Wrestling with power supply options, please advise

I have two choices: an easy 3-wire or a difficult 4-wire, cost would be about the same.

1) I have a 3 prong dryer outlet 15 feet from my brew station. I can use a spa panel to convert to 4 lead. Quick, easy, and 30A will cover my needs.

2) I used to have a spa, and one of the artifacts of that spa is an 40 foot run of 4 lead cable with a non-GFI 50A breaker. I can salvage that cable and re-run it to my desired brewing location (a big job), then wire into a spa panel.

Two disadvantages to option #2: relocating the cable will take half a day, and I might want to install a spa again someday.

The question:
Since the 3-wire dryer source will still use a shared ground/neutral, does the spa/GFI essentially provide the same safety as a 4 lead GFI set up?

I’m willing to tolerate the two disadvantages of option #2 as long as there is notable additional safety by using the 4 lead over the 3 lead.

Thanks a bunch…

Everything down-stream of the GFI spa panel is protected. The reason for the forth (neutral) wire is so you can run 120 V GFI protected appliances using the same main feed. The GFI will compare the sum of the two hot legs to the neutral leg to see if there is current leakage in the system. Without the neutral, you can only run 220 V appliances since any other neutral source will cause current leakage and the GFI to trip. Everything in front of the spa panel can be three wire since the neutral and ground are bonded in the spa panel (and main breaker panel for that matter).

That's not a very good explanation (P-J and others can explain much better than I), but you're just as safe using the two conductor dryer plug as you are the three conductor lead so long as the GFI is upstream of everything that you are touching/using.

Awesome, thanks for the help.

Right next to my brew station is a 110V GFI currently installed. So my needs are only for the 220V 30A.

Cheers!