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Cable ferrule conductivity question

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Comments

  • #32
    [Deleted User]
    Posts: 5,238 ✭✭✭ [Deleted User]


    Yurp, the owner sank it for a week.
    I ran for the hills, one of those cheaper buy a new boat jobs.


  • #33
    hesker
    Registered Users Posts: 1,490 ✭✭✭hesker


    Was reading up about another aspect of ferrules when I found this pdf below. Thank God the lockdown restrictions are easing as I clearly need to get out of the house.

    I think it supports what I said earlier about oxidation.

    https://tinyurl.com/hud38sy3

    In summary a properly applied ferrule breaks through the oxidised copper and provides a connection with superior conductivity vs bare copper cable.


  • #34
    [Deleted User]
    Posts: 5,238 ✭✭✭ [Deleted User]


    As soon as you drive a screw terminal into the ferrule it'll etch away the tin on the contact area more than likely while preserving the rest that's exposed to the environment.

    Don't get me wrong I support nerd behaviour...I have on occasion ferruled my crimps..ahem..for CSA mechanical robustness reasons...

    I generally think you learn more on the tools and verifying empirical results than theorising...

    When you're dealing with big cables and lugs a crimper is effectively compressively welding the copper together..it's a no-brainer that it's better.


  • #35
    hesker
    Registered Users Posts: 1,490 ✭✭✭hesker


    Sir Liamalot wrote: »

    I generally think you learn more on the tools and verifying empirical results than theorising...

    They both have their place in learning but it’s in the practical application of something that you usually really understand the basis of theory.


  • #36
    [Deleted User]
    Posts: 5,238 ✭✭✭ [Deleted User]


    Agreed although I usually find it as a reference for how much I was lied to by marketing and advertising and ascertain the percentage derating I have to apply to the device I was building.

    The difference between pdf sell sheet performance and actual real-world performance in the off grid industry is a shockin' disgrace.

    Just for context after 2 years testing I have yet to see li-ion beat lead-acid at anything but energy density.
    In fact Li-ion is performing way worse when you factor the efficiency losses associated with thermal management and the cost per kWh.


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  • #37
    10-10-20
    Registered Users Posts: 6,646 ✭✭✭10-10-20


    Tin is the sacrificial coating, it's more reactive than the underlying metal, but also much weaker as it's a soft metal.

    Tin makes its own problems too. It has a very nasty habit of creating hair-like growths called "tin whiskers" when used in power equipment and for that reason is no longer used in a lot of IT equipment (such as rack power distribution units).
    https://nepp.nasa.gov/whisker/background/index.htm
    https://nepp.nasa.gov/whisker/anecdote/af114-transistor/index.html

    The growths are often attracted to the opposite pole and will grow until they reach the flashover distance, short and cause an arc/plasma path and completely vaporise. You'll be a while root-causing those ghosts if a breaker drops!


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