Connect with us

Lights dimming

Discussion in 'Electrical Engineering' started by Den, Jun 18, 2004.

Scroll to continue with content
  1. Den

    Den Guest


    I need to be lead gently (but not too gently through this one!).

    In my home in California (110V) why is it that (for example) a light will
    noticeably dim when a heavy duty appliance is turned on on the same circuit,
    but not when it is turned on on another circuit?

    Why didn't I see this effect when I lived in the UK (240V)?


  2. Guest

    ckt1 A============Bappliance====lite

    ckt2 A======================Blite
    There will be a voltage drop on the conductors on ckt1 from point A
    to point B when the appliance turns on. ckt2 conductors will not experience
    a voltage drop when the appliance turns on, since they are not connected to
    the appliance.
    Therefore, when you plug the lite into ckt2 it does not dim like it does
    when plugged into ckt1
  3. Den

    Den Guest

    OK thanks for this ... but why wasn't the same effect visible on 240V ... is
    it an effect that is proportional to the voltage or square of the voltage?

  4. Sort of, square of the current actually, all other things being equal.
    It's probably actually worse than this as all other things aren't equal
    (in particular conductor crossectional area for equivalent voltage drop
    losses would need to be 4 times those in the UK for same power circuit).
    See a recent thread where exactly this point was discussed.

    Filamant lamps themselves accentuate voltage fluctuations in their
    light output -- you might find retrofit compact fluorescents and
    regular fluorescents with electronic control gear are better at masking
    the voltage fluctuations.
Ask a Question
Want to reply to this thread or ask your own question?
You'll need to choose a username for the site, which only take a couple of moments (here). After that, you can post your question and our members will help you out.
Electronics Point Logo
Continue to site
Quote of the day