GE LU400/XO/T/40 GE Lucalox 400w SON Lamp External Ignitor E40 Cap – GE 78739. A GE Lucalox 400w SON lamp with external ignitor. This lamp has a GES/E40 cap and is commonly used in commercial and industrial installations such as road, street and flood lighting. 2100k (extra warm white) They are suitable for use in both open and closed fixtures.