TNEB slab rates for Residential services with free 100 units:
TNEB Slab Rate Domestic Houses


No of units

Rate (Rs.)

1100

1

1200

1.5

1200

2

201500

3

1200

3.5

201500

4.6

501 & Above

6.6

 If you consumed below 100 units, then you fall under first slab which charges 1 Rs per unit. Based on the promise given by ADMK government during the election time, the first 100 units are free. So you DONT need to pay for upto 100 units power consumed.
 If you consumed above 100 but below 200 units, then you fall under second slab in which 1 unit costs 1.5 Rupees. You can reduce first 100 units as concession.
 If you consumed above 200 but below 500 units, then you fall under third slab in which first 200 units costs 2 rupees and next 300 units costs 3 rupees. You can reduce first 100 units as concession.
 If you consumed above 500 units, then you fall under final slab in which first 200 units costs 3.5 Rupees , next 300 units costs 4.6 Rs per unit and further units costs 6.6 Rupees per unit.