In a message dated 98-10-05 19:06:22 EDT, cak@dimebank.com writes:
> While you're at it, I *highly* recommend that you put a relay on the
> original headlamps. Fuse, too. I've seen too many melted harnesses from
> cars that got a short somewhere in the lamp circuits.
Chris,
While I agree wholeheartedly, 100%, with you on everything else you wrote, I
must disagree with you on your last statement about a fuse in the headlight
circuit. Use a circuit breaker, or a fusible link, but please don't use a
fuse. If you must use a fuse, use one on each side, and then check your lights
VERY regularly.
A fuse is a very fast acting device when exposed to a short circuit, even a
slow-blow type. A momentary short in the headlight wiring, resulting in wiring
bouncing around from an encounter with a pothole, for example, will blow the
fuse, leaving you with no lights. Normally, a short of this type will cause no
real damage, as it is very short in duration, too short to burn out the wires.
A complete loss of lights, during some spirited high speed driving on winding
back roads on a moonless, cloudy night, can be fatal. At least two people on
this list have reported running off the road from just such an occurance.
Obviously, they survived, but had the events occured on a dark night, it may
well have been otherwise.
Yes, without a fuse, you can have a meltdown, but I think that is still
preferable to meeting an old oak tree along side the road head on at 60!
The best thing to do is to make sure that your wiring is in good condition,
and properly routed and supported such that a short never occurs. The
probability of a melt down resulting from a short is less than the probability
of an unplanned off road excursion. It's very unlikely that you will get a
dead short in your wiring without having first had intermitant shorts as a
warning
Fusing each side will help reduce the odds considerably, but if the one light
that's still good is the one that shorts and blows the fuse, the one that is
burned out will not help. Therefore, it is absolutley mandatory that you check
your headlights on a regular basis if you want to fuse each side individually.
Of course, if you get a dead short, it doesn't matter what you have, you will
lose the lights - A good reason to use individual wires for each side, routed
away from each other.
I posted a note to the list earlier today, describing the fog/driving light
circuit pretty much as you have, and offered to make a schematic and
connection diagram for it, transmitted as a JPG file, but for some reason it
hasn't shown up yet. If it doesn't show up soon, I will repost it.
Circuit breakers are good, but it can be hard to mount them where they don't
look out of place. Fusible links can be nearly invisible if located properly.
For those not familiar with fusible links, the are nothing more than very
short pieces of wire, 2 sizes smaller than the wire they are protecting, and
covered with a special insulation that won't melt off or burn. The wire, being
smaller than the main wire, will burn in two before the main wire if a short
should occur. It takes a while for it to happen though, so you won't be left
without lights from a momentary short.
Dan Masters,
Alcoa, TN
'71 TR6---------3000mile/year driver, fully restored
'71 TR6---------undergoing full restoration and Ford 5.0 V8 insertion - see:
http://www.sky.net/~boballen/mg/Masters/index.html
'74 MGBGT---3000mile/year driver, original condition - slated for a V8 soon
'68 MGBGT---organ donor for the '74
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