Metropolitan Magistrate Jitendra Pratap Singh allowed the police custody of accused Manoj Jain, 49, who was arrested on January 21 in connection with the fire tragedy which took place on January 20.
A probe revealed it was a factory of "cold firecrackers" used in stage shows and Holi celebrations, the police had said.
The fire had started in the storage unit on the ground floor of the two-storey building and ripped through the structure. Of the 17 killed, ten were women. A man and woman were also injured.