Dimmer Technology - Explained

Discussion in 'Landscape Lighting' started by INTEGRA Bespoke Lighting, Jan 18, 2010.

  1. INTEGRA Bespoke Lighting

    INTEGRA Bespoke Lighting LawnSite Platinum Member
    Messages: 4,102

    Just found this really good resource for explaining the difference between Leading Edge and Trailing Edge dimmers.


    Leading edge = inductive / magnetic
    Trailing edge = electronic

    Leading Edge Dimming - the early part of each sine half wave is chopped off
    Suitable for

    * All resisitive loads (ordinary incandescent lamps, high voltage Halogen, etc.), marked with „R“
    * All inductive loads (Coils, low voltage halogen with conventional transformer, etc.), marked with „L“

    So a marking "RL" indicates the suitability of a dimmer for resistive and inductive loads. Not allowed on these dimmers are capacitive loads (see below).

    Trailing Edge Dimming - the latter part of each sine half wave is chopped off
    Suitable for

    * All resistive loads
    * All capacitive loads such as Low-Voltage Halogen transformers or primary dimming electronic ballasts. Indicated by a "C").

    Do not operate inductive loads on this kind of dimmers - this will usually destroy the dimmer. Resistive loads are suitable for both dimming methods. However, Trailing Edge Dimming offers a softer mode of operation for the lamps and will extend lamp life.

    Please note that some of the cheaper trailing edge dimmers in the market are only suitable for resisitive loads.
  2. David Gretzmier

    David Gretzmier LawnSite Gold Member
    Messages: 3,645

    ok, silly question James- does this mean you can use a dimmer from the local hardware store to dim low voltage lights between the trans and the lights? I have used standard 120v switches for this purpose, but not a dimmer. I could only think of a few purposes for a dimmer, like maybe an overhead on a pergola, but which dimmer serves that purpose?
  3. INTEGRA Bespoke Lighting

    INTEGRA Bespoke Lighting LawnSite Platinum Member
    Messages: 4,102

    David, no you cannot use a standard dimmer to dim the secondary side of a LV circuit. The 'standard' dimmers off the shelf will not work with input voltages below 110Vac. Also remember the increased amperage we are dealing with on LV circuits; standard dimmers are not rated for these loads.

    You can however use the Zane LV dimmer on those secondary circuits.

    With more and more electronic LV transformers being used, and with more people doing more things with integrating existing line voltage lighting into their landscape lighting sytems I thought it would be good to post the differences in dimmer technology here.

  4. RLDesign

    RLDesign LawnSite Member
    Messages: 145


    I found this helpful. So what should the dimmer read if I am trying to have the best dimmer to save lamp life? Also, when is LED going to be dimmable?
    Is that the holy grail right now?

    It is common for me to have multiple dimmed zones on a project, so my jump to UPB was way overdue. Thanks again.


  5. INTEGRA Bespoke Lighting

    INTEGRA Bespoke Lighting LawnSite Platinum Member
    Messages: 4,102

    Tanek, the dimmer you use is determined by the type of ballast/transformer in use. You cannot use an inductive/magnetic dimmer on an ELV transformer, nor can you use an ELV dimmer for a magentic transformer.

    You can sometimes get away with using an incandescent dimmer with an ELV transformer, however you will generally get poor dimming results and can damage the ELV transformer over time. If you do this you will find that your max output is cut to about 85% and your min output is reduced to around 10-15% = Not ideal.

    You cannot use an incandescent dimmer on an inductive/magnetic transfomer.

    If you are using UPB to dim ELV tranformers, you should look to PCS as they are the only company making dedicated ELV modules. Simply Automated says they are working on ELV modules, but they have been saying this for some time now.

    Hope this helps and does not confuse.
  6. RLDesign

    RLDesign LawnSite Member
    Messages: 145

    Thanks James. I will need this info for the UPB/ELV piece, when I make a bigger jump to low-voltage indoor. I am hoping that Qtran will be an option for me within the year, because the stuff looks so darn cool.

    Best, Tanek
  7. INTEGRA Bespoke Lighting

    INTEGRA Bespoke Lighting LawnSite Platinum Member
    Messages: 4,102

    Q-Tran is very cool indeed. It is however the Bentley of power systems. Specification grade and beyond. It takes a very motivated client to shell out for it (in my opinion) and I know because I have tried to 'sell it' to several clients, all of whom failed to see the value in using it. I know it is superior, I know it is trick, I know it is robust, but it is a darned hard system to sell given the price point, even to the most well-heeled clients.
  8. GreenswardLLC

    GreenswardLLC LawnSite Member
    Messages: 17

    Thanks for the info on Zane dimmers, I just called my light distributer last week and he told me there was no such product.

    Greensward LLC
  9. RLDesign

    RLDesign LawnSite Member
    Messages: 145

    Call Gerry at Terradek. 763-577-2425 He will get you the best price.

    Talk soon.


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