ArthurK101@aol.com wrote:
>
> In a message dated 97-07-25 11:06:48 EDT, bnicho19@bellsouth.net (bill
> nichol) writes:
>
> > Trevor Boicey wrote:
> > >
> > > bill nichol wrote:
> > > > The cure was so simple i almost hate to admit it. I went through my
> > > > lights one by one checking restance to ground abd found each of my
> tail
> > > > lts pulling 1 to 4 Megohms (not a miss print)
>
> > >
> > > Just a note that high resistances such as this draw LOW currents.
> > >
> > > So if the resistance of the circuit is really in the megohms, the
> > > draw would be almost nothing, the lights would never light, and you'd
> > > never get any hot wiring. Essentially, nothing would happen except
> > > your battery might go dead after 4 billion years of powering the
> > > circuit.
> > >
> > > > instead of the more normal 4 or less ohms.
> > >
> > > Which will actually draw a lot of current.
> > >
> > > Of note though, filaments have very low resistances when cold, and
> > > the resistance increases when hot. This is why a light bulb seems
> > > like a dead short (ie: fuse) but doesn't draw infinite current.
> > >
> > > You can use resistance to test whether filaments are intact, but
> > > you can't really speculate on the current draw of them when
> > > running.
> > >
> > > --
> > > Trevor Boicey
> > > Ottawa, Canada
> > > tboicey@brit.ca
> > > http://www.brit.ca/~tboicey/
>
> > Trevor,
> > You went to a whole different school of electrical theory than the
>rest
> > of the world. The high restance was not through the bulb(duh!) The high
> > restance was because the fantastically poor ground points and
> > terminations used by Lucas, allowing incredible amounts of corrosion to
> > accumulate. Even promoting in some instances through dissimiliar metal
> > corrosion. Corrosion causes restiance. resistance causes heat. If
> > voltage is constant then current must increase to carry the increased
> > load.
> > If you still feel compelled to disagree, fine. But, please don't try
>to
> > discount the FACT that removing the corrosion ended my fuse problems.
> >
> > All hail the prince of Darkness!
> > Bill
> > 78Spit
> > 80Wedge
> >
>
> Bill, now, now! Trevor is right. In the total circuit -- I=E/R (I is
> current, E= elctromotive force or voltage, and R=resistance) - so if E is
> constant and R increases then I goes down. It can't go up ( an example
> would be an open circuit - where the resistance is infinite and no current
> flows). High resisrance means that the filiaments of the bulbs would not have
> much current flowing through them and would not heat up. Which means they
> would not "light" up. As for the blowing of fuses - increased resistance
> would not cause that. Fuses blow when current increases beyond the rating of
> the fuse. That's why fuses are rated in amps (the measurement for current).
>
>
> Your statement " If voltage is constant then current must increase to carry
> the increased load" is not true. Look at the formulae E=IR, I=E/R, R=E/I.
> Anyway you slice it, if E is constant and R increases, I MUST decrease.
>
> SO since constant voltage with increased resistance causes current to
> decrease, the blown fuses were caused by something other than the increased
> resistance (maybe a "short" in the wires or to ground somewhere else in the
> circuit).
>
> To be nice about this, and my mother always said to be nice, I think the
> confusion may be partly a result of Trevor's throwing in a discussion of the
> filiament resistance. The filiament resistance increase to which he referred
> is after heating (which would not take place if the current in the circuit
> were too low, which is what very high resistance would cause - as in your
> case). Hence you would get a dim bulb but not a blown fuse.
>
> I didn't read him as saying that the filiament resistance had any bearing in
> your case. He appears to have thrown that in as an aside. But his comment
> (in a later e-mail) that the increased resistance was not causing blown fuses
> is correct. Something else cured your blown fuse problem. The fact that you
> cleaned up the connections had nothing to do with that problem.
>
> Please check out exactly what you both said and I think you'll find some
> agreement.
> BTW the "duh" comment might reqiure a little eating of crow on your part. :-)
> Cheers.
>
> Art Kelly
Art,
Trev and I have pretty much worked this topic to death and yes my
recolection of ohms law was pretty foggy. Never the less all the
fumbling around and cleaning of corrosion( which needed to be done
anyway) did have the desired result. I haven't blown a fuse in several
thousand miles.
Fixed by dumb luck? who cares it's fixed and it stayed fixed.
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