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Ethernet and Power Cables

Discussion in 'Electronic Basics' started by Rene, Oct 24, 2004.

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  1. Rene

    Rene Guest

    I was told that it is not a good idea to run a power (120 AC) cable together
    with an Ethernet cable because the AC cable would disrupt the transmission
    on the Ethernet cable.



    Is this true? If tit is, is there a way to have the power cord shielded so
    that it does not bother the Ethernet cable or vise versa? Can I buy cables
    that already include a shield on them?



    Thank you.
     
  2. peterken

    peterken Guest

    There's another very good reason for not putting data together with mains,
    it's called safety..... :-S
    Minimal distance is 30cm if no wiring tubes are used over the individual
    lines.

    And indeed, voltage spikes on mains *might* momentarily disrupt data
    traffic, or even damage databuffers due to induced spikes




    I was told that it is not a good idea to run a power (120 AC) cable together
    with an Ethernet cable because the AC cable would disrupt the transmission
    on the Ethernet cable.



    Is this true? If tit is, is there a way to have the power cord shielded so
    that it does not bother the Ethernet cable or vise versa? Can I buy cables
    that already include a shield on them?



    Thank you.
     
  3. Clarence

    Clarence Guest

    Electrical code does not permit power and low voltage signals to run in the
    same conduits or channels. Shielded or not.

    Interference? Not much, I would guess.
     
  4. Jack// ani

    Jack// ani Guest

    My ac cable and the utp ethernet cable are running one upon the other,
    although this is not considered a good practice, but believe me; I
    never noticed any disturbance yet.
    Then go for a stp cable.
     
  5. Rene

    Rene Guest

    Electrical code does not permit power and low voltage signals to run in
    Not even if power is only 12 volt DC?
     
  6. peterken

    peterken Guest

    "Power" means "electrical dangerous voltage-levels", in Europe the
    "dangerous level" is set to 48V.
    Usual indication of "power lines" in this context is "mains supply"...


    Not even if power is only 12 volt DC?
     
  7. Rene

    Rene Guest

    That is fine how ever, pulsing loads on the DC line could
    Even if the CAT5 cable is shilded?
     
  8. w_tom

    w_tom Guest

    Changing currents of how much will induce what frequency on
    adjacent CAT5 wire? Junk science is widespread and prolific
    when we forget to apply numbers to our theories. Please
    provide numbers for these fields generated by changing loads
    on a 12 VDC wire. With those defined fields, what sort of
    voltage and current is induced upon twisted pair CAT 5 wire?
    Anything is possible in a fiction world where we fear to
    provide numbers. Numbers provide a perspective called
    reality. What are those numbers?
     
  9. w_tom

    w_tom Guest

    Don't even worry about shielding. That is 60 Hz field -
    very low frequency - induced on tightly twisted pair wires.
    Almost no coupling exists. Furthermore any minuscule currents
    induced on the CAT 5 wire are made irrelevant by baseband
    signaling equipment (NICs) that operate in megahertz
    frequencies. What he failed to provide are numbers - the
    perspective that makes the problem "insignificant".

    Others have defined a more significant parameter - human
    safety. Power and communication wires must have some
    separation for human safety reasons. Once that necessary
    separation exists, then coupling is made even less significant
    than "insignificant".
     
  10. peterken

    peterken Guest

    Changing currents of a specific frequency on one line will induce induce
    identical AND harmonic frequencies onto the other.
    The level of induction depends upon the distance between the lines
    (reverse-square of the distance)
    The intent of "twisted pair" is to have an induced current to be identical
    in both wires, thus (theoretically) eliminating a voltage-difference between
    both wires of one loop.
    Thus the level of induction depends upon the size of the "spike" in one line
    AND it's actual frequency AND the "not-perfectness" of the twisted pair AND
    the distance between the line and the twisted pair....

    One can of course take the datasheets of a specific twisted pair and begin
    calculations until your hair turns grey, but that was not the point of this
    thread.
    The point was to inquire if power lines could be aside datalines and what
    were contra-indications to do so, nothing else...
    Personally i prefer to leave the math to the designers of the cables, and
    just apply "rules of best craftmanship"....

