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Bulb melted socket after installing dimmer switch

Discussion in 'Electrics UK' started by mjgreen81, 3 Nov 2020.

  1. mjgreen81

    mjgreen81

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    Hi all,

    I have a plain and simple 100w max light fitting in a spare room. I am just about to renovate it to be a nursery so thought it would be a good time to install a dimmer switch.

    The fitting originally had a 100w bulb which I found hummed a lot. After some googling I found this was not unusual and could be resolved by using a lower watt bulb or by trying a 'rough service' bulb that has a thicker filament and less prone to vibration which makes the humming.

    After some hunting around the house I found a 60w rough service bulb and gave this a try. It resolved the humming perfectly, but I found it to be a bit dreary in the room so wanted to try a 100w rough service bulb.

    I order a 100w rough service bulb and just tried it and although there was a little bit of humming at certain levels of dimness, it was much better. However, after 5 minutes or so I could smell burning and noticed that the bulb had actually partially melted the plastic on the light fitting.

    I did notice that the new 100w bulb did seem exceptionally bright. I am sure it was brighter than the previous non rough service 100w bulb I had before installing the dimmer switch.

    What is going on here? Did I get a bad bulb? Or is the dimmer switch not compatible and is somehow suppling more power than it is supposed to?

    Thanks
     
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  3. AndyPRK

    AndyPRK

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    fault bulb.
    or poor contacts on the holder and/or bulb I think. make sure they are shiny before starting again
     
  4. denso13

    denso13

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    Not sure what that means, although I know what you meant.
     
  5. mjgreen81

    mjgreen81

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    Thanks all. Think I will consider switching for an LED fixing as suggested.
     
  6. AndyPRK

    AndyPRK

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    Trouble is you need a special matching dimmer switch too!
     
  7. mjgreen81

    mjgreen81

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    Yeah, that's not a huge problem. I only bought a cheap dimmer switch so don't mind replacing it.

    I am going down a bit of a wormhole looking at my options. I see that some of these LED units come with thier own remote control allowing you to dim, change colour etc. I had no idea there were so many options!
     
  8. AdrianUK

    AdrianUK

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    The dimmer switch can't do this, but one of your other comments :

    Rough service lamps are usually dimmer than their non-rough service friends... any chance you may have purchased a 110V lamp????

    That would explain everything!
     
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  9. mjgreen81

    mjgreen81

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    It's a 100w/110v lamp.

    I thought that as long as it is 100w (which is the max for the fitting) I would be Ok?
     
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  11. endecotp

    endecotp

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    Don’t do any more DIY electrics until your knowledge is massively improved.
     
  12. mjgreen81

    mjgreen81

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    Ok crap, I just read up and have learned something new.

    Can't believe I have gone this long without understanding the significance of the voltage rating on a lamp.

    Embarrassing

    I guess I have just always picked up a bulb from the shop which are always standard 240v. Now they are quite hard to get hold off I didn't check this.

    Lesson learned
     
  13. AdrianUK

    AdrianUK

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    Ah, now everything makes sense!

    No. A 110V lamp is not suitable for direction connection to the UK mains. The UK mains is 230V. As a result the lamp would have seen a voltage much higher than designed, in fact operating at approx twice its design voltage would mean it drew around 4 times the power... it would be more like a 400W lamp. Hence why you observed it to be very bright & very hot.

    This lamp is really intended for a building site which uses 110V lighting for safety.
     
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  14. mjgreen81

    mjgreen81

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    *Cringe* Thanks again
     
  15. SUNRAY

    SUNRAY

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    No I'm afraid not, it doesn't work that way.
    A 110v 100W bulb will be running at about 440W or in round terms more than 4 times as bright.
    The average fan heater will be around 2000W to 2500W so the amount of heat given off by your bulb is somewhere 1/6th to 1/4 of a room heater, so yes it will be very hot and cause a lot of heat damage.

    On top of this rough service bulbs tend to be a yellower light and not as bright, accordingly the reduction of light output means some other form of output and this will be in the form of heat. In other words a rough service bulb is usually hotter than an equivalent standard bulb.

    EDIT:
    I started writing this reply just after message #9 was posted and didn't see the next 4 before posting.
     
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  16. SUNRAY

    SUNRAY

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    If this hadn't been a rough service bulb, chances are it would have blown quite quickly, possibly instantly.
     
  17. RF Lighting

    RF Lighting

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    One firm I worked at kept the 110V and 230V 500W halogen lamps next to each other in the stores. I think everyone who worked there at some point grabbed the wrong voltage lamp and put it in a 230V fitting.

    It went with quite a bang when I did it :LOL:
     
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