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Thread: sp st momentary contact that looks like sp

  1. #1
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    sp st momentary contact that looks like sp

    Is there any sp st momentary $ that doesnt key both sides?
    I cant find it
    110v 3 amp would be fine

    thanks!
    "A problem clearly stated is a problem half solved."

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    Quote Originally Posted by wyreman View Post
    Is there any sp st momentary $ that doesnt key both sides?
    I cant find it
    110v 3 amp would be fine

    thanks!
    Can you be more specific?

    SPST would be two terminal, one contact point - could be NO or NC.

    Momentary likely means you push, pull, turn, etc. but it spring returns to original state once you let go.

    I don't have any idea what "key both sides is supposed to mean", especially when taken with SPST. If you had multi poles and multi throws I could see a possibility of some contacts not changing state when the switch operator is moved to certain positions and that is what I would consider "keying" but you can't have such a thing with SPST there is only one switch to key and only two possible states to go with only two possible operator positions.
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    on the load again

    Basically, does a single throw momentary contact only actuate in that single way, or does it actuate both ways and
    only one direction throws the load?

    a momentary contact that looks more like a vizio timer than a decora rocker.
    The vizio timer can just be pressed in one direction.
    Leviton VPT24-1PZ Vizia 24-Hour Programmable Indoor Timer with Astronomical C... https://www.amazon.com/dp/B003AIKQZ8..._wZNSCb2ZHXYW5 via @amazon

    This was the switch that was supposed to be specd
    The decora rocker style momentary contact switch that was installed can be pressed both up and down
    https://www.legrand.us/radiant/produ...70stmwcc6.aspx
    but the switch that is in the wall actuates like a 2pole

    I didn;t pull the switch, I was all day on the load
    https://photos.app.goo.gl/2gDbW8kBKV6K5Kn66
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    Quote Originally Posted by kwired View Post
    ... you can't have such a thing with SPST there is only one switch to key and only two possible states to go with only two possible operator positions.
    so if there are 3 possible positions
    nothing happens [no wire connected to 2p st]
    open center off
    close common to terminal
    then it must be a 2p momentary contact switch

    A single pole single throw will have only... wait for it...


    ...
    a single throw
    Meaning it can only be actuated one way, like the vizio


    thanks!
    "A problem clearly stated is a problem half solved."

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    Quote Originally Posted by wyreman View Post
    so if there are 3 possible positions
    nothing happens [no wire connected to 2p st]
    open center off
    close common to terminal
    then it must be a 2p momentary contact switch

    A single pole single throw will have only... wait for it...


    ...
    a single throw
    Meaning it can only be actuated one way,
    like the vizio


    thanks!
    That kind of a major item I tried to mention, single throw only has two possible conditions with the contact, open or closed, and "single pole" means there is only one contact.

    Mentioning of "momentary" in combination with SPST, tells us there is a spring return to a certain position, that can be with the contact open or closed.

    The Legrand switch you mentioned is what you seem to be trying to describe - SPST, momentary. This one is most likely NO when not pressing on the switch actuator. press on it and it closes, then it returns to open when you release it.

    If what is installed can be pressed up and down, it is not a momentary switch, the momentary should want to return to original position before you pressed it. What is there is probably standard SPST, not momentary, no spring return. Basically a standard single pole wall switch for general lighting use.
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    If a single pole switch has three positions (down, center, up), then it may be center open, down momentary (spring return) and up maintained. As long as there is only one set of contacts to be actuated you could call it a single throw contact set even though the actuator has three positions.
    Much more common is the double throw switch with the upper position closing common to upper contact, the down position closing common to lower contact and the center position being off (no contacts closed.
    For specialty uses such as motor reversing the mechanism way enforce pausing in the center position (releasing pressure on the toggle) before allowing continued motion the the other position.

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    Quote Originally Posted by GoldDigger View Post
    If a single pole switch has three positions (down, center, up), then it may be center open, down momentary (spring return) and up maintained. As long as there is only one set of contacts to be actuated you could call it a single throw contact set even though the actuator has three positions.
    Which you are more likely to see out of some kind of limit switch than a typical "wall switch"
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    So you want a switch that turns on when you activate it, then turns off when you let go of it?

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    Quote Originally Posted by 480sparky View Post
    So you want a switch that turns on when you activate it, then turns off when you let go of it?
    Sounds like that is what was specified, but what was installed is a typical maintained both ways toggle switch.
    I live for today, I'm just a day behind.

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    https://www.leviton.com/en/products/1257
    Look around till you find your switch, looking in the McGill switch catalog will help you see the different types of contact configuration; you can use a double pole as a single pole too.

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