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Terminating stranded wires

Discussion in 'Electrical Engineering' started by Ryan Evans, Feb 5, 2004.

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  1. Ryan Evans

    Ryan Evans Guest

    Is it ok to terminate stranded wire around the screws of a device?

    RE
     
  2. Me

    Me Guest

    NO!


    Is it ok to terminate stranded wire around the screws of a device?

    RE
     
  3. EEng

    EEng Guest

    It won't pass UL/CSA/VDE or any other code. Terminate the wire by
    crimping/soldering it to a terminal such as a spade or ring connector
    then put that to the screw of the device.
     
  4. EEng

    EEng Guest

    You just confirmed what I said. USE TERMINALS. Nowhere does it say in
    any code, including NEC that its okay to simply wrap a wire around a
    screw. In ALL cases it specifically mentions using a terminal.
     
  5. EEng

    EEng Guest

    No sir, you're misinterpreting what the quote you sited says. A
    terminal is a specific piece of hardware. There are screws that are
    integrated with wire terminals and there are many types but there is a
    distinct difference between something that is a terminal, and
    something that has been terminated. Example: The wire is terminated
    to a terminal. Terminated is to end something. Terminal is what you
    terminate something to. In the quote you sited below..........A wire binding screw is a terminal. It is not used for assembling
    devices, which is what the OP was asking...."Is it ok to terminate
    stranded wire around the screws of a device?" Note the pictures at
    the URL listed below. These are terminals that utilize a screw as
    part of the terminal structure however they are specifically
    designated as terminals in this case board mounted and are absolutely
    not used for construction of the device itself.

    http://www.zierick.com/connectors/c_binding_post_screw_terminals1.php

    Setscrews, clamping screws, etc are also terminals that utilize a
    screw as part of the terminal, to make the termination of a wire. As
    in barrier strips, the screw clamps the wire to the terminal, but the
    wire is at no time simply wrapped around the screw threads. The
    closest you might get to that is with the screw actuated backwire
    clamp, but note the wire is clamped between two plates, not wrapped
    around the screw threads The UL reasoning for this is that the
    threads of a screw are sharp enough and there is enough tension, to
    cut into the wire thus making it unsafe should the wire be cut
    through.

    One of the better sites with explanations and pictures to demonstrate,
    is http://www.zierick.com

    The OP asked about the screws of a device, meaning the screws that
    are used to hold the device together. IF the device screw is one of
    these types of terminals, then sure, he can use it to terminate his
    wire, but in answer to his direct question.... no, it is never okay to
    terminate a wire AROUND the screws of a device.

    Your quote is excellent, and points specifically to the use of
    terminals.
     
  6. Guest

    No sir, he is not. It is as he said. To verify this
    for yourself, disassemble a UL listed floor or table
    lamp. The stranded lamp cord terminates at the socket
    terminals, and the stranded conductors are wrapped
    around the screws there with no ring/spade/whatever
    connectors.


    <snip>
     
  7. EEng

    EEng Guest

    Well, I have three of those, and each are terminated to a wire binding
    screw, which is a terminal, not a device screw. That little tab of
    metal that is upturned, is to prevent wires from spreading/slipping
    out from under the screw head. It's still a terminal.
     
  8. Ross Mac

    Ross Mac Guest

    In the rare case that I wrap a wire around a screw, I usually strip the wire
    extra long, tin it and wrap it clockwise. Consumer devices such as lamps are
    a good example of when this might occur. The only problem with tinning a
    wire is you need to go back later and re-tighten the connection. Since
    tin-lead is soft, just like the aluminum wire put into homes many years ago
    and has a tendency to create bad connections....
    My two cents...Ross
     
  9. Me

    Me Guest

    EEng is right. If the rest of you would open and read UL's White Book then you would
    know for yourself. Reading the NEC does not give you a license to dispense unfounded
    advice.


    Well, I have three of those, and each are terminated to a wire binding
    screw, which is a terminal, not a device screw. That little tab of
    metal that is upturned, is to prevent wires from spreading/slipping
    out from under the screw head. It's still a terminal.
     
  10. EEng

    EEng Guest

    No limit
     
  11. Guest

    I see that Greg, you and seem to be in agreement. Stranded
    wire can be wrapped around a screw. The UL white book does
    not prohibit such a connection. The screw must be part of one
    of the device's terminals. The difference is that you want
    the more complete description "terminal screw" (which I see
    as obvious by the question). Do I properly understand you?
     
  12. Ross Mac

    Ross Mac Guest

    Funny you should say that....That's how I prepared the wires on my speakers
    binding posts!....Ross
     
  13. Ross Mac

    Ross Mac Guest

    Do we have some poker players here???.....
    Have a great one, Ross
     
  14. EEng

    EEng Guest

    Sheesh I've never seen anyone fight so hard to be wrong. A screw
    actuated terminal is one in which the screw is used to hold the wire
    in place against a constraint that prevents slippage such as a clamp,
    an upturned tab, etc. A mere screw used in the assembly of an
    enclosure is none of these and cannot be used to terminate a wire
    merely by wrapping it around the threads of said screw. UL is very
    specific about using the terminology TERMINAL. If it had meant screw
    by itself, it would have said screw by itself.
     
  15. Ross Mac

    Ross Mac Guest

    I assume we are talking about a barrier strip???
    Just curious...... :>)
     
  16. EEng

    EEng Guest

    Fine, believe what you want. If you can't distinguish between a
    proper terminal and a device screw then more's the pity, and just
    because it is common practice to save money and time by using a
    standard screw AS a terminal when it is clearly not, neither by design
    or by code, doesn't make it right. Between the political BS and
    bottom line dollar, more is done incorrectly on purpose, with
    authorization than is done by the book. Clearly, those who believe
    that a device screw is a terminal, have never worked on anything DOD.

    End of topic out of sheer frustration with those who demand the right
    to do it wrong.
     
  17. Ross Mac

    Ross Mac Guest

    It's a little difficult to tell, by the limited information, exactly what
    the OP was up to. He doesn't mention if it's an industrial or household
    setting or even if he is speaking of a barrier strip. The commercial wiring
    folks that I have used, usually used crimp connectors on barrier strips or
    just pushed the strands into a terminal strip and tightened the screw. The
    key here is that I hired these folks and am not the code expert.....
    Take care.....:>) ...Ross
     
  18. DarkMatter

    DarkMatter Guest

    That is certain.
     
  19. EEng

    EEng Guest


    I suggest you take a much closer look at those switches and
    receptacles. Where the wire goes, there is a small upturned tab. It
    might look like just a screw but its not...its a screw actuated
    terminal because of that little tab, whose sole function is to prevent
    the wire from slipping out from under the head of the screw. That's
    why they're usually so hard to put a wire to, because that tab gets in
    the way. Also consider that UL, NEC and other codes are written for
    one purpose ONLY. It is not for standardization, it is to satisfy
    SAFETY requirements that would otherwise result in lawsuits, etc.

    All the manufacturing codes, installation codes, etc, are written for
    safety. Now, do you honestly believe that with all the safety issues
    addressed in these codes, that they would say its okay to simply wrap
    a wire around just any old screw? THINK. It's obvious you don't
    recognize a terminal when you see one if you believe that the screw on
    receptacles and switches is just a screw.
     
  20. Ross Mac

    Ross Mac Guest

    Isn't that for solid wire as opposed to stranded?
     
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