We have installed a electrical box on the home that houses a 20 amp fuse w:gfi off the meter, then ran the wires to a outdoor box w: a gfi plug & a on/off switch. Seems to be wired correctly, but the 20 amp fuse keeps tripping. Thank You in Advance for any help, Michael

Either it is not wired correctly or there is a short, such as a pinched wire or some other damage. All I can offer beyond this is to shut the circuit off, disconnect the wiring, and re-connect it one set of wires at a time, and turn the power back on for each set to find the location that is tripping the circuit.

I will say I am a bit confused by the devices you state, meter, fuse, GFI, wiring, GFI, and switch. Why two GFI in one line? Are the GFI outlets or breakers? When do the fuses open? Why are you tapped into the meter? Is this 120 volts or 240?

Really need more detail to help further. Pictures would be great.