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Fluorescent light ballast/choke rating.

Discussion in 'Electrics UK' started by dhc, 3 Jan 2009.

  1. dhc

    dhc

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    Hi,
    How are fluorescent light ballast/choke units rated?
    I'm restoring a 1950s display cabinet which is lit by two fluorescent lights, each of which has the tube terminal fittings with intergral starter unit fitting but originally had separate choke unit(s).
    At the moment one light is disconnected, whilst the other is connected, and working, through a choke with these markings: Welter 1xGU20, lamps Ind. 1x20/59, A 0.370, Cos 0.35.
    The two lights take T8, 18w, 24"/60cm tubes and are on 240v mains. Can I run the two lights in parallel from one choke unit and what rating should the choke unit be? (Is the current choke unit sufficient for the two lights?)
    The terminals on the current choke unit are not marked. Does polarity matter on a fluorescent light circuit?
    Thanks for any help,
    dhc.
     
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  3. Spark123

    Spark123

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    Short answer is no - you need to have one choke per lamp.
    The size of the choke is dependant on the size of the tube (wattage).
    Can you post a piccy of the choke and arrangement? I take it you know that the choke etc needs to be inside some sort of enclosure?
     
  4. pte440

    pte440

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    if they are 18/20w lamps you can run them in series, but you woud need a 40w choke and series starters.
    you could get a 2x 18w hf ballast which would run both lamps for about £20
     
  5. Spark123

    Spark123

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    I'm puzzled with the reference to GU20 ? Thought this was an endcap associated with halogen?
     
  6. 333rocky333

    333rocky333

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    you could not use them with a High Freq ballast and they would need to be replaced.

    H/f will not require starters.
     
  7. dhc

    dhc

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    Hi, Guys,

    Those very quick replies from you three guys have given the info I need.
    Thanks.

    Spark123,
    I'd picked up the connection between GU20 and halogen lamps but thought the reference on my existing ballast unit might be from an old, out-of-date rating system. When you say the choke needs to be in some sort of enclosure, do you simply mean not exposed. Its screwed to the inside of one of the wooden sides and is behind an internal panel, so it's out of sight and out of reach.

    pte444 & 333rocky333,
    While I've been checking what's available on-line I'd found the h/f ballast units that don't require starters and some of which power 2 tubes, and that's where that part of my question came from.

    I'll stick to separate choke units which I've found for about a fiver each
    (and which have marked terminals)
    www.tlc-direct.co.uk/Images/Products/size_3/FGCK20.JPG

    Thanks for your help,
    dhc.
     
  8. Spark123

    Spark123

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    I don't think it is advisable to have a choke screwed directly to the wood, they get fairly hot in use, they often rely on the a metal casing for earthing them or a plastic enclosure for insulation.
    Wondering if it would be easier to just buy fittings like these? http://www.tlc-direct.co.uk/Images/Products/size_3/FGMLP8.JPG
     
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  10. Steve

    Steve

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    HF ballasts wont hum.

    Those cheapo ones will.
     
  11. flameport

    flameport

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  12. RF Lighting

    RF Lighting

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  13. Stoday

    Stoday

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    If you do buy those fittings, buy some spare tubes too.

    In my experience, the tubes and fittings don't last long and the tubes come in at least 3 different lengths for 20W tubes.
     
  14. Spark123

    Spark123

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    The screwfix ones?
    From experience those ones from TLC take the bog standard T5 tubes and last a long time too.
     
  15. dhc

    dhc

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    I'd been trying to stick with the original fittings when it really wasn't necessary because the ballast unit and wiring are concealed anyway. So I'll strip them out but hold on to them so they can be re-instated and change to a modern 2-tube h/f ballast unit which can be well earthed and insulated (I've found wiring diagrams for them).
    The finished cabinet will look the same.
    Thanks for all your ideas and advice.
     
  16. DIYnot Local

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