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Thread: LED lamps with a bayonet cap

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    Lightbulb LED lamps with a bayonet cap

    Sorry if this topic has been covered before, I've done a search and couldn't find anything.

    What are peoples experiences with LED lamps with a normal bayonet cap (as a quick replacement for existing mains lamps).

    I am looking into warm white ones at the moment and there seems to be a lot of choices from cheap and nasty looking all the way up to fully featured and seventy quid each!

    What are experiences and things to watch out for?

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    Moderator toscal's Avatar
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    My company supplies LED lighting. Unfortunately we don't do bayonet fittings.
    Things to check out for are the:
    Lumen value. The higher the value the better. Be wary of manufacturers who only give you a mcd value (milli-candela). Conversion from mcd to lumen isn't that straight forward. http://led.linear1.org/lumen.wiz If they can't give you the lumen then see if they do a lux value. Sometimes this is given in the form of a cone diagram. which shows at varying heights the lux value and beam spread.
    Beam angle.
    Wattage.
    LED type. should be Cree, Edison, Nichia. We use either in Cree or Edison in most of our lights.
    Colour temp the hotter the temp the colder the colour of the light.
    Warranty length, ours is at least 2 years
    Hope this helps.
    Last edited by toscal; 27th October 2009 at 10:27 PM.
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    I just swapped the batten holders out for ES ones in the few places I still had a bayonet lamp socket in the house. The hole for the shade is larger on the ES holders so it can mean some surgery is needed on the shades.

    Table lamps are another matter as they have a very thin ring that goes around the bulbholder for the shade, too small to enlarge and have anything left. Just stuck with incandesents in those for now.

    5 watts is about the minimum you need to actually get some light out of leds - any less and its just decorative.

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    Quote Originally Posted by richms View Post
    I just swapped the batten holders out for ES ones...

    5 watts is about the minimum you need to actually get some light out of leds - any less and its just decorative.
    I think that maybe changing to ES is the way to go then, what brand of LED are you using and what are your experiences?

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    Moderator toscal's Avatar
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    Quote Originally Posted by richms View Post
    5 watts is about the minimum you need to actually get some light out of leds - any less and its just decorative.
    Not true. We supply a 3W GU10 LED bulbs that produce as much light as a 25 to 35 W halogen. We have done extensive tests and measurements. I replaced 4 35W halogen bulbs with 4 3W LED bulbs and measured a before and after lux readings we took 6 readings in various places for each set up. The average reading with the halogen bulbs was 102 Lux , min reading was 52 lux and the max was 133 lux. And with the LED replacements its 115Lux. with min being 38Lux and max being 211 Lux. So obviously an overall improvement. Also these are the main lights in the room.
    We recently did a classroom at a school as an on going project and replaced the 35W halogens with 3W LED lights and there have been no complaints about inadequate lighting.
    The only problem is they do have is the narrow beam angle, but this is improving. And adding an extra one or two more normally solves this.
    Last edited by toscal; 4th November 2009 at 03:11 PM.
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    Quote Originally Posted by toscal View Post
    Not true. We supply a 3W GU10 LED bulbs that produce as much light as a 25 to 35 W halogen.


    The only problem is they do have is the narrow beam angle, but this is improving. And adding an extra one or two more normally solves this.
    There is less total light out of a 3w - the hot spot of the beam is brighter but there is a lot less other light coming from them.

    The ones I was using were globe ones, so giving light in a 360 like a normal GLS lamp does. I would equate the 3w in that situation to little more than a nightlight globe, but a bit higher in colour temperature.

    Now the lamps I had were that horrid warm white not 4000K or 6500K ones, and I know the efficiancy of the warm white is a lot lower than the better ones, but I dont see that making a 3w in a table lamp providing a usable level of light.

    5w in the ones I have (5 1 watt leds) is enough to put some usable light onto the table below it, and see your way in the room around the table. There may be some that have a better output with better leds in them, but that messes the payback calculations to "never"

    The claims of the LED lamp manufactures is just a BS as the individual LEDs, quoting brightness at the brightest point on an impossibly narrow beam to use for anything remotly close to general lighting, which is what it needs to be to replace a GLS incandesent or standard CFL lamp. A row of MR16 replacements over a bench with twice the number of fittings and 3w ones in it works as a replacement for narrow angle 20w lamps in the kitchen, but the reason for that replacement was to get a nicer colour since halogen is only a 3000K at the best of times.

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    Moderator toscal's Avatar
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    Quote Originally Posted by richms View Post
    5w in the ones I have (5 1 watt leds) is enough to put some usable light onto the table below it, and see your way in the room around the table. There may be some that have a better output with better leds in them, but that messes the payback calculations to "never"
    How so.

    Lets do some calculations
    6W MR16 led bulb costs 24 Euros plus tax and will replace a 50W MR16 bulb which costs about €1.10 Both bulbs have a beam angle of 60 degrees.
    The normal MR16 will last 5000 hours the 6W LED will last 50000.
    lets assume 8 hours a day 365 days a year.
    The normal will last 1.7 years
    The LED will last 17.1 years
    Yearly costs for say 2 of each bulb
    Normal 8 x 365 x 2 x 50 = 292 kWh
    LED 8 x 365 x 2 x 6 = 35.04kWh
    using € 0.11 per kWh
    Normal is €32.12/year
    LED is €3.85/year
    saving €28.27/year
    So purely on energy savings the payback time is 1.7 years
    Now when you add lifespans into the equation, you get
    the normal bulbs will need to be replaced 10 times before you replace the LED bulb. So that's another €22.00 you have saved in 17 years. Or €1.29/year.
    So savings are now €29.56/year. Payback time is now 1.6 years or 36 days shorter than before, not much of a real difference.
    Last edited by toscal; 19th November 2009 at 11:55 AM.
    IF YOU CAN'T FIX IT WITH A HAMMER, YOU'VE GOT AN ELECTRICAL PROBLEM.
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