Lamp Wattage

[Metspitzer]

I have a metal, clamp-on, desk lamp with a swivel head. Today the compact fluorescent lamp burned out. I bought some new 100 watt (equivalent) replacements because it is a reading lamp. On the package, it says 23 watts.

I plugged in the new lamp and "Voila"! Up and running! Within an hour, the new replacement flickered and went very dim. I switched off the lamp and removed the bulb. It was hot, but not too hot that I couldn't take it out right away with my naked hand.

I checked the wattage rating of the lamp. It says..........40 Watt Type A or smaller lamp. Looking at the package, I don't see a type, but I bet it is not type A.

I assume the lamp has some kind of thermal protection. The existing lamp was a compact fluorescent that had been in there for a few years. After the lamp had cooled down, I put (from another lamp) the same type that had been in it for years. That one worked. I did notice that the old type are 27 watt and the new ones are 23 watt, but the new one only worked for an hour.

After checking all the lamps, the original bulb is bad, but the new replacement still works. I am now using a old 27 watt that was exactly like the burned out one. I have switched the new 23 watt to a free standing lamp that is on a night stand. (It is working fine too)

Anyone have the info on whether compacts can/should be used in fixtures with Type A spec? Shouldn't the bulb be rated (for heat) at

25 watts even though it is a 100 watt equivalent?

Pictures enclosed. (My hands shake, so these are the best photos I could get.

It is hard to tell where any thermal protection would be in the lamp.

[micky]

How do you know you didn't just get a bad bulb?

Type A iiuc is just any bulb with the standard full size screw in base. If it screwed in, it's type a.

There's barely any difference between 23 watts and 27 watts and they're both lower than 40 watts, which is what the lamp will handle.

100 watt equivalent is just a measure of the amount of light it makes (as much as a 100 watt incandescent) and a high number doesn't mean the lamp can't handle it. It's only the heat that is a problem for the lamp. and CFLs are cooler than even a 40 watt incandescent, I think. (But I don't know exactly how hot they get because I avoid touching them because I have confused them with halogen lights or something. Is there any reason not to touch the glass of a CFL?) .

Looking down the cone of the lamp, it's clear to me that the wire goes straight to the light socket and there is no thermal protection. Almost all lamps have none. If it gets too hot, it will shorten the life of the plastic parts. I'm sure the socket itself and the cord and plug can carry well over 40 watts, probably 150, but the shade might melt or get brittle if plastic, or conceivably hot enough to hurt when one's arm touches it if metal.

[micky]

To amend my own post.

I don't think the shade will melt with say a 75 watt incandescent bulb, and by plastic get brittle, I meant, over time, months or years.

As to hot, the shade will never get hotter than the bulb itself, I think.

[Metspitzer]

I know it is not a bad bulb because I put it in a table lamp and it works fine. I left the table lamp on for over an hour just to see if anything happened. I didn't expect anything to happen with it in the table lamp because there is lots more room for surrounding air to dissipate the heat.

I may put it back in the desk lamp to just see if it will overheat again. (If it was overheat)

[Metspitzer]

Why would it say type A or smaller? If the base was type A, anything smaller wouldn't work. It has to mean the shape of the bulb.

[Robert Green]

Desk lamps designed for incandescents are designed to dissipate the bulb heat through convection. CFL's heat up at the base and the size of the electronics pod can block the cooling vents found in most lamps causing them to overheat. That could cause any thermal protection in the CFL bulb to kick in.

Is there any substantial difference in the shape of the bases of the CFL's that you have been swapping? I didn't see any pictures of the various bulbs you have tried.

Another potential cause of intermittent behavior is that the CFL bulb does not screw into the socket fully and makes poor contact. When it heats up enough, thermal expansion can cause the contact to break.

[hrhofmann]

Put the intermittently bad bulb back in the fixture in which it failed, and turn the fixture so that the heat generated in the blob at the base of the bulb can vent its heat upward and outward, rather than being trapped in th e base of the lamp fixture. Turn the lamp on. Bet the lamp runs forever ( almost).

[dadiOH]

Nope.

