I'd be very interested to know if anyone has definitive advice on which types of light bulbs are considered an issur d'rabbanan (Rabbinic prohibition) vs an issur d'oraita (Torah prohibition) to turn on on Shabbat. This is a great discussion forum, and this is my first posting.
I've read various articles and asked some sheylot about it, but it seems the answer depends on technological issues, which themselves are not so clear cut.
The categories of light bulbs currently on the market are:
I understand that these are an issur d'oraita because of they involve heating a filament till it glows.
Apparently these are less of a problem than incandescent bulbs, but some compact fluorescent bulbs use a starter that requires a glowing filament.
The situation is complex because there are sub-types of CFL, including the following (see also the above link)
(1) instant-on; and (2) cold-cathode
The above 2 types may use a different filament (or no filament), so maybe they are less of an issue (or perhaps they still use a hot filament.. one really needs to be an expert in the technology to understand!).
In general, it seems that if a bulb does not reach 'yad soledes bo' temperature then it would not be a Torah prohibition? However, the average 60W equivalent compact fluorescent bulb gets too hot to touch, so is that a problem?
These should be less of a problem d'oraita, as they don't work by means of a glowing filament. However, they apparently can get very hot because the electronic circuit board that runs each bulb can generate a lot of heat, at least with the brighter types. Do they got so hot that they are a Torah prohibition?
Please correct me if my assumptions are wrong. I'd be very interested to hear any definitive views on this. Thanks!