This GE Form 400 shown here is not your typical Form 400 luminaire. Those who are experts at detecting different streetlight models will notice that this particular luminaire has a longer slipfitter than regular Form 400s, but still shorter than the intergrally ballasted Form 400. I have wondered about why this one had the longer slipfitter, then I figured out that they actually have recessed sockets that allow 700-1000 watt mercury vapor lamps to fit in, thus the reason for the longer slipfitters. The regular Form 400s with short slipfitters can only take lamps up to the ED-37/BT-37 size, which is the typical size used for 400 watt lamps. The heads themselves are exactly the same size. I have thought they were called Form 402s because a 402 can take 1000 watt lamps, but they turn out to not be 402s, since a real Form 402 is actually larger than a Form 400, physically.
The above light was mounted on the side of a grocery store, and the lot had 8 of them alltogther. This photo was taken sometime in mid 2002, but unfortunately during Feburary/March 2003 all these lights were replaced by Lithonia CH 120s (formerly T&B/AE Series 125), 400 watt HPS full cutoff. There is still a large shopping center in San Jose that has some of those lights around, and some of them still have clear 1000 watt mercury lamps in them.
