How do you reset an outside 240V AC condenser breaker box with a black plastic T handle marked ON OFF?
This is pullout disconnect switch. Pull out on the "T" handle to disconnect the circuit. If the word ON is right side up and reinserted the circuit is made. If the work OFF is right side up and reinserted the circuit is off. Some disconnects are fused, they have two cartridge fuses under the cover beneath the pull out. These may need to be replaced if power is not reestablished.