It will never work, no matter how long you let it 'warm up'..
You need a ballast for that bulb.
psteve Reviewed by psteve on . 50W HPS Bulb Wont Work I Have a 50W HPS Bulb and i was wonder if it would work in a Reg. Lamp i was wondering if i had to let it warm up for awhile or somethin Is There anyway i can get it to turn on with the normal household lamps and power???? heres a link to a website of the bulb LU50/MED | C50S68/M | 50W HPS Bulb Medium Base Clear - ProLighting.com Rating: 5