[trader4]

nd turn the fixture so that the heat generated in the blob at the base of t he bulb can vent its heat upward and outward, rather than being trapped in the base of the lamp fixture. Turn the lamp on. Bet the lamp runs forever (almost).

That would be a good test. He's already found another older CFL that works, otherwise I'd say to try another brand. There has always been considerable variation from one brand to another. Another brand could be more tolerant of heat.

Another example of why some of us didn't want the govt forcing this stuff on us instead of letting people make their own choice regarding CFL vs incandescent.

[clare]

SOME CFL and SOME LED lamps have internal temperature issues - whether intentionally or by poor design the shut down when they get hot. Many say "not for use in totally enclosed or recessed fixtures" or something similar - and they either shut down or blow out if they are not ventilated properly and get too warm.

What is too warm, you ask?? Warm enough to shut the light down - for some that might be as low as

108F., +/1

[clare]

From wikipedia: The A-series light bulb is the "classic" type of light bulb that has been the most commonly used type for general-purpose lighting applications since the early 20th century. It has a pear-like shape and an Edison screw base. The number that follows the "A" within the A series indicates the width of the bulb in one-eighth inch units.

The most commonly used A-series light bulb type is the A19 bulb, which is 2 3/8 inches wide at its widest point, approximately 4 3/8 inches in length, and has a one-inch wide (type E26, i.e. approximately 26 millimetres wide) Edison screw base.

Although most A-series bulbs have historically used incandescent lighting technology, some other technologies have been used in A-series bulbs more recently ? such as LED lamps.

Type A or smaller would mean no "fat albert" or "globe" style bulbs, You could use a type S, P, or MB bulb, but not a G, E ER, or PAR bulb

[clare]

He is right. It is the shape of the bulb, not the base - although MOST Type A bulbs are either e26 o E27 base, they CAN be DC or DC pt bases, or DC Bay, or SC Bay base. It is the envelope shape that makes it a type A bulb. It is the pear shaped evnvelope - and the number after the A tells the size in 1/8 inch increments. An a24 would be 3 inches in diameter, an A21 would be

2 5/8 inches in diameter.

[Tony Hwang]

Hi, I did some experiments in the past on this heat issue. Depending on what bulb was in the fixture some type(wrong type) burnt out in days. Some even popped a hole on the glass envelope(due to excess heat), etc. So heat dissipation is the matter, IMO.

[micky]

Where the OP used the term "lamp" I would have used "bulb". So when he asked about thermal protection in the lamp, I thought he was talking about the thing that plugs into the wall and has a bulb screwed into it. And this one has no thermal protection. But the bulbs in question may well have it, especially since people here say they do. ;-)

I know that bulbs are called lamps in some cases, but I didn't expect it here.

[pilgrim]

This means that your new CFL bulb is rated (for heat) at 23 watts even though it is a 100 watt equivalent bulb. Later on you mention 27 watt bulbs. This is not enough difference in wattage to make a difference. Either bulb will work just fine in a 40 watt lamp.

Your lamps and your CFL bulbs are all type A. Type A lamps and bulbs are common old every day lamps and bulbs with ordinary-sized shrew-in bases.

No. Your lamp has no thermal protection. Your new CFL bulb may have thermal protection, but your lamp does not.

You say that you put a CFL bulb (from another lamp) into your desk lamp and that this bulb worked. This indicates that your desk lamp is OK.

Also, you switched the new 23 watt CFL bulb to another lamp and "it is working fine too". This indicates that your new CFL bulb is OK.

Is it possible that your new CFL bulb was not screwed into your desk lamp firmly enough?

Is everything still working OK? If so, there's a good chance that when you switched the bulbs around you got the desk lamp bulb a little tighter in its socket and thus cured the problem.

Hope this helps.

[Metspitzer]

I agree with everything you said except for the bulb not being tight (I could be wrong, I frequently am). I haven't tested it yet, and may not, but I would guess it got too hot. It seems to me that the new 23 watt is more sensitive to heat (or gets hotter) than the old 27 watt.

[Pat]

In addition to what others have said, note that base up vs base down matters with some designs of bulbs. If it gets to hot in your clamp-on but your other lamp in which it works hold the bulb glass up, that could be the difference. (I didn't read every post in the thread, so my apologies if someone already said that).

Pat