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Thread: Tin plated copper ground bus

  1. #1
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    Tin plated copper ground bus

    we mount a tin plated copper ground bus bar in our electrical enclosures for customer connections. The bus bar is tin plated but process requires tin plating to be performed before holes are punched. But what if the bus bar is plated after holes are punched in? Obviously tin is not as conductive as copper (almost 10 times the resistivity); will that make the ground bus not usable? We have received a batch of these and this is the case.

    Thanks,
    "Because it's there!"
    George Mallory

  2. #2
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    As far as I know the answer would be, no. Tin plated copper is very common and even at ten times the resistance it's still got to be conductive enough to do the job.
    Once in a while you get shown the light
    In the strangest of places if you look at it right. Robert Hunter

  3. #3
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    The plating thickness is so small you would not see a difference. The tin plating prevents copper oxide from forming which has very high resistance.

  4. #4
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    The holes are not really part of the conductive path. The surface of the bar, the contact area, is always tinplated regardless of the timing of the hole punching isn't it?
    Just because you can, doesn't mean you should.

  5. #5
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    Quote Originally Posted by jim dungar View Post
    The holes are not really part of the conductive path. The surface of the bar, the contact area, is always tinplated regardless of the timing of the hole punching isn't it?
    I understand that tin does not really affect the overall conductivity of bus bar but if bus bar is entirely covered in tin does not that make it difficult for the ground cable lug to make good electrical connection with bus bar? Wouldn't tin act as an insulator?
    "Because it's there!"
    George Mallory

  6. #6
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    Quote Originally Posted by LMAO View Post
    I understand that tin does not really affect the overall conductivity of bus bar but if bus bar is entirely covered in tin does not that make it difficult for the ground cable lug to make good electrical connection with bus bar? Wouldn't tin act as an insulator?
    Even if it has a bulk resistivity ten times that of copper, as already stated the resistance of a thin tin layer between the lug and the bus bar will not make any significant difference. Instead the greater contact area (given that tiny irregularities get crushed out) and the more reliable contact (no insulating oxide layer that has to be broken down by a voltage difference) more than make up for the increase.

    An insulator has resistivity quadrillions (1012) of times greater than a conductor.

    From https://www.quora.com/Whats-the-diff...d-an-insulator

    Examples:

    Graphene resitivity = 1.0x10^-8 best conductor

    Silver 1.59x10^-8 best common metal but very expensive

    Copper 1.686x10^-8 most popular electrical conductor relatively cheap

    Alum 2.82x10^-8 half as good as silver

    Iron 1x10^-7 you think of it as a conductor, but not used much as a primary conductor in circuits; conducts 1/6th as well as copper

    ...

    Sea water 2x10^-1 if asked most people would say this is a conductor, but its 10 million times less conductive than copper.

    Dry Wood 1.3x10^14 you might consider a good insulator a thousand billion billion times less conductive than copper.

    Teflon 1x10^23 one of the best insulators, a billion times better than wood.
    Last edited by GoldDigger; 04-21-17 at 04:31 PM.

  7. #7
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    Is this tin plating or silver plating? I've silver plated a ton of bus bars and terminal lugs in the field with a plating kit but, never tin.

  8. #8
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    Quote Originally Posted by Bugman1400 View Post
    Is this tin plating or silver plating? I've silver plated a ton of bus bars and terminal lugs in the field with a plating kit but, never tin.
    I don't think you can do them in the field but you can buy them that way
    Bob

  9. #9
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    Never mind.
    Cheers and Stay Safe,

    Marky the Sparky

  10. #10
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    Quote Originally Posted by LMAO View Post
    I understand that tin does not really affect the overall conductivity of bus bar but if bus bar is entirely covered in tin does not that make it difficult for the ground cable lug to make good electrical connection with bus bar? Wouldn't tin act as an insulator?
    Absolutely not. The wackiest, over the top grounding I have ever done is on cell sites. They have a set of specs that would choke a goat and they use tinned copper for everything. If there were any reason to not use it they wouldn't and the fact that they do use it answers the question for me.
    Once in a while you get shown the light
    In the strangest of places if you look at it right. Robert Hunter

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