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AC and DC on the same relay?

Discussion in 'General Electronics Discussion' started by torea, Sep 17, 2011.

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  1. torea

    torea

    12
    0
    Sep 1, 2011
    Hey all,

    I have a project that needs AC and DC to be switched by the same switch. Instead of rewiring my vintage switch, I want to use the vintage switch to control a DPDT relay that controls the AC and DC. I found a relay that is rated for 250VAC and 125VDC.

    Can I safely use this relay with AC on one set of contacts and DC on the other?



    Thanks for the help!
     
  2. Resqueline

    Resqueline

    2,848
    2
    Jul 31, 2009
    I don't see any immediate issues with that. The contact sets will have sufficient creepage distances that it should be safe for the intended application.
    Just make sure that the wiring & solder/connection method is safe & insulated so the wires can not come/vibrate/break loose and touch each other.
     
  3. torea

    torea

    12
    0
    Sep 1, 2011

    Cool, thanks! Nobody else on several other forums seems to have been able to give me an answer. As a precaution, should I plan on putting some liquid electrical tape on the solder joints? Or do you think it'll be ok without?


    Thanks again!
     
  4. Resqueline

    Resqueline

    2,848
    2
    Jul 31, 2009
    At least any high voltage or mains AC should be insulated. Does the relay have solder tabs with holes, or is it just pins for PCB mounting?
    Solder tabs with holes; put the wire through the hole and bend the wire back on itself so it's secure before soldering. Cover with shrink sleeve or liquid tape.
    Pins only; make a small sleeve by coiling a thin solid wire. Put this around the pin and the wire before soldering. Cover with shrink sleeve or liquid tape.
    The basic idea of the two procedures is that the solder needs some mechanical assistance to ensure the connection doesn't come apart if stressed.
    Some relay pins are also quite thin and fragile, and in this case it's essential to secure the wires so they don't vibrate and put stress on the relay pins.
     
  5. torea

    torea

    12
    0
    Sep 1, 2011

    Thanks for the advice!
     
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