I've had this nagging question which might sound stupid, but when a lighting fixture is rated for a given number of watts, does that take into account energy efficient bulbs?

For example, let's say you have a fixture that calls for 60W maximum bulbs. Is it acceptable to install one of those energy efficient bulbs that uses say 23W actual, but produces the equivelant of 100W of lighting? In other words, are you being limited by wattage or lighting output when a fixture calls for a given wattage? Is heat itself the issue, or is conductor size and material type the limiting factor with respect to fixture wattages... or both?

I can't seem to find anything code related in this area, and manufacturers don't seem to address it either.

So if a customer likes a certain light fixture that only uses maximum 60W bulbs, but it doesn't produce enough light for their tastes, can we sell them on using lower wattage, brighter energy efficient bulbs in the case?

This has been a nagging question everytime I see one of those stickers on fixtures.

Joe

Absolutely. The watt limits are determined entirely by surface temperatures; a 40 watt compact fluorescent might give off as much light as a 150 watt incandescent, but won't get any hotter than a 60 watt incandescent.

However .....

The fixture often is made just large enough for a 60 watt bulb to be used, and even a small CFL will have trouble fitting in.

Likewise, the CFL's put out a fair amount of UV, which is what causes the troffer lenses to become yellow and brittle. A CFL in an ordinary fixture will have a similar effect on any plastic.

All that matters is how much heat is produced, which in turn is how many watts it consumes.

Nobody cares how much darkness it consumes.

Did you know that a standard frosted incandescent lamp only emits 6% of it's input power as usable light?.
The other 94% is heat.
With figures like this, it should be a criminal offence to operate them.

LEDs are probably going to be the light of the future.

Drive down the road (or look in my upstairs window ) and you'll see that.

Ian A.

Two things to remember re this.

1. The vast majority of compact fluorescents have like a 0.5 power factor, so multiply the watts by 2 to get VA. (Not that this matters for heat dissipation.)

2. If it is a recess can, you can't hurt the fixture any by overlamping, but the CF lamp may burn out prematurely. Incandescent lamps give out much of their heat as IR, but the heat from CFs is mostly conductive. The electronics in some CFs can't handle being bottled up in a recess can. And I don't know if there are any that can handle being enclosed in a shower trim.


Maybe. The super-phenomenal efficiency that has been advertised for LEDs is based on comparing the output of 1-6 LEDs to very inefficient small incandescent lamps. As the lumens output increases, the efficiency advantage of LEDs decreases. It is practically impossible to beat LEDs for a task flashlight or nightlight, but scale it up to 900 lumens, and they are actually not much more efficient than an incandescent, and much more expensive. CF lamps are the most efficient for most applications.

My sister-in-law had a problem with her hair dryer tripping the breaker. Her condo was built about 1973. There was a 6-lamp fixture over the sink on the same 15A circuit. Since I had driven my car over there instead of my service truck, I just went to IKEA and bought 6 CF lamps for her. Problem solved.

And yes, I wholeheartedly endorse using CF lamps to sidestep the overlamping issue. I have mainly fluorescent in my own home, with a handful of halogens for task lighting.

I used to anger the GE gods when I worked there with my pronouncements that Thomas Edison didn't invent the incandescent light bulb, he invented an electric heater that lit up.

I don't have heat yet in my addition, but simply turning on all the lights has kept it surprisingly warm! 1300W worth of bulbs will do that, though.

If you are putting a CF in a can you should be using the reflector style. They are designed to radiate the heat down and out of the can. (like the incandecent).
I have heard arguments that the regular spiral CF should never be mounted base up.

If that's the case then just about the only lights fixtures we could use CF's would be Table lights. Where did you hear this?

I admit it is anecdotal but on usenet folks are trying to determine the cause of early end of life failures of CF lamps and they are usually in lampholders that hold the lamp base up. (cans, jelly jars etc)

I would not make too much of this "base up" stuff.

I have a few restaraunts as customers, and they all have CFL's in their cooking hoods. This is surely a location of elevated temps; being inside a "jelly jar" fixture makes sure it gets warm inside. The CFL's, according to my customers, far outlast conventional bulbs.

Likewise, I have a number of CFL's mounted horizontally, in open 'keyless' bases. Some CFL's last; others crap out inside a month.

I spoke with a man who has been in every factory (no kidding) that makes CFL's. His opinion of ALL of them is that they are pretty sloppy manufacturing facilities. I suspect that CFL failures are almost all due to poor quality control. You simply won't get the "beast and the brightest" when your manufacturing philosophy is "quickest and cheapest."

When I needed to light a friend's new workshop the big orange box didn't have the right trim for the amount of light I needed, especially since I needed an IC rating. So I went with a PAR 38 CFL lamp and made it bright enough. 27W versus 120W, doesn't trip the thermal cutout.

JJM,

What State are you in?

Typically, if you are figuring Loads on Branch Circuits, you would apply a Fixture's _MAXIMUM_ Wattage (if using Incandescent Lamps), and apply that Maximum rated Lamp Wattage as Volt-Amps (E x I or Watts = VA).

Example:
If the Fixture lists "100 Watt Lamp Maximum", then figure all of these type of Luminaires at 100 VA Each - regardless of the type / Wattage of Lamps installed.

If you are dealing with Fluorescent Fixtures (if CFL, only on Fixtures _WITHOUT_ Screwshells for Lamp Mounting), then ratings per Fixture corresponds to the Manufacturer's Specifications and Listed values.
Load VA may also be found on the Ballast.

Same goes for HID Lighting.

In a nutshell, if you are compiling data for Energy Conservation forms (or installing Lighting to comply with Energy Conservation Codes), the installed Wattage of a given Fixture is obtained from Manufacturer's Listings (look for "ANSI Watts" in cut-sheets).

Feel free to ask additional questions if needed.

Good luck.

Scott35

Cheap electronic dimmers and motion sensors will kill CF bulbs in a hurry, I know that much. Does everyone already take that into account, or do people out there keep plugging CF bulbs into occupancy-sensor-controlled fixtures and gripe when they die after a month?