The 5.5 inch domes do not dissipate as much heat as the larger diameter domes. That is why they are rated for lower wattage bulbs compared to the larger domes.

My advice is to not use a 100 Watt bulb in any 5.5 inch dome if at all possible. The 8.5 inch dome is a much better choice above 75 Watts.

I do not think 220 deg F will cause a fire, but that is very hot to the touch. 160 deg is much much better.
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Mark