I have to admit my experience with CFL bulbs has been very limited until the
last few years. So I might be and probably am missing something in this
discussion.
No one seems to be accounting for the heat generated by the ballast base of a
CFL bulb where there is usually a small circuit housed inside. This may even
vary for each manufacturer.
2 things I haven't pinned down yet:
What is the normal amount of heat generated by the ballast of CFLs?
Is ballast heat included on the CFL wattage rating?
I have heard some CFLs have warnings they should not be used inside enclosed
fixtures (open fixtures only), and others warn against using them mounted
upside down. I assume this is due to ballast heat. But I could be wrong.
73, de ed -K0iL
-----Original Message-----
From: RFI [mailto:rfi-bounces@contesting.com] On Behalf Of Charlie Gallo
Sent: Monday, August 11, 2014 1:05 PM
To: Peter Laws
Cc: rfi@contesting.com
Subject: Re: [RFI] Cree LED Light Bulb
On 8/11/2014 Peter Laws wrote:
> On Mon, Aug 11, 2014 at 10:25 AM, Kim Elmore <cw_de_n5op@sbcglobal.net> wrote:
>> That's interesting as in their on-line FAQ, Cree says they approve of
>> installation in can fixtures. We've had 42 W CFLs in there for the last 8
>> years and never seen evidence of overheating. However, the light is cycled a
>> lot and I suspect the failures we've seen are related to that. Cree again
>> states that power cycling is harmless to their LED bulb. I guess I'll get to
>> find out!
> Lumens, gentlemen, please! IMHO, bulbs should also receive a rating
> based on how much heat they generate. Clearly, there is a difference
> in the heat output of an Edison bulb that consumes 60 W of power and a
> CFL that puts out the equivalent light (at considerably less power
> consumption).
Actually, we know this:
The TYPICAL 60 Watt soft white edison bulb generates 800 lumens. Now,
if there was 100% luminous efficiency, you get 683 lm/W, so you are
getting 1.17 watts of actual light, and 58.83 watts of heat
The cree bulb I have sitting here, which claims 75 watt equivalent and
800 lumens..(Interesting, eh) draws 14 watts
Again, you're looking at 1.17 watts of light, and therefore 12.83
watts as heat
Pretty much, if you think about any lightbulb, assuming it isn't
giving off massive RF, or sound, anything not out the front as light
is going to be heat
--
73 de KG2V - Charles Gallo
Quality Custom Machine-shop work for the radio amateur (sm)
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