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Does switch's Utilization Category AC-15 include a desktop?

  1. Jun 21, 2015 #1
    For reasons beyond understanding, I'm trying to source an industrial limit switch to control the power to a desktop PC. It's run on a switch mode standard computer PSU.

    Most of the limit switches I've looked at are rated 5 amps @ 220 VAC. But they also have an AC-15 rating usually much, much lower, perhaps as low as 0.2 amps. I think that AC-15 applies to electromagnetic loads. Does this include PCs? They don't have much in the way of transformers...

    Otherwise, how can I use a limit switch for controlling my PC?
    Last edited: Jun 21, 2015
  2. jcsd
  3. Jun 22, 2015 #2


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    Limit Switch ??

    limit switches are used for controlling a motor and other mechanical items connected to it

    you have better more clearly explain your use of the term Limit Switch

  4. Jun 22, 2015 #3
    Something like (but not limited to) one of these:-

  5. Jun 22, 2015 #4


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    Relays are used for higher power applications of limit switches.
    Why you'd use one for a computer boggles the mind..
  6. Jun 22, 2015 #5
    The nub of the question. Does power category AC-15 include a desktop PC?
  7. Jun 22, 2015 #6
    I have to rule out relays as this switch will form the mains isolation switch, so there's no power to drive a solenoid... :frown:
  8. Jun 22, 2015 #7

    jim hardy

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    some guidance


    Inductive load stresses the contact on opening. The arc is difficult to extinguish.
    Capacitive load stresses the contact on closing. Huge inrush current flows while the contact is still bouncing..

    The SMPS has huge capacitors. Some limit inrush current , some don't.

    Do you hear a "pop" when you plug it into an outlet ? Do touch-lamps switch off ? That's symptoms of big inrush.
  9. Jun 22, 2015 #8


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    What exactly are you trying to accomplish here? We might have some alternate suggestions for you to try if we knew why you needed to isolate the power.

  10. Jun 22, 2015 #9
    Thanks Jim, just read this. Looks like I'd be better off using a relay somewhere. This means I'll have to rethink my isolation layout.

    Thought: Why then do domestic socket switches not have usage categories? In the UK, they're all rated 13 amps. Doesn't matter if you're switching a welding machine, most powerful vacuum cleaner in the world or fairy lights.
    Last edited: Jun 22, 2015
  11. Jun 22, 2015 #10
    I'm building a pc in the Steampunk style. It will have a large lever on the side to turn it on, based on :-


    There will be two power supplies and other mains equipment inside the computer case, so I'd like an isolation switch upstream of all of this. It would be really cool if the lever switch actually worked for real as the isolator. Just like in those mad scientist films. The limit switch would be the switch operated by the lever's shaft. As it's the isolator, there's no other power available for relays, mosfets etc.

    My plan B is to connect the lever at it's fulcrum to an industrial 16 or 20 amp rotary switch such as:-


    If I can't reliably attach the lever to this switch, I'll have to fall back to plan C and go with a normal toggle switch isolator,, and a relay /limit switch combo to get the lever operational somewhat. This is the least preferred option.
  12. Jun 22, 2015 #11


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    They do make relays that are mains voltage rated coils. You could drive one of those with the limit switch or a microswitch which are generally much cheaper.

    Then you don't need any extra voltages.

    The microswitch type snap action switches come in many different lever styles.

    Another option is to arrange for your steampunk lever to flip a standard light switch internally.

  13. Jun 23, 2015 #12

    jim hardy

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    not a bad idea. Cheap and easily replaced.

    Microwave ovens have an interesting switch in their door interlock system. Usually it's the middle one.
    Two of the microswitches close when the door is closed. They allow current to the relay that powers the big magnetron.

    A third switch, usually a different color, closes whenever the door is NOT fully closed.
    That one is connected directly across power to the magnetron supply.
    That's so that should the other two switches somehow let the magnetron get power with door not fully closed,
    maybe because the door is warped or a relay has stuck shut and somebody opens the door, ,
    it'll blow the power fuse to protect the folks nearby. .
    So that different switch is built to take a large gulp of current.

    Doubtless you'll scrounge around junkpiles for switches.
    If you pillage a microwave oven door switch be sure to get that fuse-blowing one, not one of the little guys for they only switch relays ..
    The numbers on the switch should lead you to its ratings

    I like steam and understand completely. . Good luck. Be careful
    Last edited: Jun 23, 2015
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