We report precise measurements of the thermoelectric power (TEP) of granular superconducting Bi 1.75 Pb 0.25 Ca 2 Sr 2 Cu 3 O 10. The TEP is strictly linear at high temperature. Superconductivity fluctuations set in at about 140 K. From the temperature derivative of the excess TEP (with respect to a straight line at “high temperature”), the critical behavior is obtained in the mean field regime, and is found identical to that of the temperature derivative of the excess electrical resistivity.