Those are part of the heat sink to prevent the dimmer from failing from overheating if used at its full rating. They still work when the plate is installed since the top and bottom are still open and function to provide a chimney effect.
Is the protruding heat sink necessary?
The reason I am asking, is I am trying to reconfigure my wiring a little.
Right now in the living room, I have three sets of lights:
LEFT: 4 soffit recessed lights (75W max each)
MIDDLE: 7 lights (60W max each)
RIGHT: 4 soffit recessed lights (75W max each)
Right now, the LEFT and RIGHT lights are controlled by two switches in a two gang box, where the LEFT lights are controlled by the switch on the right, and the RIGHT lights are controlled by the switch to the left. Then to the right of the two gang box is a single gang box with this 1000W dimmer with the heat sink fins.
I would like to put in a three gang box, where the left switch controls the left lights, the middle switch controls the middle sets of lights, and the right switch controls the right lights.
In this case the middle switch cannot be this 81000-w dimmer since it sticks out very far and I need to use a three gang decora wall plate.
I am thinking of going with the Lutron DIVA DV-10P dimmer switch for the middle set of lights.
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It is rated for 1000W as well but it does not have the thick protruding fins. It has some fins on the sides, but since it is going in the middle of the 3 gang box I will have to remove the fins on each side. The specifications stated that for a 3 gang box it will be derated from 1000W to 650W, I assume that means with the two sides removed?
I have in the middle the 7 lights 60W max each so it's 420W under the 650W, on top of that I will be using LED bulbs which use only 5W each. That should work right?
The Lutron 10P dimmer is for incandescent lights only. You can't use it with LED bulbs. If you use it with 7 x 60W incandescent bulbs, your 420W total will be under the 650W no-fin de-rated spec.
Many LED bulbs don't get along very well with dimmers and many dimmers don't work well with all LED bulbs.The fixtures are all old incandescent fixtures from the 1970s. If I intend to put in dimmable LED bulbs, what would be a good decora style preset dimmer to use if 99.9% once I dimmed it to where I want it the first time I never ever change it I just use the on/off switch from there forward? Or is it better I just use a regular switch and forget about using dimmers altogether and go with the cheaper non-dimmable bulbs since I have three sets of lights I can control (kind of) by using one, two or three sets of lights?