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Re: alfa-digest V8 #995



Well, 350/12 = 29 > 20, so your fuse is too weak for sure. If your wires really aren't getting hot you might get away with pulling 29 amps through that circuit, but I generally don't pull more than 20 through 12 gauge wire. If you replace the battery-->relay wire with 10 gauge, you should be fine for 30A. The most that any of the wires going to the individual headlights have to carry is 8.3A, which is no problem for 14 gauge wire or bigger. The other thing that springs to mind is that H1 bulbs are polarized--the nickel pin is the ground--if you get that backwards, it will blow your fuse w/in a minute regardless of proper wiring.

--On Tuesday, August 6, 2002 5:38 AM +0000 alfa-digest <[email protected]> wrote:


Date: Mon, 5 Aug 2002 21:27:04 -0700
From: "Tony Sims" <[email protected]>
Subject: She cannah take tha' mooch pawr-r-r, Cahptain!

Dear Ampy,
Following to a recent bout of stupidity, I had cause to re-wire the
headlights on my car.  Since the original configuration did not provide a
relay for the low beam circuit, I added one, of 40 amp capacity, and I
replaced the original high-beam relay with a new 40 amp one as well.
Again, since the original configuration did not provide fuses for the
high- or low-beam circuits, I added a 20 amp fuse to each circuit
upstream of the relays.  All the power delivery wires from the battery to
the relays and on to the high- and low-beam headlights are 12 guage wire,
and a dedicated ground circuit was created with the same 12 guage wire.

Because I did not want auxiliary lamps, I chose to install bulbs of higher
than original wattage to provide improved illumination.  The main beam
bulbs are H4, 65w low/75w high.  The high-beam bulbs are H1, 100 watt.
Everything seems to work swimmingly, and the system generates an
impressive amount of light.  It also consistently blows the high-beam
circuit fuse after about 60 seconds.

I double checked the path of all my wires to make sure nothing is
shorting, and double checked all my connections to make sure they are
correct.  It all looks good.  None of the wires are getting hot, nor are
the relays.

The answer would seem to be that I have far too much wattage
(75+75+100+100 = 350) running through my high-beam circuit for a 20 amp
fuse.  Not being of the electrical-engineer persuasion, what I do not
know is what to do next.  Could I safely increase the capacity of the
high-beam fuse to 25 or 30 amps?  Or must I reduce the draw by installing
lower-wattage bulbs?  I am assuming that other than the fuse, my circuit
is of great enough capacity, but as previously stated, this isn't my area
of expertise.

Dear Ampy, please help me!

Dimbulb
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