Date: Sun, 6 Oct 2002 12:48:14 -0600
Reply-To: Ben McCafferty <ben@KBMC.NET>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Ben McCafferty <ben@KBMC.NET>
Subject: Me too: Re: [Syncro] Sanity Check - Wire gauge for wiring SA
headlights
In-Reply-To: <OE21NZxS6VqRACPMZuO0000a9b6@hotmail.com>
Content-Type: text/plain; charset="US-ASCII"
While we're on the subject:
90 westy syncro. I relayed my headlights a couple of weeks back. I didn't
change the factory harness to the bulbs.
Before leaving for ABQ, I put in 80/100W bulbs in the outer lights, and 100W
bulbs in the inner driving lights. When night fell, I had no low beams. On
checking, the fuses (10A) for the low beams were both burned, and the fuses
for the high beams/driving lights (10A per side) were intact. Both the high
beams and the driving lights worked fine. I had some 15A fuses in the
glovebox, so put in two of those for the lows until I got where I was going.
The high beam fuses never burned.
A few questions:
1--Do I assume correctly that the highs and the driving lights are on the
same fuse (i.e. one fuse for left, one for right)?
2--If so, why did my fuses for the lows burn, but the highs didn't?
3--What gauge wire do I need (as per Brent's message below) to handle the
load?
All I can think is that the wire to the lows is a smaller wire (higher
gauge) and overloaded, while the wire to the highs is bigger.
Any thoughts would be greatly appreciated. Incidentally, the 80W lows
hardly look different than the 55W lows, which also leads me to think the
wire is too small.
tx,
bmc :)
"Faith will move mountains, but you'd better bring a shovel...."
From: "Brent Christensen" <sbsyncro@hotmail.com>
Date: Fri, 4 Oct 2002 17:22:24 -0700
To: <Syncro@yahoogroups.com>, <vanagon@gerry.vanagon.com>
Subject: [Syncro] Sanity Check - Wire gauge for wiring SA headlights
I am planning out the wiring for my new e-code headlights, and I wanted to
run a sanity check for the gauge wires I plan to use.
I will be running 100/80 H4 bulbs plus the 55w driving lights. I will be
using relays to hook everything up, of course!
Total Amperage draw:
High beams ~8.5 amps x 2
Low beams ~6.7 amps x 2
Driving lights ~ 4.6 amps x 2
Based on the wiring tables I can find, 14 awg wire is duty rated to 17 amps
for stranded wire at up to 135 degrees ambient temperature. Since the lamps
will each be wired separately from the relays, I am assuming that I can use
the following wire gauges:
8 awg as a "feed" from the battery to the fuse block.
10 awg from the fuse block to the relays
14 awg from each relay terminal to the individual lamps.
Can anyone more expert than me confirm or dispute my findings? It tends to
support the wimpy 14 awg wiring that VW uses from the factory. By the way,
at 8.5 amps current draw, the voltage drop from 12.5 volts through six feet
of wire are as follows:
10 - 5.2% (or 11.9 volts)
12 - 8.3% (or 11.5 volts)
14 - 13.1% (or 10.9 volts)
Maybe this is a bigger reason to use 10 awg wire to the brights and low
beams than the actual rating of the wire...?
Brent Christensen
Santa Barbara, CA
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