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Discussion Starter #1
What is the amp rating on a brake peddle light switch? Do you think I can run the brake lights straight through the oem switch without a relay?

Also I could not find this in the knowledge base, what is the ratings on automotive wire. As in 8 gauge is good for?
10 gauge is good for?
12 gauge is good for? and so on.
 

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Doc here, :pimp:

If you are running Stock lighting, and a stock switch, and a relay was never required, then it should not be an issue now..

If you are modifying that is a different story..AND running the Brakelamps direct from the switch will NET you no turnsignal operation..as they are supposed to be wired through the Turnsignal switch for Isolation.

As for the Wire gauge chart..

you need to do a search for a national AWG chart..You need to know the following of your system:
  • The length of the run of the wire.
  • The Composition of the wire (what alloy's)
  • Is the wire solid or stranded (most Vehicle apps are stranded)
then draw a line between the two sides of the chart, for the length and type wire, it will give you the ampacity..

Doc :pimp:
 

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Discussion Starter #3
I noticed that the wire that runs from the front to the rear of the car into the trunk for the brake lights reverse lights and so on are a different material. I would assume aluminum. Do you know why that is? '85 g-body
 

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Doc here, :pimp:

If it's a flat ribbon cable, it's probably aluminum..and they probably did that for corrosion Control..

THE bad news is it won't solder..and it does not crimp well and breaks real easy.

Doc :pimp:
 

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Discussion Starter #5 (Edited)
MAYBE SOMETHING FOR THE KNOWLEDGE BASE

Automotive Electrical Wire Information

To select the correct gauge , first determine the amperage the circuit will carry. then measure length of wire in circuit including return ground wire. Find nearest amperage value in chart 2 and read across to appropriate length column. This is correct gauge. For 6 volt systems use a wire 2 sizes larger then required for a 12 volt system.

Chart 1

Typical Amperage per Circuit
Electrical Circuit Amps
Air-Conditioner 13-30
Back Up Lights 3-4
CB Radio 2-4
Clock 0.3
Dome Light 1
Electric Defogger 20-25
Headlight ( Low Beam) 8-9
Headlight ( High Beam ) 13-15
Headlight Dimmer ( Automatic ) 2
Heater 6-30
Horns 20
Ignition ( With Points) 1.5-4
Instrument Gauges 0.7-1
Instrument Lights 1.5-3
License Lights 0.5
Lighter 12
Parking Light 1.5
Power Antenna 6-10
Power Door Locks 3-5
Power Seat 25-30
Power Windows 20-25
Radio 2-4
Side Marker Light 1-3
Starter 100-300
Starter Solenoid 10-12
Stop Light 3.5-4
Tail Light 0.5
Trunk Light 0.5
Windshield Wiper 3-6
Recommended Wire Gauge by Application
Electrical Circuit 6 Volt 12 Volt
Air Cond. Relay to Blower Motor - 10
Air Cond. Relay to Clutch - 14
Ammeter to Fuse Block 10 12
Ammeter to Switch 12 14
Back Up Lights 16 18
Battery to air Cond. - 14
Battery to Ammeter 10 12
Battery to Fender Ground 123 14
Cigar Lighter 12 14
Coil Wire ( Low Tension) 14 16
Dome Light 14 16
Directional Signals 14 16
Fuel Gauge 16 18
Generator/Alternator to Regulator 14 16
Generator/Alternator to Start Relay 10 12
Head Light Circuit 14 16
Head Light Relay 10 12
Heater to Fuse Block 14 16
Horn Button Circuit 14 16
Horn Relay and Battery 10 12
Ignition Switch Feed 10 12
Instrument Lamps/Sending Units 16 18
Interior Lights 16 18
Light Switch to Relay or Fuse 12 14
Marker ( Fender ) Lights 16 18
Parking Lights 16 18
Radio to Ammeter or Fuse 16 18
Tail Lights 16 18
Stop Lights 16 18
Windshield Wiper and Washer 14 16


Chart 2
Amps 3' 5' 7' 10' 15' 20' 25' 30' 40' 50' 60' 70' 75' 80' 90'
1 - 18 18 18 18 18 18 18 18 18 18 18 18 18 18 18
1.5 - 18 18 18 18 18 18 18 18 18 18 18 18 18 18 18
2 - 18 18 18 18 18 18 18 18 18 18 18 18 16 16 16
3 - 18 18 18 18 18 18 18 18 18 18 16 16 14 14 14
4 - 18 18 18 18 18 18 18 18 16 16 14 14 12 12 12
5 - 18 18 18 18 18 18 18 18 16 14 14 14 12 12 12
6 - 18 18 18 18 18 18 16 16 16 14 14 12 12 12 12
7 - 18 18 18 18 18 18 16 16 14 14 12 12 10 10 10
8 - 18 18 18 18 18 16 16 16 14 12 12 12 10 10 10
10 - 18 18 18 18 16 16 14 12 12 10 10 10 10 10 10
11 - 18 18 18 18 16 16 14 14 12 12 10 10 10
12 - 18 18 18 18 16 16 14 14 12 10 10 10 10
15 - 18 18 18 18 14 14 12 12 10 10 10
18 - 18 18 16 16 14 14 12 12 10 10
20 - 18 18 16 16 14 12 10 10 10 10
22 - 18 18 16 14 12 12 10 10 10
24 - 18 18 16 14 12 12 10 10 10
30 - 18 16 14 12 10 10 10 10
36 - 16 14 14 12 10 10 10 10
40 - 16 14 12 12 10 10
50 - 16 14 12 10 10
100 - 12 12 10 10
150 - 10 10
200 - 10

( Based on a maximum voltage drop of 10% )

Marine Engine compartment conditions require additional protection. Do not exceed current load shown in chart below.

Wire Conductor Size 18 16 14 12 10
Max. Amp.
Carried
5.8 8.7 11.6 14.5 23.2 Inside Marine Engine Compartment
10 15 20 25 40 Outside Marine Engine Compartment

*Information obtained from sources deemed reliable.
 
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