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Thread: Master Switch Wire Guage

  1. #1
    Join Date
    Feb 2002
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    Gainesville, GA
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    Default Master Switch Wire Guage

    While I'm asking these related questions, when wiring the Master switch, do you normally increase the wire size to account for longer runs, or just use the stock size? Stock appears to be 4 AWG. Depending on location of switch, longest run would be about 5 feet each way for a total run of 10 feet. Going to 2 AWG would certainly work, but is more expensive, heavier, and harder to work with.

    My feeling is that the stock 4 AWG should be fine since the total electrical loads are going to be less than stock without power accessories, radios, turn signals and headlights (unless we do a night ECR but that is not likely).

    Again, I'd love to hear opinions and what others have done.

    Rory

  2. #2

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    Stock is fine. The only time the wire gauge comes into the equation is during starting. Wire gauge for the starter cables is sized to start the car when it is cold out and the current draw to start the car is higher than warmer temps when we typically race.
    _____________________
    Mike Taylor
    1995 MX-3 LeChump/ITX

  3. #3
    Join Date
    Jan 2010
    Location
    Houston-ish
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    932

    Default

    8awg from the alternator to the switch
    4awg from battery to switch
    4awg from switch to starter
    8awg from switch to accessories (stock fuse box)

    It was all free to me since I had piles of it from my car audio days. has worked in this car without a single hiccup for about 6 years now. car still starts just fine even in sub-freezing weather with battery in the trunk (so power cable run is 12-15ft from battery to starter.)
    Houston Region
    STU Nissan 240SX
    EProd RX7

  4. #4
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    Default

    Thanks for the info. Pretty much confirms my suspicions. Cheaper and Lighter is is. We don't get to say that very often

  5. #5
    Join Date
    Jan 2001
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    Buffalo, New York
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    Default

    I use welding cable.

  6. #6
    Join Date
    Dec 2008
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    Orlando, FL
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    Default

    ^^^ this. affordable, avaialble, and flexible makes it a good choice. Don't be affraid to have too large a wire - it's never too big (except weight and cost) but can be too small.

    another good option is Accel lightning cable, which is very flexible and light. it's Cu coated Al strands in a bundle. I run 2ga from battery - switch - starter. the lightining cable doesn't appear to be as widely available anymore though, most listings online are out of stock. maybe it's no longer being produced?

  7. #7

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    I use battery cables from E30 or E36 BMWs with trunk mounted batteries. They are $7 from Pull-a-Part. The E30 battery cable can be removed in < 5 minutes.
    _____________________
    Mike Taylor
    1995 MX-3 LeChump/ITX

  8. #8
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    Feb 2002
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    Gainesville, GA
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    Default

    Any suggestion on local sources for the welding cable? I know that a welding supply store sounds like the obvious answer, but I've checked 2 of them near me and neither had any bulk cable. I could buy a grounding cable and cannibalize it, but that proved to be pretty expensive.

    If looks like Advanced has #4 and #2 battery cables in up to 6 ft lengths with a battery terminal on one end and a ring terminal on the other end for about $16. A similiar sized "starter" cable with ring terminal on both ends for the return run is about $9. This seems like a pretty cheap alternative and kinda like the easy button. Any thoughts?

  9. #9
    Join Date
    Dec 2008
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    Orlando, FL
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    any general supply store, electric, some army surplus, etc.. shops have the cable. find a weird old bearded man with a beat up old japanese pickup in your area and ask him. or a fat sweaty guy with button up shirt. either will know the nearest stroe for such things. inch to inch you will pay a lot more for the advance cable but they do work for a quick and easy fix.

  10. #10

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    McMaster-Carr has a warehouse in Atlanta which should give you overnight ground shipping. Great place to find stuff like this. Click here to view their welding cable selection

  11. #11
    Join Date
    Jan 2010
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    Houston-ish
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    Any local farm or tractor supply will have welding cable as well. Heck, there's a grocery store (and farm supply) in Alvin, TX town that carries more metric hardware and welding supplies than all of the local auto parts and big box 'hardware' stores combined.

    I was looking for a handful of 12x 1.5mm fasteners the other day and the only place I could find them was the farm supply. Advance Auto, autozone, NAPA, Oreilly, Home Depot all gave me blank stares. crazy.
    Houston Region
    STU Nissan 240SX
    EProd RX7

  12. #12
    Join Date
    Mar 2001
    Location
    Connecticut
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    7,346

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    Quote Originally Posted by Matt93SE View Post
    Advance Auto, autozone, NAPA, Oreilly, Home Depot all gave me blank stares. crazy.
    Did they ask you for year, make, and model first?
    Not my circus...not my monkeys...

  13. #13
    Join Date
    Feb 2002
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    Gainesville, GA
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    493

    Default

    Tractor supply. Good idea.

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