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Thread: CFL/LED Equivalent Wattage to socket wattage rating question.

  1. #11
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    Quote Originally Posted by gar View Post
    190111-1545 EST

    ritelec:

    An LED bulb with a 60 W equivalent rating has a steady-state input power consumption of about 9.5 W. The equivalent rating means that with 9.5 W of input power the LED puts out a visible light intensity approximately equal to that produced by a 60 W incandescent tungsten bulb. This is relatively correct.

    But that is not all that one must consider.

    Thermal is a major consideration.

    An incandescent bulb can tolerate a high ambient temperature around the bulb without failure. Incandescent bulbs are not very efficient relative to input electrical energy to output visible light. But incandescents produce a lot of IR radiation. The IR energy leaves the fixture just like the visible light does. Thus, a large amount of input electrical energy goes out as radiation, the combination of visible and IR.

    An LED bulb can NOT tolerate a high ambient temperature around the bulb without failure. LED bulbs are much more efficient in conversion of electrical energy to visible light than incandescent bulbs, there is heat generated in the LED to perform its function, but this is at low IR frequencies and therefore wasted energy is not much radiated.

    Thus, combining the LED low tolerance for high ambient temperature with a lot of conducted heat loss inside a fixture you may fail a 9.5 W LED in said fixture where an incandescent would not fail. LEDs need ventilation.

    RFI noise from an LED is another problem.

    ..
    gar, how can LED's have an issue with RFI? Are they controlled by PVM? I thought an LED was a diode and DC comes to mind.

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    Quote Originally Posted by infinity View Post
    I would guess that a standard Edison Base lampholder marked "Max 60 Watts" is the rating only for incandescent lamps. How that translates to CFL or LED's is not (yet) defined by the NEC.
    If the lampholder's marked "Maximum 60 Watts", you can put up to a 60-watt bulb in it, regardless of what kind of bulb it is. That said, it only assures that the lampholder won't overheat. A CFL or LED bulb might overheat and quit working. (but won't overheat and create a fire hazard)

    These are actual watts, not "equivalent" watts. "Equivalent watts" are nonsense.
    However much actual power a bulb consumes is very nearly equal to the amount of heat it dissipates. Even "high-efficiency" CFLs and LEDs convert very little of the input power into visible light.

    The confusion started when the marketing people assumed that the American public is too lazy or too stupid to distinguish between the amount of electricity a bulb consumes and the amount of light it emits. They labeled 15-watt CFLs "60 watt" because they emit the same amount of light as the 60-watt incandescents they replaced.

    Of course, anybody who graduated from a decent high school knows that a watt is a unit of power, not a unit of luminous flux, and the confusion-free method would have been to label them "15 watt" and "900 lumens".

    It doesn't need to be separately defined by the NEC. The lampholder has a limitation and the NEC requires you to abide by every device's limitations.

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    Quote Originally Posted by Gary11734 View Post
    gar, how can LED's have an issue with RFI? Are they controlled by PVM? I thought an LED was a diode and DC comes to mind.
    The semiconductor junction inside an LED is, indeed, a DC device that operates on two or three volts.

    Converting 120 or 277 volts AC to 2 or 3 volts DC is usually accomplished with a switching power supply, (and PWM, if it's dimmable) and switching power supplies are frequently a source of Radio Frequency Interference.

    While they're a source of RFI, I would be very surprised if they're vulnerable to it.

    Likewise CFLs. (but not at 2-3 volts)

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    Quote Originally Posted by ritelec View Post
    Not porcelain 600 watt or ..... B

    Piece of plastic socket that has a sticker on it that says 60w max.

    100w comparable led/CFL ( or larger) no more than 60w led/CFL load permitted ?
    Look at the real watts of the lamp not the pretend equivalent.
    I have 3 pretend CFL 100w equivalent in an old kitchen enclosed drum fixture over my reloading bench that stays on for ~ 6hrs. at a time no problems.

