The court extended the police custody of Manoj Jain, who was produced before the court on expiry of his five-day remand, till January 31.
The other accused and co-owner of the firecracker unit, Lalit Goyal, would also be produced before the court on the same day.
Jain was arrested on January 21, while Goyal was arrested on January 27 and sent to four-day police custody.
While seeking Jain's two-day custody, the investigating officer submitted that the accused was not cooperating in the interrogation and pretended to be ill frequently.
It further submitted that a detailed investigation could not be conducted due to shortage of staff as the force was busy in arrangements of Republic Day parade.
The court, while allowing the police's plea, directed it to conduct the accused's medical examination every 24 hours till he was in custody.
Meanwhile, advocate Rishipal Singh, representing few victims of the tragedy, moved an application seeking an independent probe into the matter by agencies like the National Investigation Agency (NIA), Central Bureau of Investigation (CBI) or the Anti-Terrorism Squad (ATS).
The plea sought transfer of the probe from Delhi Police Crime Branch, alleging that "no fruitful investigation" had been made so far.
"Till date, no investigation has been carried out despite the lapse of more than 8 days from the date of registration of FIR," the plea said.
A fire had broken out in the storage unit on the ground floor of the two-storey building in Bawana on January 20 and ripped through the structure. Of the 17 killed, 10 were women.
A man and woman were injured in the incident.
The court had last week dismissed the anticipatory bail plea of Goyal saying the allegations against him were "serious".
It was earlier informed that both the accused were running the factory without any licence and the explosive materials were procured from outside Delhi.
The probe agency had claimed that the explosive materials were brought to the city without any permission or checking, and sought the custody of the accused to verify whether he was running any other such illegal enterprises.
An FIR was registered under various provisions of the IPC relating to culpable homicide not amounting to murder and negligent conduct with respect to fire or combustible material.
The maximum punishment for the offences is 10 years.