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Common LED Wattages?

Discussion in 'Landscape Lighting' started by wbaptist, Aug 6, 2010.

  1. wbaptist

    wbaptist Inactive
    Posts: 54

    What is the common wattage LED used in landscape lighting?
    What is the rule for LED wattage vs. Halogen?
    Does a 1 watt LED replace a 20 watt Halogen?
    What is the highest wattage LED fixture available today for outdoor lighting?
  2. bcg

    bcg LawnSite Bronze Member
    from Tx
    Posts: 1,835

    4W LED = 20W Halogen
    8W = 35W
    12W = 50W
  3. INTEGRA Bespoke Lighting

    INTEGRA Bespoke Lighting LawnSite Platinum Member
    Posts: 4,102

    Sorry guys but there are just way more factors involved in LED light sources that make it impossible to compare a x watt LED to a x watt Halogen. There are no hard and fast rules like those that BCG listed.

    The efficiency (lumens per watt) on LED lamps and fixtures varies widely. Then you also get into correlated colour temperature comparisons. A 4000K LED will produce significantly higher lumen output per watt input than a 2700K LED.

    You need to know the key specifications when choosing LED product in order to make a comparison to their incandescent counterparts.
  4. indylights

    indylights LawnSite Member
    Posts: 167

    Aren't you an engineer or technical guy for a lighting manufacturer? Shouldn't you be telling us the answers to those questions? Just one more reason I have started using less and less Unique. Customer service has taken a nose dive this year.

    Scott Maloney
    Sunflower Landscapes
  5. steveparrott

    steveparrott Sponsor
    Posts: 1,196

    BCG's numbers are a good place to start (typical of many LED's on the market), but James is right that there are many factors involved - many LED fixtures and lamps vary from this considerably.

    We should really be considering lumens (lm) per watt (efficacy). Typical incandescent MR-16's have the following lumen values: 20W (300 lm); 35W (500 lm); 50W (900 lm). These tungsten halogen sources therefor have lm/W of between 15 and 18.

    LED lamps can range between 20 and 70 lm/W. Taking the highest value of both lamp types gives us a rough conclusion that LED's are about 4 times more efficient than incadescents. So, based on efficacy, you can divide incandescent wattage by 4 to achieve (a rough) equivalent LED wattage.

    But this is not always the case (in fact DOE Caliper results show huge variations among manufacturers). An LED chip can be made to produce a range of lumen and efficacy values. These are primarily controlled by two factors - voltage through the chip (forward voltage) and the presence of coating (primarily phosphors) on the chip to control color.

    If forward voltage is increased then both lumens and efficacy are increased. This sounds like a good thing, but higher forward voltage increases heat production. As we all know, heat management is the primary problem with high brightness LED's - especially in landscape lighting applications. So, be very suspicious of very high brightness LED lamps - they may fail prematurely in an enclosed fixture.

    The second factor that affects lumens and efficacy is the presence of the phosphor coating. LED's without any coating produce light in very narrow frequency peaks and are perceived as very poor sources of illumination (low correlated color temperature(CCT)). To spread out these peaks and better achieve something closer to incandescent light, mfgs apply a phosphor coating to the chip. The coating greatly improves color but it also decreases lumens and efficacy. So, be very suspicious of very high brightness LED lamps - they may have very poor color quality.
  6. emby

    emby LawnSite Senior Member
    from Ontario
    Posts: 380

    Great information everybody. Thanks.

  7. wbaptist

    wbaptist Inactive
    Posts: 54

    Let me clarify. I am looking for input from the field.

    What is the common wattage LED used in landscape lighting? Is it a 4 watt mr16 drop in, 12.4 watt integrated unit or a 2 watt bipin. I just want to see what people are using.
    What is the rule for LED wattage vs. Halogen? What do guys use in the field? If they have a fixture with a 20 watt halogen lamp do they use a 4 watt led or a 12.4 watt led?
    Does a 1 watt LED replace a 20 watt Halogen? This question is asked to us all the time. "doesn't a 1 watt LED produce us much light as a 20 watt halogen". I asked this question to see if this is the belief in the field.
    What is the highest wattage LED fixture available today for outdoor lighting? I really don't know this answer.
  8. Tomwilllight

    Tomwilllight LawnSite Senior Member
    Posts: 284

    Steve Parrot says above "in fact DOE Caliper results show huge variations among manufacturers" and he is absolutely correct.

    Caliper shows major performance variations among LEDs. Over time, most LEDs available now will change color and lumen output in difficult to predict ways. AND 25% of the LEDs tested didn't even last 1000 hours.

    Please allow me a longer quote from the report Steve referenced.

    "Due to the range of behaviors and rapid rate of change of SSL technology, buyers and specifiers should be wary of all product life claims. More than half the SSL products subjected to CALiPER long-term testing will not provide 70% of initial light output at 50,000 hours and already exhibit significant color shift within the duration of the CALiPER long-term operation. About one quarter of the SSL products would not pass a simple 1000-hour operational test: they do not last as long as a traditional incandescent lamp. On the other extreme, a few products show negligible lumen depreciation after more than 12,000 hours of operation — demonstrating that at least in some cases, the potential for very long SSL product life appears to be achievable."

    Find & read it yourself @ <http://apps1.eere.energy.gov/buildings/publications/pdfs/ssl/caliper_round-10_summary.pdf>

    Frankly, with changing lumen output, color shifting and greatly variable lives, I don't think it's possible to answer the questions you ask at this time. The technology is changing so quickly it is difficult to make comparisons.

    The good news is that the report acknowledges that some LED product IS performing very well after 12,000 hours of continuous operation. That is a long time... About the life of HID and under-voltaged MR16 lamps....

    My suggestion is that you obtain (invest in) sample LED replacement lamps and Luminaires with dedicated LED's and decide for yourself what works for you. The most useful time I've spend in the last few years was my trip to Las Vegas to LightFair last May. I looked, I invested in samples and I've learned.

    Now I've got them hanging in my garden... and I'm watching.

  9. steveparrott

    steveparrott Sponsor
    Posts: 1,196

    I concur with Tom's remarks.

    Why would you want input from the field? The field is populated with all sorts of LED's from many manufacturers whose claims are suspect. I hear all the time that homeowners insist on LED's for their landscape lighting. Installers comply and install whatever fits and whatever a salesman has recommended. They don't know how the lamps will function one or two years down the road - no one does.

    Having said that, there are some promising entrants and within this next year we should start seeing which units hold up and deliver.
  10. wbaptist

    wbaptist Inactive
    Posts: 54

    I just want to know what people are using. I don't care about the manufacturer. I just want to see what is being used. Is a 4 watt, 6 watt, 8 watt, 10 watt or 12 watt the most commonly used bulb?

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