As Mr Wizard said, if it is your desire to use your 30 amp extension cord when you need a longer run to a 50 amp circuit, you will not be able to do this. The wires in the extension cord are too small and you will be 1 wire short. When you plug into 50 amp with the cord that came with the RV you will have all the power you need so there would be no need for a 2nd electrical run to the RV so if you are trying to do something else with that extension cord, please let us know. If you need a 50 amp extension cord I highly recommend you buy a 50 amp extension cord.
