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How to connect wall power to PCB?

Discussion in 'Electronic Design' started by Michael Noone, Mar 30, 2005.

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  1. Hi - a board I'm making is switching a 120VAC line. I'm trying to figure
    out how to connect the 120VAC input and output lines to the PCB. Normal
    house wire (solid, 14 awg I think, but I could be remembering wrong) will
    be connected to the board. I was thinking some sort of screw mounting
    system (like that which you see in most home wiring (ie switches, power
    sockets, etc.). Any suggestions as to a manufacturer or a board mount
    device along those lines? Or is there a better way to do this? Thanks!

    -Michael Noone
     
  2. Joerg

    Joerg Guest

  3. Luhan Monat

    Luhan Monat Guest

    There are several types. Each solders to the circuit board on one side
    and provides some type of screw-it-down access for the wire on the other
    side.
     
  4. Ken Taylor

    Ken Taylor Guest

    Hi. I'd seriously consider mounting your switching device off the board so
    that you move any mechanical (and electrical isolation) problems off-board
    also. Solid core cable of that gauge is going to cause you grief at some
    stage. Depending on what your switch actually is, I'd then go for screw
    terminals or lugs (depending obviously on the terminals on the device) for
    the 120VAC and the mechanics of the control signal(s) becomes 'trivial'.

    Cheers.

    Ken
     
  5. Chris

    Chris Guest

    Pull apart an old toaster and have a look. They have power direct to PCB.

    Cheers.
     
  6. John G

    John G Guest

    I really think if you have to ask this sort of question your experience
    and training level is TOO low to be dabbling in mains powered devices.
    I hope this is for your own use and not for production.
    You have a lot to learn before you should attempt this sort of thing.

    Nobody would connect solid wire from outside a device to a pcb.
     
  7. Oh good grief. The moment I read the OP's post I figured someone would have
    said something like this.

    Stop being so eliteist. If everyone followed your advice then noone on
    earth would know how to work with mains voltage since noone is born with
    innate knowledge of mains wiring practice. At some point in the learning
    process everyone has to ask questions (either to other humans or to
    reference materials) and find the answers.

    The mains aren't all that dangerous and besides, everyone dies someday. It
    is only a matter of when and how. I say it is better to live a little and
    take *necessary* risks than to live a life cowering in mortal fear of
    everything and ultimately end up doing nothing in life.
     
  8. John G

    John G Guest

    Yeh but most people learn to crawl before they try to walk and the OP
    does not know enough to be playing with mains voltages without a LOT
    more training.
    Anything less is suicide or murder.
     

  9. You are very judgmental of the OP. Considering the brevity of his post I
    don't see how an accurate or fair assessment of his capabilities can be
    made.

    That said I don't see anything inherently wrong or otherwise dangerous about
    what the OP was suggesting. Granted it is far more common to find products
    that use a captive cable (or a detachable cable with properly molded
    connections) using stranded wire and are plugging into standard outlets,
    than to find a wiring scheme like the op suggested. On the other hand given
    the right circumstances it is conceivable such a wiring scheme would be
    justifiable. Higher power products that will always remain stationary are
    possible examples (ex: house air conditioner). The OP didn't specify what
    his product was or why direct wiring made sense in his application.

    If you can point to a relevant code or safety standard the OP is clearly
    intending to violate, I would be more swayed by your position.
     
  10. Rich Grise

    Rich Grise Guest

    Well, I do, primarily wanting to connect 14 AWG solid wire to a PCB. If
    OP is switching so many amps that he needs #14, then the current shouldn't
    go through a PCB, unless it's specially designed for that kind of current.

    One of the others mentioned a proper relay or contactor, and just do
    the control circuitry on the PCB. That's probably what I'd suggest.
    And stranded wire.

    Thanks,
    Rich
     
  11. I expected it as well, so I didn't take offense :)

    -Michael
     
  12. I'm not quite sure why a cable as you describe would be necessary - this
    device will be mounted within a wall, and will never be moved, thus strain
    on the PCB should be non existent. By the way - I should mention that
    probabaly a total of 5 or so of these will be made...

    -Michael
     
  13. Current should be 2-5 amps. I was planning on just using as wide of traces
    as possible - probabaly about half an inch. I was also probabaly going to
    put these traces on both sides of the PCB. (directly above and below each
    other). The reason I'm using solid wire is because that is what is used in
    house wiring - and thus what will be connecting to the device. Regards,

    -Michael
     
  14. Joerg

    Joerg Guest

    Hello Michael,
    There is another, simpler method used in some X10 wall switches: Wires
    come out of them. These are then connected to the house wiring with wire
    nuts. Not that I particularly like wire nuts or the fact that they
    instruct you to mix stranded wire with the non-stranded house wire under
    these wire nuts...

    I have also seen that method on regular dimmer modules.

    Regards, Joerg
     

  15. Yeah, Well: My money is on some electrical contractor yanking the cable hard
    at some point to see what it connects to (i.e. when it pops out through the
    plaster).
    Be careful of the Insurance; Any mishap may be blamed on you.
     
  16. Joerg

    Joerg Guest

    Hello Frithiof Andreas,
    No plaster in America. It's all run through holes in the wooden studs,
    occasionally tacked in place.

    Regards, Joerg
     
  17. John G

    John G Guest

    Sheetrock internal wall board is often called plaster, plasterboard, or
    gyprock in other parts of the world.

    The material will not matter. The only listing the OP will get is at the
    Undertakers not Underwriters .
     
  18. Chris

    Chris Guest

    Undertakers??

    Would that be due to electrocution? In the country I live the main group of
    people killed by electrocution are electricians. This is due to the
    introduction of RCD (Residual Current Devices) or otherwise called
    earth/ground leakage devices. The general population is now by and large
    protected.

    Cheers.
     
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