From about 1.3 million hadronic Z decays collected with the ALEPH Detector in 1992 and 1993 inclusive muons and electrons have been analysed to measure the semileptonic branching ratios for primary and cascade b decays. The analyses take advantage of the high purity b sample obtained using lifetime tagging. A fit to the P_perp spectra gives the preliminary results stat syst models BR(b->l) = 0.1101 +/- 0.0010 +/- 0.0021 +0.0024-0.0017 BR(b->c->l) = 0.0768 +/- 0.0018 +/- 0.0031 +0.0034-0.0043 The model dependence has been reduced by using charge correlations in the event rather than fits to the P_perp spectra. A preliminary value of stat syst models BR(b->l) = 0.1101 +/- 0.0023 +/- 0.0028 +/- 0.0011 has been obtained
