Date:         Fri, 19 Dec 1997 17:41:37 -0800
Reply-To:     W Li <wli@U.WASHINGTON.EDU>
Sender:       Vanagon Mailing List <vanagon@gerry.sdsc.edu>
From:         W Li <wli@U.WASHINGTON.EDU>
Subject:      Re: aux headlights
Comments: cc: jwalker@ua1vm.ua.edu
Content-Type: TEXT/PLAIN; charset=US-ASCII

Some additional tips re aux lighting to add to Joel Walker's detailed
posting:

These lights draw a lot of electricity..........
One safe standard is to limit wire temperature to 212 degrees F. max when
in a bundle in a test atmosphere of 135 degrees F. (from the copper-wire
table in the Radio Amateur's Handbook).

        Wire size       continuous duty current limit (amperes)
        10              33 A
        12              23 A
        14              17 A
        16              13 A
        18              10 A
        20              7.5 A

Now since each 55 watt lamp draws 4.6 A, you would want to wire each lamp
up with at least 20 gauge wire..... for safety and to minimize voltage
drops, it is wiser to go up and use lower gauge (thicker) wire.

You might be tempted to wire the aux lights in by tapping into the
existing headlamp wiring... DON'T.
You risk overloading the existing relays and wires. A safer method, is to
wire relays for each system (fog, driving) by running a new wire from the
battery positive terminal to relay(s).  As Joel advises, place 8A fuses to
each lamp. What I did was run a heavy 12G wire from the positive battery
post to a separate fuse-relay box mounted in the engine compartment which
I could access easily. The current for operating relays is small (0.1A)
and can be tapped off of the low (or high) beam wire.

Take your time,... draw out a wiring diagram before you start work. Use
your ohmmeter to check for shorts before you hook up the hot leads, and
finally test the voltage at the lamp connector BEFORE you hook up your
expensive lamps.  [For myself, I use OEM Bosch 100 and 150 watt relays
scrounged from wrecking yards for $1 each, and test each one with my
ohmmeter before I install. So far, all of them have performed without
failure].

All this may sound real compulsive, but wiring mistakes are all too easy
to make, and the consequences are very bad.

Final caveat: route the wires with care, avoiding strain, and areas which
can damage the insulation through rubbing contact points. Those plastic
tie-wraps make the whole installation look professional.

Good luck!

Wei-i Li
95 EV Camper