The current path in an electric chair is from a scalp electrode to a calf electrode. The current is therefore passing the brain and the brain stem, the lung and the heart. It is believed that the person becomes unconscious immediately after current onset, but it is well known that death is not immediate. The electric chair was used for the first time in 1890, and the first jolt was with 1400 V 60 Hz applied for 17 seconds, which proved insufficient.
Source: wiktionary