On 10/25/05, Robert Cardo <rrecardo@webtv.net> wrote:
>
> <<<In regard to installing optional higher wattage lamps, isn't the
> purpose of the relay to remove the headlight current from the headlight
> switch?>>>
>
> Headlamp amperage draw would be a better analogy.

Current is measured in amperes (amps). "Amperage" is basically just another
way of saying "current".

<<Is the stock wiring harness sized for 20-amps of current draw?>>
>
> Sure.
> Each operation of the lamp circuit is fused individully, so if there
> was an overload the fuse would fry before the wire.

The 1.5mm2 wire the headlights run on is rated for 16 amps.

<< Can you safely install higher amperage fuses in the headlight
> circuits without melting down the wiring, fuse block or bulb
> connector?>>
>
> Yes.

Heh. Depending on your definition of "safely". A pair of 100w high beams on
each side will drain about 16A down that single 1.5mm ground wire into that
shared spade connector under the dash. That's safe enough, assuming the
connections are all clean. Of course a chafed or nicked wire causing a minor
short could add a few more amps current draw. Fuses should always have the
weakest rating of anything on the circuit. You could put a higher amperage
fuse in, or cram a bit of 20ga solid wire in its place, but that kind of
defeats the purpose of the fuse. The odds of a situation arising which
causes 19.5A draw on the circuit and damaging that 16A rated wire are a
definite longshot, but those odds drop to near zero if you use an
appropriately rated fuse. I'd recommend putting no more than a 15A fuse on a
1.5mm wire, myself.

Personally, I ran a 10ga wire separately for each circuit, 10A circuit
breaker on each, fed by four 30A relays, with a DPDT relay "bypass" on the
breaker panel in case of relay failure for whatever reason. Ground wire is a
single 8ga running back to the battery, dash, and engine compartment.
Excessive capacity, over protected.

--
John Bange
'90 Vanagon
"We'd tell a monkey how to peel a banana, if he said he was peeling one in a
Vanagon."