Re: Using relays w/ euro lights

[shields@tembel.org (Michael Shields)]

> My  Euro lights are in (stock 55/60w w/ 60w inners for now)
> my 1983 UrQ but now for the wiring. I followed the thread a
> couple of months ago regarding wiring relays but I just
> wanted to ask a couple of questions. Should I use 3 relays, 1
> for lows, one for outer highs, one for innner highs?

You will need to decide that based on the relays you are using.  The
basic formulas are P=EI -- watts equals volts times amps; and
according to the NEC you don't want continuous load over 80% of
nominal capacity.  Pretend you only have 12V at the headlights and
you'll have a little extra room beyond that.  A 30A relay will handle
two 130W bulbs with no trouble.

I skipped over all the automotive shops and bought all the crimps and
relays and fuses from Digi-Key (http://www.digikey.com); they have the
quality stuff.

> I know the
> switched power should come straight from the alternator but
> should the grounds for the lights be new heavy gauge as
> well?

Yes!  Remember it is a *circuit* and the current path is equally
important in both directions.

> If not, I know I need a new set of grounds,  which one
> gets the new grounds, the relays or the lights? Thanks a lot.

The relays also need a ground, but it is just for signal and draws
only a small amount of current.  Use light-gauge wire from the switch
to the relay and the relay to the ground, and use heavy-gauge wire
from the alternator to relay, relay to bulb, and bulb to ground.

Read up on household electrical wiring if you're unsure about current
capacity; it's all the same physics.
-- 
Shields.