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Joined: Nov 2007
Posts: 763
K
KJay Offline OP
Member
Ive been using CFL bulbs in the ceiling light fixtures of my own home for a few years now and Im noticing some discoloration and degradation of the fixture wire insulation, white paint on the canopies and the plastic lamp sockets. Im guessing this is due to the heat and UV light from the fluorescent bulbs.
Years back, I remember a similar type of yellowing and degradation of the white plastic housings, wire insulation and internal components of incandescent exit lighting that were retrofitted with fluorescent lamp kits.

Have you seen this type of thing occurring in incandescent fixtures using CFL bulbs or that have been retrofitted with fluorescent lamp kits?
Im wondering how this will play out if and when the proposed incandescent bulb ban takes place. It seems you would have no option but to use CFL bulbs in fixtures that were never designed, tested or listed for their use, which could result in various forms of deterioration on a large scale that Ive been noticing.
I find it interesting that as electricians, we have to go to great lengths to follow UL listings and manufacturers instructions, for fear of liability, but Congress seems poised to pass a law which mandates the complete dismissal of these.

Joined: Jun 2006
Posts: 613
M
Member
Where is the heat? That is where the problems will be, The heat in flourescent luminaires moves from the lamps to the sockets and the ballast.

I am seeing more and more problems with ballasts causing heating problems including the complete decomposition of plastic fixture boxes.

An incandescent bulb is hot above the base. IE you unscrew a hot bulb and you can often hold the base but the glass burns your fingers. CFL are the oposite as are PL lamps which also have a heat producing ballast which transmits its heat into the outlet box. Lots of the new energy efficient luminaires are reworked incandescent luminaires.

Joined: Jan 2005
Posts: 5,316
Cat Servant
Member
I'll disagree a wee bit.

It's not heat at all ... after all, there is no part of a CFL that gets anywhere near as hot as an incandescent.

UV from the bulb is another issue. Ever wonder why troffer lenses get so brittle? Or why the nice ones are so 'rubbery' and cost so much more than the box-store specials? It's all about the UV.

The UV component of fluorescent lighting plays pure hell with plastics - and is likely part of the reason some folks just don't like fluorescents.

Joined: Jul 2004
Posts: 783
L
Member
Reno, I'll disagree with you. smile

The UV created by the flourescent bulb is used to excite the phosphor inside the bulb. I would expect that little to no UV escapes the tube under normal operation. Plus glass is not transparent to UV. However, quartz is transparent to UV. That is why quartz halogen bulbs have to have a glass filter to block the UV. That is also why metal vapor lamps have a separate glass bulb around the arc bulb, to block UV.

I expecxt the reason why box store fixtures have such crappy diffusers are because it is cheaper.

Joined: Jan 2005
Posts: 5,316
Cat Servant
Member
Larry, I agree with you to a point ... yet ....

Even quality fixtures used in commercial applications have their diffusers yellow and become brittle with time.

Drapes and upholstery still fade in the sun, even when there's a double-pane window in the path.

Isuppose we can compare lighting to sex: both intensity and frequency matter! laugh

Joined: Jun 2006
Posts: 613
M
Member
Reno
I agree the ballast isn't likely as hot as a bulb but the ballast is sinked to the base of a luminaire and if the luminaire is surface mounted right on the box then the box becomes part of that heat sink. Some of the luminaires i am thinking of have glass lenses and the ballasts are not visible to the radiated light.
CFL have the ballast built into the base and scerw into normal 660 watt lamb bases. If a 100 wat bulb was installed the heat is produced above the base in the filament and yes it is damn hot. The bulb base is relatively cool and depending on how long the luminaire has bee on will get close to the internal ambient or the luminaire.
Replace that 100 watt bulb with a 27 watt CFL and the interior of the luminaire won't get anywhere near as hot except that the base gets hottest and it gets hot much sooner than the base of the incandescent bulb. Like I said it is pretty easy to hold a CFL by the glass even when it has been on for a long time. The base is hot to the touch and very hard to hold if it has been on for a while.

Joined: Apr 2002
Posts: 7,279
Likes: 3
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Refering to the 'screw-in' CFL bulbs, nobody has mentioned the orientation of the base within the luminaire.

Years back, Phillips came out with the 'Earth Light' CFL, and the directions on that box read....burn base DOWN only. The recent 13 watt that was a give-away at the mall, does not seem to have any direct guidance (directions) on compatability.

The real fine print, on the inside of the box, in three languages mentions 'use in recessed fixtures will result in shorter bulb life'. Further down, 'base of unit is hot after operation'.

I saw quite a few of the early Earth lights' that suffered from discoloration of the base containing the ballast, and some with what appeared to be ballast failure and very dark brown plastic bases.

A side note on this subject was a discussion with an Architect relating to CFL fixtures. He spec'd CFL recess, but no brand name or model. The Ec installed regular H-7 cans with screw in CFL bulbs! I'm still waiting for a response from the H-7 mfg if this could be a listing issue. BTW, open trims I assume. This could just be an Arch/EC issue depending on the mfg info.

As KJay was alluding to, there may be an awful lot of degraded sockets from the CFLs in the future.





John
Joined: Jan 2005
Posts: 5,316
Cat Servant
Member
It's not a listing issue.

UL has issued a blanket statement, published in IAEI news, that pretty much says 'if it fits, it's fine.' The only qualifiers relate to markings on the bulb - not the fixture.

Joined: Mar 2007
Posts: 404
Member
Originally Posted by LarryC
The UV created by the flourescent bulb is used to excite the phosphor inside the bulb. I would expect that little to no UV escapes the tube under normal operation. Plus glass is not transparent to UV. However, quartz is transparent to UV. That is why quartz halogen bulbs have to have a glass filter to block the UV. That is also why metal vapor lamps have a separate glass bulb around the arc bulb, to block UV.


Regular glass is partially transparent to UV, and I wouldn't count on a 100% efficient phosphor and completely uniform coating along the inside of the envelope. Difference in heat can easily be measured with an IR thermometer, and the inherent increased efficiency of the fluorescent system (lower wattage, more energy converted into light) logically suggests a lower heat output. What other factor, besides UV, would break down the plastic so much? If you have a look at some exit signs, the fluorescent ones fall apart much quicker than incandescent or UV... I've broken a couple of covers on fluorescent ones because the plastic became so brittle from burning 24/7.

I'd like to see your source for claiming that quartz-halogen bulbs MUST have a glass filter. Other than PAR and sealed MR-type lamps, a lot of QH lamps have no such filter. Especially with MR16s and PARs, I think the reason for having a sealed unit is more for protection of the fragile envelope from moisture and debris, and to contain the fragments if/when the lamp blows.

Depending on the type of enclosed fixture we're taking about, have a look at LED PAR/MR lamps. While LEDs probably won't replace our general workhorse bulb, they are great for directional lighting--and the latest batch have color temperatures in the range of halogen.

Joined: Jul 2004
Posts: 783
L
Member
Noderaser, I do not have a chapter and verse citation for the need for glass.

A quick search found this document from NEMA.

Quartz halogen bulb safety

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