Rotary switch contact rating - Help please.

Discussion in 'General Electronics Chat' started by paulktreg, Aug 27, 2011.

  1. paulktreg

    Thread Starter Distinguished Member

    Jun 2, 2008
    611
    120
    Hi

    I have a rotary switch with a current carrying capacity of 5A non-switching, that's fair enough. It is however rated at 150mA switching @ 250V AC/DC. Could this switching current be safely increased at only 12V DC and by how much? If you took a proportional figure based on power then it would be a little over 3A at 12V DC but does it work that way? The actual data sheet of the switch in question is here but it doesn't give a 12V DC rating.

    Any help appreciated.

    Paul
     
  2. eblc1388

    Senior Member

    Nov 28, 2008
    1,542
    102
    When the contact opens, there will be arcing and this limits the actual current value that can be safely switched.

    I would adhere to the same 150mA current rating at 12V, but I think it would probably be OK to switch a bit more current like 300mA at 12V, but no higher.

    This is nowhere near the 3A that you have calculated based on power. It does not work like this.
     
  3. paulktreg

    Thread Starter Distinguished Member

    Jun 2, 2008
    611
    120
    Thanks for that it's as I expected after looking at ratings on other switches and it looks like I'll have to find myself an heavy duty rotary!
     
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