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RE: Race car wiring

To: land-speed@autox.team.net
Subject: RE: Race car wiring
From: "Albaugh, Neil" <albaugh_neil@ti.com>
Date: Mon, 9 Jun 2003 11:08:25 -0500
List;

I'll second Dave's suggestions and add a few of my own.

One of the most common causes of failures in military electronics systems is
connectors. Assembling them properly is vital but if you can eliminate a
connector, so much the better. If it isn't there, it can't fail. Ask
yourself if a connector is really needed in a particular place; anything
that would need to be changed in a hurry or disassembled on-site would need
a connector.

When you are wiring a car, use hefty gauge copper-- you don't want to
generate much of a voltage drop in the wiring. I'd suggest that you try to
find some surplus MIL-SPEC wire. eBay is one source for it and other surplus
houses sometimes carry it. The difference between it and the stuff you find
at Checker Auto, etc., is that the mil aircraft stuff has a tough, high-temp
insulation rather than just PVC and its conductors are made up of many, many
strands of fine-gauge high-purity copper (often silver-plated, too!) rather
than just a few strands of larger copper. This gives the mil wire much
better flexibility and ability to withstand vibration. Any type of wire
should be supported and routed away from heat sources, though.

Switches are another source of problems. Use switches that are rated for DC
service. The voltage and current ratings are printed on the switch. It will
say something like "10A 250VAC, 5A 28VDC"; this means that the switch
contacts will handle up to 10 amps in an AC application but only 5 amps in a
DC application (like automotive). ...and no, if the switch is operated on
less than 28V DC, it can't be used at higher than its 5A rating. Switch
contacts are made of various alloys-- some are not suitable for DC and if
you don't find a DC rating on the switch, don't put it in your car-- use it
somewhere else at home. Inrush current is very high for loads such as lamps
(brake lights, etc) and motors (electric fuel pumps, etc) so the switch and
wiring needs to be able to handle this high peak current.

I's suggest laying out a rough drawing of your electrical components and
then making up a wiring diagram. Watch those ground connections-- the
current's gotta go back to the battery somehow.

Regards, Neil     Tucson, AZ

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