Peter C. described the "Why" quite well.
This is a description of my headlight wiring.
I used a heavy duty dual circuit relay from JC Whitney. It has two separate
circuits each with it's own internal fuse, one for high beams and one for
low beams.
This unit has 5 connections, 1) low beam in, 2) low beam out, 3) high beam
in, 4) high beam out, 5) battery.
a. 16ga wire from main fuse box to light switch.
b. 16ga wire from light switch to dimmer.
c. 16ga wire from dimmer switch to the relay for high beam.
d. 16ga wire from dimmer switch to the relay for low beam.
e. 10ga from battery to relay.
f. 12ga from relay to high beams.
g. 12ga from relay to low beams.
The 16ga wire from the dimmer only provided power to the relay. The relay
makes the connection between the 10ga from the battery and the output to the
lights.
You could also use two single circuit relays.
A similar setup will work for driving/fog lamps.
I hope this makes sense.
Larry Miller
http://www.ado13.com
If life was fair, Elvis would be alive and all the impersonators would be
dead.-Johnny Carson
----- Original Message -----
From: Peter C. <nosimport@mailbag.com>
To: Paul A. Dolloff, Ph.D. <pauld@ekpc.com>
Cc: <spridgets@autox.team.net>
Sent: Thursday, September 09, 1999 7:37 AM
Subject: Re: driving light and generator
> At 04:51 AM 9/9/1999 , Paul wrote:
> >Peter,
> >>I read your post with interest as I am about to install a driving and a
> >fog lamp in addition to a stereo (with an external amp). I bought a
> >couple of additional Sprite fuse blocks so that I will have six total.
> >
> >I've heard other people mention using relays. How do they help,
> >where can I get them, and how many do I need. Perhaps the List
> >would be interested in your response as well as just me.
> ----
> At Paul's request. Understand that I am not an electrical engineer, nor do
> I play one on TV.
> In simple terms (my limit) a relay is a remote switch controlled by
another
> devise (switch). They are useful in reducing the load on a switch so that
> the full draw of the consumer (lights, stereo, action) does not go thru
> the switch which would necessitate a larger and cumbersome mechanism. They
> are also used to lessen the length of wire required which allows for a
> smaller gauge of wire.
> In the old days, when I put driving lamps on my car, I ran 10 ga. wire to
> a hefty switch on the dash in order to get as much power (or less voltage
> drop) to the lights as possible. Now I can run 16ga wire using a relay and
> have the lights be switched with my headlights without adding load to the
> (flimsy) headlight switch.
> So basically, a relay can lessen voltage drop to a devise and lessen load
> on a switch and allow lighter gauge wire.
> I hope that's clear. As to specific ways of wiring lamps, etc., others on
> the list are probably better suited, and can likely clarify and enhance my
> paltry attempt to answer your questions.
> HTH Peter C.
>
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