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Automotive wire size

Discussion in 'Electronic Repair' started by Chris Adams, May 30, 2004.

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  1. Chris Adams

    Chris Adams Guest

    Hello,
    I have a '91 Toyota Corolla. I have recently replaced the wires on
    the licence plate lights (in the back). The original wires
    don't have any size markings, they could be either #18 or #20.
    I used #20 wire as replacement.
    My question is: if the original size is #18, is it ok to use
    #20 as its replacement? The lightbulbs are 12V mini lightbulb.

    Thanks!
     
  2. maxfoo

    maxfoo Guest


    does the bulb draw more than 11 amps???

    Load Carrying Capacities (see table below)

    http://www.powerstream.com/Wire_Size.htm















    Remove "HeadFromButt", before replying by email.
     
  3. James Sweet

    James Sweet Guest

    That doesn't really apply to automotive, for an 11A load you'd want at least
    #14, but #12 would be better depending on the length of the run. At 12v the
    voltage drop over the wire becomes much more important.

    If the bulbs are bright enough then your #20 will be fine, I would guess
    they don't even draw an amp between them.
     
  4. Very correct, it doesn't. A lot of people -- including some of the
    beancounters at some of the automakers -- use tables like this to figure
    out "acceptable" wire sizes, with yucky results.
    They're 3, 4 or 5w items, so a max of 10w at 12v, so yeah, less than an
    amp max. That said, #20 is generally NOT used in automotive service for
    mechanical-weakness reasons. #18 is regarded as the minimum acceptable
    gauge, even where #20 would be electrically acceptable.

    -Stern
     
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