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· Registered
379 Posts
Discussion Starter · #1 ·
I am installing lights in my basement, quite a few, and I figured blindly that since I was doing LED's on the 18 recessed lights that I'd be fine on the dimmer and I tonight while doing the install realized I'm over the rated wattage for LED's on the dimmer (150) but well under the incandescent limit (600), I can understand there is some limit and that if I snap off the heat sinks it has that I lower the limit but I'm not sure I quite understand what is driving the LED/CFL rating to be lower. Any ideas?

· Electrician
39 Posts
I'm sure someone will correct me, but here goes.....

CFL's and LED's use a power supply to change the voltage amount (i.e. 120V to 48V), type (AC to DC), and sometimes other things like frequency in order to light the diode (the "D" in LED) or gas in the CFL properly.

This power supply is sometimes located in the lamp itself, or remotely, depending on the installation.

Regular plain old incandescent lamps are just a filament sealed with an inert gas inside a glass bulb.

Incandescent lamps are simply a resistive load and the wattage can easily be calculated when using a dimmer. While there is no set in stone rule, I generally try to stay at about 80% of a dimmer's capacity when designing lighting. Dimmers tend to get hot when you approach their wattage threshold.

Now with CFL and LED power supplies, while the actual power consumed is less, the way they transform the electricity can put strain on a dimmer. They are prone to high inrush currents (a whole lot of current all at once when the lights are turned on) and repetitive current spikes (the current used suddenly increasing then going back to normal).

For these and other reasons, dual rated dimmers will have two wattage ratings, the low one being for CFL/LED.

I hope this helps.......
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