com" <notakitcar@yahoo.com>, "trhouse@columbus.rr.com" <trhouse@columbus.rr.com>
Subject: Re: [TR] TR2-3 electrical melt downs
From: DAVID MASSEY <dave1massey@cs.com>
Date: Wed, 24 Jun 2020 14:37:56 +0000 (UTC)
Cc: "triumphs@autox.team.net" <triumphs@autox.team.net>, "fot@autox.team.net" <fot@autox.team.net>
Delivered-to: mharc@autox.team.net
Delivered-to: triumphs@autox.team.net
References: <10B1B3CB-F270-4282-A344-C4643EDC0119@columbus.rr.com> <9EDEDDAC-666C-4C1F-A1B5-68449C1A85A0@yahoo.com> x64; rv:77.0) Gecko/20100101 Firefox/77.0
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 Keep in mind that these wire harnesses, like the car as a whole, was desig=
ned to a budget.=C2=A0 These harnesses had three (count 'em, 3) fuses.=C2=
=A0 As such some items were unfused like the headlamps and the coil.=C2=A0 =
And those things that are fused shared a fuse so the fuse had to be sized t=
o carry the current for everything on that circuit.=C2=A0 But the wires wer=
e sized for the particular load.=C2=A0 A thinner wire will have a nigher re=
sistance and under=C2=A0 short-circuit conditions the current can be limite=
d 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.=C2=A0 The connector co=
ntacts get corroded and will get hot under normal circumstances.=C2=A0 Wire=
 strands can fatigue and break within the insulation again resulting in ove=
rheating under normal use.=C2=A0 The insulation gets stiff and cracks expos=
ing the wires within.=C2=A0 Lots of potential failure modes here.=C2=A0=20

Compare this design to those found in modern cars you will see dozens of fu=
ses.=C2=A0 Sure there are a lot more electrical items but most things have =
their own fuses.=C2=A0 This means you can size the fuse more appropriately =
for the wire used to power that device.=C2=A0 Also the connectors used are =
water tight and don't corrode as quickly.=C2=A0 Also, they are, on the whol=
e, 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.
=20
Dave=20

=20
=20
-----Original Message-----
From: bill beecher <notakitcar@yahoo.com>
To: Tom Householder <trhouse@columbus.rr.com>
Cc: Triumphs@Autox.team.net daily digest <triumphs@autox.team.net>; FOT Lis=
t <fot@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.=
=C2=A0 I should think, given the right set of weaknesses, most any section =
could melt.=20
Bill B

Serenity Now......

On Jun 23, 2020, at 4:52 AM, Tom Householder <trhouse@columbus.rr.com> wrot=
e:

=EF=BB=BFOver the years I have experienced and seen harness melt down in th=
e looms to the tail lights .. anyone ever had an under dash melt down?

Trying to answer a question asked of me.=20

Tom=20
** triumphs@autox.team.net **

Archive: http://www.team.net/pipermail/triumphs  http://www.team.net/archiv=
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ar@yahoo.com

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e

sey@cs.com

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<div style=3D"color:black;font: 12pt Arial, Helvetica, sans-serif;">
<div> <font size=3D"3">Keep in mind that these wire harnesses, like the car=
 as a whole, was designed to a budget.&nbsp; These harnesses had three (cou=
nt 'em, 3) fuses.&nbsp; As such some items were unfused like the headlamps =
and the coil.&nbsp; And those things that are fused shared a fuse so the fu=
se had to be sized to carry the current for everything on that circuit.&nbs=
p; But the wires were sized for the particular load.&nbsp; A thinner wire w=
ill have a nigher resistance and under&nbsp; short-circuit conditions the c=
urrent can be limited to a level that will not blow the fuse but the curren=
t will cause enough heating to cause the insulation to melt.</font></div>

<div><font size=3D"3"><br>
</font></div>

<div><font size=3D"3">Another factor against us is the age of the harness.&=
nbsp; The connector contacts get corroded and will get hot under normal cir=
cumstances.&nbsp; Wire strands can fatigue and break within the insulation =
again resulting in overheating under normal use.&nbsp; The insulation gets =
stiff and cracks exposing the wires within.&nbsp; Lots of potential failure=
 modes here.&nbsp; <br>
</font></div>

<div><font size=3D"3"><br>
</font></div>

<div><font size=3D"3">Compare this design to those found in modern cars you=
 will see dozens of fuses.&nbsp; Sure there are a lot more electrical items=
 but most things have their own fuses.&nbsp; This means you can size the fu=
se more appropriately for the wire used to power that device.&nbsp; Also th=
e connectors used are water tight and don't corrode as quickly.&nbsp; Also,=
 they are, on the whole, a lot younger and therefore retain more of their o=
riginal integrety.</font></div>

<div><br>
</div>

<div><font size=3D"3">But a fresh works well enough so if you fear a melt-d=
own a new harness may be a good investment.</font><br>
</div>

<div> <br>
</div>

<div style=3D"clear:both"><font size=3D"4">Dave </font><br>
<br>
</div>

<div> <br>
</div>

<div> <br>
</div>

<div style=3D"font-family:arial,helvetica;font-size:10pt;color:black">-----=
Original Message-----<br>
From: bill beecher &lt;notakitcar@yahoo.com&gt;<br>
To: Tom Householder &lt;trhouse@columbus.rr.com&gt;<br>
Cc: Triumphs@Autox.team.net daily digest &lt;triumphs@autox.team.net&gt;; F=
OT List &lt;fot@autox.team.net&gt;<br>
Sent: Tue, Jun 23, 2020 8:52 am<br>
Subject: Re: [TR] TR2-3 electrical melt downs<br>
<br>

<div dir=3D"ltr">Have a friend with a TR6 that had a significant meltdown b=
ehind the dash.&nbsp; I should think, given the right set of weaknesses, mo=
st any section could melt. <br clear=3D"none">Bill B<br clear=3D"none"><br =
clear=3D"none">Serenity Now......<br clear=3D"none"><br clear=3D"none">On J=
un 23, 2020, at 4:52 AM, Tom Householder &lt;<a shape=3D"rect" ymailto=3D"m=
ailto:trhouse@columbus.rr.com" href=3D"mailto:trhouse@columbus.rr.com";>trho=
use@columbus.rr.com</a>&gt; wrote:<br clear=3D"none"><br clear=3D"none">=EF=
=BB=BFOver the years I have experienced and seen harness melt down in the l=
ooms to the tail lights .. anyone ever had an under dash melt down?<br clea=
r=3D"none"><br clear=3D"none">Trying to answer a question asked of me. <br =
clear=3D"none"><br clear=3D"none">Tom <br clear=3D"none">** <a shape=3D"rec=
t" ymailto=3D"mailto:triumphs@autox.team.net"; href=3D"mailto:triumphs@autox=
.team.net">triumphs@autox.team.net</a> **<br clear=3D"none"><br clear=3D"no=
ne">Donate: <a shape=3D"rect" href=3D"http://www.team.net/donate.html"; targ=
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</div>

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