Section 7(4)(i) in Tamil Nadu Electricity Grid Code, 2005
(i)Power drawing entities shall endeavor to restrict their net drawal from the Grid to within their respective drawal schedules whenever the system frequency is below 49.5 Hz. When the frequency falls below 49.0 Hz., requisite load shedding (manual) shall be carried out to curtail the over drawal. Such load shedding shall be pre-planned for each level of under frequency.