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Re: Is a relay needed in a fog light installation

To: "mgs" <>, "Barrie Robinson" <>
Subject: Re: Is a relay needed in a fog light installation
From: "Telewest \(PH\)" <>
Date: Mon, 30 Dec 2002 17:24:48 -0000
The point about relays for auxiliary lights, front and rear, is that they
are usually used with the main lighting and go off with the main lights.
Without relays the existing switches and wiring have to cope with the
additional load of the auxiliary lights as well as the main lights, and
after 30 years they are not really up to it, at best you lose some voltage
along the way and at worst it can melt the switch.  Relays allow full power
to be delivered to the lights without a heavy current having to travel
through thinner wiring and older switches, which is why it is also a good
idea to use relays when updrading the headlights to higher power units.

----- Original Message -----
From: "Barrie Robinson" <>
To: "Telewest (PH)" <>; "Bullwinkle"
<>; "mgs" <>
Sent: Monday, December 30, 2002 6:44 PM
Subject: Re: Is a relay needed in a fog light installation

> Paul,
> It would seem that the only advantage of using relays would be the saving
> of heavy duty switches and a few feet of heavy duty wire.  Perhaps then It
> would be economically sound to use heavy duty switches and wire instead of
> relays and its wiring.  After all we are only talking about saving heavy
> duty wire between relays and dash - in my case just a couple feet.  The
> arcing would be done in the switch instead of the relay but this is just
> the same as arcing in the relay.  The fire risk would be no more than
> normal provided the usual electrical wiring standards are used.  (This
> would not apply to the heavy draw of the starter where we get into biggish
> amps).  The whole subject is confusing as obviously the car manufacturers
> would use the most economic (not necessarily the safest) way of wiring up
> vehicle.  This tends to suggest that relays have a great advantage but for
> the life of me I cannot see what it is - except for the starter of course.
> At 09:25 AM 12/30/2002 +0000, Telewest \(PH\) wrote:
> >It certainly has, that is exactly what a relay will do!  You use the
> >original circuitry to power the relay, which only takes milli-amps, via
> >auxiliary light switch and connect one side of the relay contact back to
> >heavy gauge brown like at the fusebox or even the solenoid, via a fuse,
> >other side to the lamps, of course.
> >
> >----- Original Message -----
> >From: "Barrie Robinson" <>
> >To: "Bullwinkle" <>; "mgs" <>
> >Sent: Sunday, December 29, 2002 7:44 PM
> >Subject: Re: Is a relay needed in a fog light installation
> >
> >
> > > Christmas cheer has dulled my senses - but surely a relay will not
> > > compensate for wiring intended for only one lamp
> Regards
> Barrie
> Barrie Robinson -

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