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Conductive Copper Tube

Discussion in 'General Discussion' started by RocketNut, Mar 29, 2021.

  1. RocketNut

    RocketNut Alibre Super User

    Howdy

    I am looking for a copper rod or tube that is electrically conductive but do not know what grade I should use. The max voltage is 75v at 500mA. So I'm wondering if anyone could help me.

    Thank you in advance. ( ͡° ͜ʖ ͡°)
     
  2. DavidJ

    DavidJ Alibre Super User Staff Member

  3. Adi

    Adi Member

    Whatt will be cross-section (area) of the pipe?
     
  4. HaroldL

    HaroldL Alibre Super User

    I thought all copper was electrically conductive. :confused:

    What about using ground rods?
     
    JST likes this.
  5. Adi

    Adi Member

    Yes, all copper alloys are conductive- in some cases (very small diameter/ cross section area/ very long part, or need of very low voltage drop needed- the exact composition may have big influence on effects. There are for e.g some grups of copper alloys that have increased resistance- for use as heating elements
     
  6. RocketNut

    RocketNut Alibre Super User

    Thank you for the great information. :)

    Since the cost of copper rods is so expensive we are changing to copper pipe. I found one on eBay (https://www.ebay.com/itm/Round-Pure...477837&hash=item2621b10113:g:N3MAAOSwL31dKAX3 ) that I think will work for us. The pipe is 20mmOD X 200mm Length wall thick is 1mm. As for the amount of power being passed, is very low (75VAC@2 Amp). We using the pipe to sense contact ( please see attachment) on another copper surface.

    Dart Project 11 Shock Tube 43mm Copper Tube ASM.jpg
     
    Last edited: Mar 29, 2021
  7. oldfox

    oldfox Alibre Super User

    "Copper" is pure copper. Anything less than pure would be copper alloy or dirty copper. And yes, you are right. All copper is conductive.
    Copper is the second best conductor of electricity after Silver. And here again, both metals being pure.

    @ Rocket -- One of the many advantages of using copper tubing as opposed to copper rod is that if you are operating at elevated
    frequencies, then you will start experiencing "skin effect" which simply means that the current will be increasingly concentrated,
    in direct relationship to the frequency, toward the outside of the conductor or skin of the material.

    No need to pay for all of that copper in the middle. Use the money for more tubing.

    Also at elevated power levels even copper will start getting hot with too much power. With tubing you can use a cooling medium
    through the tubing. Already a common practice.

    In post one you state 75 Volts @ 0.5 Amp and in post 6 you state 75VAC @ 2 Amps. That's a big difference.

    According to your specs of 75V at 500ma, that is only 37.5 watts for the layman. You didn't specify the frequency of your system.
    A DC system would consume more power at the same voltage and current level. Think square root of 2.

    Just a little insight into copper as an electrical conductor. Good luck with your project.
     
  8. HaroldL

    HaroldL Alibre Super User

    That's good info about the skin effect. I've heard, or read somewhere, that it is more prevalent on high tension power lines.
     
  9. JST

    JST Alibre Super User

    Not exactly an Alibre issue..................

    Copper is rather easily corroded, and many common pollutants will cause corrosion and build up a coating of non-conductive corrosion products on copper. Plating with tin is quite effective at reducing corrosion in common environments, and stabilizing contact resistance. No plating will, however, resist abrasion for very long, if that is a consideration due to moving contacts, etc.

    As for the high voltage lines, the problem is generally corona type discharge, and the lines are typically made of several conductors held at the corners of a square cross-section so that they act as if they were a larger diameter, reducing the corona effects. The multiple conductors would reduce the skin effect as well, but that is not as much of an issue, although it can be when high currents are a consideration. However the usual reason for high voltage is to reduce the current for a given power transmitted.
     
  10. Jimpulse

    Jimpulse Alibre Super User

    We dont know your application, but at 75vac, it's clearly not a simple control or detection circuit, but I rather guess that as far as conductivity is concerned the grade of copper is mostly irrelevant. almost any common copper pipe will be conductive enough. even with 28 ga wire (.013 dia.) the voltage drop would be less than .2v, calculating to .4 watts of loss.
    I should think a driving concern would be maintaining conductivity as the copper ages and gets corroded. (as JST mentioned)
    You might find that some brasses might be more reliable in the long run, even though their initial conductivity is lower than copper.

    Hear is one of many online voltage drop calculators, it is for wire, but you simply have to convert your tube cross section to circular mils - CMIL
    note these calculators are usually based on 99.9% pure copper.

    Side note common ground rods are usually thinly copper plated steel as copper is too wimpy to withstand the pounding into the ground.
     

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