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Timer Switches

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  • Timer Switches

    Hi All ...

    I have a mechanical 30 minute timer switch that operates a steam unit. It needs replacing and I bought an electronic timer rated at 20A and 1000W. This brings me to question 1:

    20A x 110V = 2200W ... where does the 1000W rating come from?

    Question 2 is:

    the 5A rated switch does not require a neutral ... why does the 20A version? I don't have a neutral in the box - hypothetically if I wired the switch into just Line/Load and didn't connect the neutral, what would happen (I'm sure the word 'fire' is going to show up in your answers)?

    Please satisfy my curiosity ... thanks very much.

  • #2
    Re: Timer Switches

    Incandescent Lamps (light bulbs) have a high inrush current. The filaments have a low cold resistance compared to the hot resistance. The switch is rated for not more than 1000 Watts total of light bulbs. You'll see this on toggle switches in some cases too.

    As for the neutral being needed, most likely that's for the clock. Many mechanical time switches has 110-120 Volt clock motors and the new electronic ones need 110-120 for the control circuit. Carefully read the instructions as there should be some info (wiring diagram) on this. I have seen electronic models that use 1 alkaline AA cell/battery and don't need to be connected to electric power to run the clock in them. Those are nice when you have a power failure as you don't have to reset them afterward.