    <quote: One can be born silly, then rocked daft in the cradle, and still
    study until completely nuttyness arises....>



    Changing currents of how much will induce what frequency on adjacent CAT5
    wire?
    Junk science is widespread and prolific when we forget to apply numbers to
    our theories.
    Please provide numbers for these fields generated by changing loads on a 12
    VDC wire.
    With those defined fields, what sort of voltage and current is induced upon
    twisted pair CAT 5 wire?
    Anything is possible in a fiction world where we fear to provide numbers.
    Numbers provide a perspective called reality.
    What are those numbers?
     
  11. Jamie

    Jamie Guest

    That is fine how ever, pulsing loads on the DC line could
    induce cross talk problems in crappie communication cables like
    CAT5 and the like over a long hall.
     
  12. Dbowey

    Dbowey Guest

    Jamie posted:
    --

    How about sharing some of that vast experience and tell us how induced voltage
    unbalances a balanced cable pair by "influencing the signal." What work did
    you do in that lab?

    Don

    --
     
  13. Jamie

    Jamie Guest

    well if its shielded then you should be ok how ever, most
    cat 5 i used is not shielded but that doesn't mean you
    don't have a good supply of the shielded type.
     
  14. Jamie

    Jamie Guest

    I guess working 21 years in a lab
    performing Lost, Skin, Radiated, and velocity
    tests in a work area that has made
    electronic wire and cables for 50 years
    isn't enough ?
    To let you in on something, our
    facility was one of the first to
    start massive manufacturing of CAT 4,5
    and the like along with the foam pairs
    bundled with twisted pairs of control
    wires etc...
    high levels of DC currents pulsing
    over long runs bundled in the same
    race way with no form of EMF shielded
    does un-balance the Twisted pairs there
    by influencing the signal.
     
  15. Jamie

    Jamie Guest

    bandpass, cross over, burn test for smoke, copper purity, rip cord break
    with out deforming pairs.
    Practical application testing, one of them just happens to be a a
    test that requires a length of a 100' to be laid along in side of a race
    way
    with mounts that have a high current lines. the CaT is placed in a
    holder that places it 1 " away from the high current lines which AC and
    DC currents are generated up to 500Amps while monitoring the twisted pairs..
    this test tell us how consistent the twisted pairs are and how well
    they are bunched together. twisted pairs that are not uniform at the
    correct the lay will show uneven readings under AC currents..
    etc..
    P.S.
    we are currently making some CAT wire with combined Optics and
    rein forced binders made of Kevlar along with some high current control
    wires as a composite cable to be used in future homes and businesses.
    should be interesting. we have never combined those types of components
    in one cable before.
    so far, testing on the samples appear to be passing very well on the
    CAT and control wires. i think this maybe due to the fact that we have
    put lightly braided shield around those.

    Btw.
    putting Cat wire in a race way that houses high current wires for
    drives DC/AC has prevent to not work well for our electricians. it
    took them aprox 3 mounts of playing around with a machine that was
    having a very slow response rate reading data from controllers via a
    Cat 5 . it turned out that, many errors were being generated in the
    interface and thus the network connection was doing alot of resends
    or waiting for updated readings thus causing the machines performance
    to be unpredictable.
    running the CAT 5 in its own race way solved that problem.
     
  16. Dmitri

    Dmitri Guest

    Jamie,

    I hope you still re-visit this old post from time to time.
    I'd like to learn more about the tests you are referring to. What kind of
    currents you are talking about? What do you refer to by pulsing DC in this
    case, switching loads? What frequency? What type of load? What was the
    distance between the cable with DC current and the twisted pair? What was
    the length of the samples? What kind of raceway used? What was the UTP
    terminated on, and how did you measure the mis-balance?
    From your post I got a feeling that you were talking about tests conveyed
    quite a few years back, so I'm sure you'll open no trade secrets by
    posting here (or in comp.dcom.cabling to that matter). Very interesting
    stuff, please continue this thread.

    --
    Dmitri Abaimov, RCDD
    http://www.cabling-design.com
    Cabling Forum, color codes, pinouts and other useful resources for
    premises cabling users and pros
    http://www.cabling-design.com/homecabling
    Residential Cabling Guide
    -------------------------------------



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