A friend wants to install a 24000 BTU air conditioner in a VW repair shop with around 1920's wiring. He doesn't want to tamper with the old service panel.( I don't know what the service drop current rating is ). There are no240 volt outlets in the shop. He wants to provide 240 volt power to the air conditioner by plugging extension cords into two120 volt outlets from opposite phases of the service and wiring them to a 240 volt outlet for the air conditioner! He also wants to do this with his 240 volt, 6 hp compressor, which will probably be connected to the same branch circuits and that will surely blow fuses if both units are powered. From my experience, the old 120 volt outlet and lighting branch circuits have badly tarnished14AWG wiring, fused at 15 amps. He might buy a new 24000 BTU air conditioner rated at 240 volts, 12.5 amps. That's probably about 80% of the branch load rating. I cringe at the idea of using extension cords, because the plugs and sockets might overheat. I hope he uses time delay fuses for starting surge. He might be able to do it, at least for a while. I objected to this fire hazard and offered to install "code" branch circuits, charging for parts only, but he's not listening.