At 09:56 PM 8/7/02 -0500, Bob D. wrote:
>Anything with electrical current running through it will dissipate some
>degree of heat. Rheostats can run hot, depending on their setting and how
>much power they are controlling. Fuses can get uncomfortably warm to the
>touch. Wires and connectors should never go beyond luke warm. These are just
>unscientific guidelines.
>
>Bob Donahue (Still stuck in the '50s)
>Email - bobmgtd@insightbb.com
>52 MGTD - NEMGTR #11470
Fuses and fuse holders **should** never run hot, or even warm. It
is bad design technique. Hot fuses are generally caused by cheap or dirty
fuse holders with relatively high resistance spring metal contacts, holding
the fuse body. Given the right conditions, it can cause the fuse to open or
"blow" due to the heat and not to an electrical short.
I had this happen to me in a Subaru. The dealer had installed a set
of fog lights, and connected them to the headlight fuse. The fuse would
blow after about a 1/2 hour of use. Larger fuses were installed and
continued to blow.
It was noticed that the fuse holder was very warm/hot. It was found
that the the combination of the headlights and the fog lights cause the fuse
holder/fuse combination to heat up and to melt the fuse element. It happened
no matter what size fuse was installed. A amp meter indicated that all was
well with the current draw. Just bad fuse block wiring. The solution in
this case was to have the fog lights removed from that circuit. Subaru
issued a recall for the problem later that year and changed the fuse block.
Something about melting plastic and fires... : - )
Wires are something else that ** should ** never run hot, and not
even warm. Hot wires indicate that is a problem with the circuit, or the
connections to the circuit. In our case, the MGs are a minimum of 22 years
old, and corrosion and oxidation can build up on the electrical connections
(bullet connectors). This can cause wires and connectors to get hot
especially with high current loads such as headlights and such. The solution
is to clean the connectors as you run across them, or if something indicates
that there is a problem with a circuit like dull or dim headlights. Also,
don't forget the ground connections. They can be a source of major problems.
Gene Balinski
80 B
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