Jun 14, 2015 · Usually 100 and 150 watts are used for residential streets, 200, 250, and 400 for wider streets and freeways, and 1000 watts for the 100 foot towers on the freeways. The 1000 watt lamps are roughly 8 times as efficient as household incandescent. The initial HPS installations in the Twin Cities that I recall, from at least the 1970s, were I-35W