CFLs vs incandescent "max wattage" cautions in overhead fixtures....

Page 4 of 4  
ropeyarn wrote:

No. You are not exceeding the limits of either current draw or heat generally speaking. Now a CFL will produce some heat, but not nearly as much as a comparable output incandescent.
nate
--
replace "roosters" with "cox" to reply.
http://members.cox.net/njnagel
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
wrote:

You don't say if these are recessed fixtures.
If they are be aware that CFL life when operated base up in recessed fixtures can be shortened. Most of the cheap CFLs are designed to be base down (or sideways) and in open fixtures. The higher you go in wattage the greater the problem is likely to be. The issue is that the electronics, which are in the base of the CFL, are affected by the higher temperature when operated base up in enclosed fixtures. Even though the overall temperature is much lower than when a regular bulb is used, the electronics are more sensitive to it.
The Osram Dura One bulbs are specifically rated for base up use in recessed fixtures but are quite pricey compared to bargain CFL's.
Paul F.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Paul Franklin wrote:

Not recessed.......base horizontal...
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Closed fixtures - those without good airflow around the bulb, can cause overheating, and resulting shortened life.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

I have one data point of experimentation indicating that a 42 watt CFL produces slightly more non-radiant heat than a 60 watt incandescent. Therefore, it appears to me that CFLs of wattage much lower than 42 watts will not overheat fixtures rated for 60 watt incandescents. This means that CFLs of wattage up to low 30's should be OK, and those tend to outshine 100 watt incandescents.
Meanwhile, CFLs can overheat in some fixtures. My experience is that ones over 23 watts have a significant rate of overheating in downlights. 23 watt CFLs tend to be "lowish 100 watt" incandescent equivalence, usually outshining 75 watt incandescents.
You may ask - how could a CFL be more efficient than an incandescent at producing both light and non-radiant heat? The answer is that the CFL produces much less infrared than an incandescent does, especially much less in the 700-2500 nm range.
- Don Klipstein ( snipped-for-privacy@misty.com)
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
snipped-for-privacy@invalid.com wrote:

Make that mid or upper 30's or so. I did once measure temperatures on a fixture (with a non-contact thermometer) and got the fixture slightly hotter with a 42 watt (150 watt incandescent equivalent) CFL than with a 60 watt incandescent. Incandescents produce a lot of infrared - much to most of which escapes the fixture and becomes heat where it is absorbed - usually mostly all over the room it is in. CFLs produce conducted/convected heat more than anything else, and after that visible light.

If rated honestly, about 200-250.

Make that 42 watts. A 42 watt CFL typically produces 2600 lumens. A 150 watt 120V 750-hour incandescent of "Big 3" brand and with CC-8 style filament (axial coiled-coil) typically produces 2980 lumens, maybe more like 2900 even for "soft white".

As I said above, when I compared fixture heating by a 42 watt CFL and by a 60 watt incandescent, the fixture got slightly hotter with the 42 watt CFL.
Next lower common wattage I have seen is 30 watts, and I see those at Lowes. Home Depot may have 30 waters also. My experience is that those outshine 100 watt incandescents rated 1750 lumens by a small amount when young and at favorable temperature. I suspect they fade to close to 1670-1750 lumens after 2 or 3 thousand operating hours. I suspect they easily overheat in downlights and small enclosed fixtures.
Next lower common wattage of CFLs after that is 26 watts - usually rated to produce 1750 lumens - when in a favorable range of temperature and young. They typically produce something like 10% less after aging 2 or 3 thousand hours. 100 watt 120V incandescents of "Big 3" brand and CC-8 style filament are typically rated to produce 1670-1750 lumens.
Next lower common wattage of CFLs is 23 watts - usually rated to produce 1600 lumens. That is when in a favorable temperature range and in first few hundred hours of operation. I would say more like mid-1400's after aging 2-3 thousand hours and in a favorable temperature range - I would call that "roughly halfway from 75 watt equivalent to 100 watt equivalent". 23 watts is the highest wattage of CFLs that appears to me to have "fairly good" survival in downlights and enclosed fixtures. Philips "triple arch" "Marathon"/"SLS" 23 watt non-dimmable is the highest wattage and brightest CFL that I am aware of that is actually rated to take the heat of recessed ceiling fixtures. The dimmable 23 watt and the 25 watt versions of this one are not rated for this as of last time I checked.
- Don Klipstein ( snipped-for-privacy@misty.com)
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Related Threads

    HomeOwnersHub.com is a website for homeowners and building and maintenance pros. It is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.