<a href=showthread.php?s=&postid=15415892#post15415892 target=_blank>Originally posted</a> by DarG
The DE lamps require the glass shield because their glass envelope does not filter the UV. Actually some of the DE lamps do have UV inhibiting glass but they are all rated for enclosed fixtures (meaning they still require the glass shield) only regardless.
The glass evelope of the Mogul lamps on the other hand does inhibit the UV so no shield is required to do so.
If you are asking about Mogul lamps only ... I do use the glass anyway, to keep the reflectors from salt spray and as a safety feature preventing potential splash on the lamps and socket.