Buzzing Dimmer and MCB

Discussion in 'Electricians' Talk' started by Accaman, Jun 5, 2010.

  1. Accaman

    Accaman New Member

    I fitted 7 x 240 11W Megamann downlighters yesterday,no probs.Went this morning to replace double switch with double dimmer and this causes not only dimmer to emit a buzz but its mcb to at the cu.Have put back normal switch for time being.
    What do u reckon is causing this? p.s bulbs are dimmable type...
     
  2. Removed 4

    Removed 4 New Member

    This isn't uncommon, Acca: The combination of those types of lamps with a cheap dimmer will often generate a dirty circuit and expose a clapped-out loose part in an old MCB - or a cheap new one.

    Try replacing the MCB first. If that doesn't work, then get a decent dimmer switch - and if that doesn't work, get shot of those silly lamps - and if that doesn't work: recommend a full rewire of the property......

    Lucia.
     
  3. Accaman

    Accaman New Member

    Thanks...:) What do you mean by dirty circuit..?
     
  4. Removed 4

    Removed 4 New Member

    Certain combinations of components on an AC supply, Acca, lead to little spikes and hiccups to the supply.

    The best way of explaining it, dear is the analogy of soiled underpants: You know - when you've been wearing the same pants for four days, and then you decide to have a wash and don a fresh pair of pants? Isn't that a wonderful feeling?

    Megaman lamps + cheap dimmer switch + cheap MCB = soiled pants.....



    Lucia x
     
  5. Accaman

    Accaman New Member

    I thought £20 for a dimmer was pricey ,oh well....
     
  6. Removed 4

    Removed 4 New Member

    And so it is - so it's probably a reasonable quality dimmer.

    Change the MCB then - but still expect the dimmer to give off a slight buzzing...


    Lucia x
     
  7. syholl

    syholl New Member

    Those Megaman bulbs require a multiplication factor of 6 when choosing a dimmer, according to their website. So your 11w lamps actually work out as requiring a dimmer capable of handling 462 watts.
     
  8. Accaman

    Accaman New Member

    Im not disputing your reasoning, syhol, but where did you you get this factor of x 6 from.??? just curious..:)
     
  9. unphased

    unphased Screwfix Select

    Hello Steve

    I had a similar issue with dimmable Megaman lamps and if you make enquiries to them they are very helpful. They are aware that their lamps are not compatible with some dimmers. They can give you advice as to the compatibility of the one you have used and will recommend alternatives. They also advise allowing the lamps to go through an initial warmup time before attempting to dim them.

    Apologies if I have repeated what other posts have said I just read you opening post.

    :)
     
  10. syholl

    syholl New Member

    Accaman, just had a look on their own website, and it has changed since i went on there. They now list some specific dimemrs that will work with their lights. I did find this however....

    http://www.alertelectrical.com/Lamps-And-Tubes/Energy-Saving-Light-Bulbs/Reflector-Low-Energy-Light-Bulbs/Megaman-11w-GU10-Dimmerable-Reflector-417699.asp

    Check out the table, which tells you what size dimmer you need. It works out at about a factor of 6, as i stated before. I was originally told this value by a sales rep.
     
  11. Accaman

    Accaman New Member

    Cheers ..:)
     

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