'81 tic-tac

and I must say it made a difference! Bought $30 worth of parts from the local electric-parts-heaven-for-nerds-store today. And that was only because I had to buy 50ft of 14awg cable. Stupid crap cost me $10 and i have about 40ft left over :P

the wiring was relatively simple to do if you know how to follow a schematic and can crimp and solder.

I went from this:
<img src="http://dsl.torque.net/images/norelaycircuit.gif">
to this:
<img src="http://dsl.torque.net/images/relaycircuit.gif">

The wiring is ghetto-fab for now however since i put it all together and wanted to make sure it worked before I made it look pretty. So as she sits right now there are gobs of red and black cable littering the front of the engine bay. Oh well, gotta get some heat-wrap and seal it all tomorrow.

maybe i'll get a schnazzy pic of the finished product when it's done and pretty

Anyone know how high a wattage bulb I can use now with 14awg cable all around and 20amp fuses?

- GT Style -

<center><img src="http://pictureposter.audiworld.com/46543/h1-h4_partial_harness.jpg"></center><p>It's only partially finished in this pic as the H4 plug's &amp; power supply weren't attached yet and the harness wasn't finished being "wraped".

What amperage relay are U running? If you have 30 amp relays, then 20 amp fuses are good as it's cheaper to replace a fuse.

I used white &amp; yellow to watch the factory colors. I also used dual 87 pole realys (instead of the common 87a/87) so that I could have all low beam off 1 relay &amp; each L&amp;R high beam off it's own relay.

Also, you may want to take the power from the battery instead. Say your fan kicks on &amp; the alternator decides to increase output, you don't want that surge going into the lights.

icon73

My relayed turbo euro headlights get power directly from the battery now, easy, since I jumped the power from the jump post located in the engine bay.

hals86cgt

Remeber Wattage (power) is calc'd by Volts x Amps (in a DC circuit) so your max watts assuming a 20A fuse/breaker is 12-14V x 20 = 240-280W depending on your actual voltage.

As for cable capacity, it depends on several factors, 1.) the length of the cable run from the + source back to the ground, 2.) The alloable voltage drop which depends on what equipment is being powered. Lites are pretty tolerating of low voltage thus a 10% drop is normally allowed(unlike radar units) and 3.) Cable insulation temperature rating.

I ran a quick calc, come up with that your 14AWG cable is fine for the 20A load assuming the run back &amp; forth is 14' or less. As for ampacity (cable's amperage carrying capacity) of your cable, it depends on the cable's insulation rating, the minumum rating for 20A capacity using 14AWG in a heated engine space is 80deg C 176degF.

The insulation rating info should be on the cable.

You may be able to go up to a 25A fuse and still be OK depending on the cable insulation.

Sorry for the long technogeek reply, but since you asked....

Hal in Annapolis

'81 tic-tac

I'm using 30 amp relays. I do have the 87/87a relays, however the low beam and high beam each have their own relay, the 87a simply isn't being used.

I would have liked to use yellow and white to stick with factory colors, but I opted to go the cheap route and bought a 50ft spool of red/black.

I still need to go out and get some heat-wrap today

I am actually running my harness from the battery+ however, the battery+ and alternator+ share identical potentials, so I believe whatever surge there could be would be the same from either terminal. It was infact easier to run it from the battery+ though.

I'll try to get some pics after I wrap it

'81 tic-tac

Thanks a bunch! As I was reading, some of the calculations came back to memory from some of the college classes I took. The heat rating is very interesting though, I'll have to take a look at the wire today and see what it's rated at.

Really appreciate it!

hals86cgt

No Problem, i was avoiding doing other work..&gt;LOL

Hal in Annapolis