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Re: [RFI] Cree LED Light Bulb

To: "'Charlie Gallo'" <Charlie@TheGallos.com>, Peter Laws <plaws0@gmail.com>
Subject: Re: [RFI] Cree LED Light Bulb
From: "EDWARDS, EDDIE J" <eedwards@oppd.com>
Date: Mon, 11 Aug 2014 19:25:06 +0000
List-post: <rfi@contesting.com">mailto:rfi@contesting.com>
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 

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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