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    Quote Originally Posted by drcampbell View Post
    The semiconductor junction inside an LED is, indeed, a DC device that operates on two or three volts.

    Converting 120 or 277 volts AC to 2 or 3 volts DC is usually accomplished with a switching power supply, (and PWM, if it's dimmable) and switching power supplies are frequently a source of Radio Frequency Interference.

    While they're a source of RFI, I would be very surprised if they're vulnerable to it.

    Likewise CFLs. (but not at 2-3 volts)
    I never really thought of how they were reducing the voltage to 3 V. Are they using common 7805 regulators? I thought of power width modulation would seem to be the easy way to go.

    Recently I put some LED's under in my counters toe area. I have Legrand control lighting all over the house which is running all 12 volts except for some 120 volt lighting.

    I hooked a strip up and the damn things didn't work. OK, what's the problem. This voltage must be AC. Oops, this equipment is based on Halogen lighting! OK, where's a bridge rectifier. Lighting is now on and beautiful...

    I changed 78 20 watt halogen in the ceiling to 3 watt LED, and they worked. I guess they make AC/DC LED and some you have to convert as happened here. Ahhh, now I remember tossing their little transformer that came with the strips! The bridge rectifier must have been in there...



    Thanks gar.

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    Quote Originally Posted by drcampbell View Post
    If the lampholder's marked "Maximum 60 Watts", you can put up to a 60-watt bulb in it, regardless of what kind of bulb it is. That said, it only assures that the lampholder won't overheat. A CFL or LED bulb might overheat and quit working. (but won't overheat and create a fire hazard).
    My point was that the 60 watt maximum labeling on the socket is based on incandescent type lamps.
    Rob

    Moderator

    All responses based on the 2014 NEC unless otherwise noted

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    The light-emitting diode itself is a DC device. It conducts in only one direction.
    But if you were to connect it to AC, (and limit the current) it would light up. It would light up on the forward half-cycle and remain dark on the negative half cycle. It will look like it's just "on" because the human eye isn't fast enough to see it turning on & off 60 times per second.

    7805 regulators could be used, with current limiting. But it would be horribly inefficient; the 7805 is a linear regulator with a forward voltage drop as big as an LED's forward operating voltage. It would also be a lot more expensive than the ASICs (application-specific integrated circuit) that they probably use.

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    Quote Originally Posted by infinity View Post
    My point was that the 60 watt maximum labeling on the socket is based on incandescent type lamps.
    A lampholder's capacity is based on how much heat it can dissipate without its temperature rising enough to become a hazard. It doesn't know or care what kind of lamp is installed; all that's important is that it dissipate less than 60 watts of heat.

    ACTUAL watts, not equivalent watts.

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    Quote Originally Posted by drcampbell View Post
    The light-emitting diode itself is a DC device. It conducts in only one direction.
    But if you were to connect it to AC, (and limit the current) it would light up. It would light up on the forward half-cycle and remain dark on the negative half cycle. It will look like it's just "on" because the human eye isn't fast enough to see it turning on & off 60 times per second.

    7805 regulators could be used, with current limiting. But it would be horribly inefficient; the 7805 is a linear regulator with a forward voltage drop as big as an LED's forward operating voltage. It would also be a lot more expensive than the ASICs (application-specific integrated circuit) that they probably use.
    I will go look for those integrated circuits...

    Thanks

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    Yes, lampholders are rated in actual watts to avoid overheating.
    If it says 60 watts, then it means exactly that. True lamp wattage not to exceed 60 watts incandescent or 60 watts CFL or 60 watts LED.

    In practice it is not likely that one would WANT to fit a true 60 watt LED bulb into a standard socket. Such a lamp will be very large, heavy, expensive and probably too bright in a situation intended for a 60 watt incandescent. But I believe that you could fit such a lamp.

    Here in the UK most plastic lamp holders and lighting fixtures intended for household use are marked "60 watt maximum". Better quality products intended for industrial use may have a higher rating.

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