Realize I'm asking what requires some CSI or amperage / volt testing on site , but likely can get a number of opinions and then I'm going to call in a service guy to test everything right.

I bought a working (I saw it operating) Hot Springs Prodigy H that was set up 3 wire -115 and I rewired it for 230 (3 hot, 1 neutral, 1 ground) to a new outdoor cut-off box w/ new 20/30 A configuration. I switched the pin jumpers and the power jumpers as shown on the HOt Springs schematic. The main panel feed is 4 wire from a 55 Amp GFCI left over from our old Cal Spas 220V.

So I try and turn it all on in this order 1) Engage main panel 55 A GFCI 2) Engage cut-off panel 20/30 A GFCI breakers. *****THE MAIN PANEL 55 A BREAKER TRIPS.******

What are the causes of this ? The the only part of the whole setup which isn't a clear known is the main panel 55 GFCI and its 2 Black 2 White wires coming out of the house. A bit more on this :

4 wires come from the 55 A GFCI main panel at 220V via a metal conduit. The prior electrician who installed the feed hard wired it directly to our Cal Spas tub 15 years ago without an outdoor cut-off load . Two things:
1) Towards its last days..the Cal Spa was tripping a lot but we chalked it up to the heater gone bad. Is it possible the 55 A GFCI on our main panel is bad ?
2) I simply guessed that the 4 lines (2 Black, 2 White) running from the main panel are: 2 black 8G - Hot / 1 white 10G - Neutral / 1 white 12G - Ground. I hooked Blacks to each of the 20 / 30 A breaker posts. I hooked the 10 G white to the neutral bar next to the 20/30 A GFCI pigtails. I hooked the 12G white to a bonding strip / ground screw in the back of the cut-off load box. This was what the Hot Springs schematic shows should come from a 55 A main panel. Is it possible I mixed up the two whites ? Wouldn't the neutral be on the larger gauge ?

I guess I can switch the whites neutral for ground....but what I really need is someone to investigate the main panel 55 A GFCI breaker and have the meter to check amperage flow on the lines to be sure its not something worse ( ie- a short in the wires, damaged circuits , etc.) Hoping I just have lines crossed or bad breaker. Am I missing anything?

Guess I can post a picture of it all....

A picture would be nice. I would think it could be the wires crossed.
Couple Q's - are the two breakers GFI breakers? Is the neutral from the subpanel connected to the GFI breaker on the main? It must go straight to the breaker and not the buss bar first. If it's to the buss bar first it will trip every time.
The main panel should have a 50 amp regular breaker and the subpanel should have the 20 & 30 both GFI. The 20 should be a single pole and the 30 a double pole.

Pete
use this advise at your own risk

http://www.makesmeshutter.com

I can take a picture, but yes...both the 30 and 20 amp on disconnect panel outdoors are double pole GFCI and they run to a main 50 A GFCI. I see you note the 20 amp only needs to be single pole, but will that alone cause the main breaker trip ?

I don't understand the question about the neutral from sub panel connecting to GFI Main breaker. Rather the reverse. I identified a neutral from the main running to the subpanel. The Hot Springs schematic shows this correct and to place the Main neutral on the buss bar. There is then a neutral that runs from the 20 amp breaker to the tub. Meanwhile each pigtail from the 20/30 Amp breaker goes to the bus.

I wondered about the 50 A GFI on main. That was set up because our last tub wire direct ( out-of-code) , but its overkill to have a GFI master over two other GFI (20/30 A) on sub. Would this be enough to cause it to trip?

Also...I note that the 20 A breaker is what causes the main 50A breaker to trip. Again...just because I have a 2 pole rather than 1 pole...would this be enough to make that happen?

You can use the double pole 20 if you use only 1 leg - you can not connect 2 hots from the 20 to the spa.
All GFI breakers must have the neutral wire from the load going straight into the breaker. So if the neutral from the 50 main comes off the breaker to the sub-panel, and not from the buss bar, you are OK there.
It is possible to get nuisance tripping from 2 GFI's being close to each other.
Make sure the power jumper was changed correctly - the 3 prong comes out and the 2 prong goes to the right where the 3 prong came from.

Pete
use this advise at your own risk

http://www.makesmeshutter.com