My coworker swears by the Cree. Apparently they're bright and pretty close to incandescent coloring.

Rates where I live are .2544/kWh, one of the highest in the US.

Years back I swapped all bulbs I could to CFL and converted many to 12v. Now I'm looking into LED. But, like already mentioned, they are expensive. Costco is starting to carry a few now and I pick up a couple boxes each time I go through the store.

Some CFL light immediately. I did not know this at first and ended up buying them twice. Again, go to Costco to get the ones that light immediately. I find they do put out bright, near 4300K light. You just have to look for them.

One concerning point with CFL, is that they are very dangerous if you happen to break one and then step on them. We had a safety bulletin go out at work with pictures. Very gruesome. Be careful changed them, and if they bind on you, don't just grit your teeth and keep turning. Get some gloves and eye protection. And whatever you do, never step on one. You might just have to amputate your foot - no exaggeration.

Cree makes the best LEDs in the market by quite a margin. A lot has to do with reliability.

Resurrecting an old thread to ask a couple of questions about LEDs:

LEDs consume less power and create less heat. So, does anyone know why:

1- LED bulbs are built like they have huge heat sinks?

2- I can never seem to find 100W replacement bulbs? They always seem to be 40~60 watt replacements...with the occasional 75 watt replacement. I have many locations where I'd like to have 100 watt-equivalent bulbs on a dimmer, to allow brightness for tasks and dimming for normal or mood lighting.

Probably because the electronics associated produce a lot of heat.

Is there a built in transformer?

More than meets the eye!

Mark, I am not an expert but believe the extra parts behind the bulb are both transformer and heat sink as LED's radiate the little heat they produce backwards. I did some Google searching, here's a site that had a bit of useful information.

Also because of this thread I have started slowly replacing my halogen potlights with LED's. My strategy is mostly to wait for the GU-10 halogen to burn out and replace with an LED. I actually find I prefer the LED light better than the halogen anyway. I have been buying the Philips LED replacement from Home Depot which I believe is just re-badged Cree.

Speaking of heat, I had one of those curly lights go out on me last week. Normally they are very low heat. When this thing went out, there was a spot on it (where the light is emitted, but near the base) that got very hot to the touch.

Mark, its the way that an LED functions on the atomic level. A traditional light, generates light from heating the tungston to a ridiculous temperature, hence the reason they use tungston... LED's are a much more eloquent (scientific) way of generating light.....

When i was in school for electrical stuff, we spent a large amount of time on Diodes, which included LED's.. However, i do not remember the best way to explain it to you, so you will have to do some reading.. I found these two articles. They are pretty good, the second one seemed to go a bit more in-depth (i did not "read" the entire articles, i skimmed them for content)

http://electronics.howstuffworks.com/led2.htm
http://www.todayifoundout.com/index.php/2010/03/how-an-led-works/