what is the difference between bulb angle and bulb flat used in ship building

Please check it.It should be 240 X 12 if its is bulb angle.

Manjush Navale

To hold the light bulb at a vertical angle and stop it from falling off.

Yes, if you have exposure,even from a side angle at a fairly close distance it can give you a flash burn. I have had it happen to me with a 75watt incandescent bulb not properly shielded.

It all depends on the main area that you want the bulb or tube to light up. The best thing to use is a spotlight selector.