Greetings...
Can I add a neutral bus to my houses main panel... I have one bus in there now that is for both nuetral and ground... when I go to hookup the neutral from my 220 gfci breaker to that bus I keep tripping the breaker... the spa is a 3 wire 2 hots and a ground... the instructions say to hook up the neutral from the breaker to the neutral bus the diagram shows a separate bus for the neutral and one for the ground. Any suggestions... Thanks Joe

The wire that says "load neutral" just cap and don't use because you don't have one.

You MUST connect that wire to the neutral/ground bar. 50A GFCBs don't have a "load" wire. They have a load terminal, which in your case will remain unused.

In a main panel the neutral and ground bar is the SAME. This is correct. You can add ground bar but NOT another neutral bar.

If you are tripping the breaker simply by connecting the white from the breaker to the neutral/ground bar then you have a mis-wire somewhere.

Where did you connect the ground (on both ends)?

You might not have connected the white wire from your cable feeding the circuit to the breaker, then the breaker white to the neutral bar. A GFCI breaker will have both the white and black connected to it. The breaker needs to monitor the current leaving the black and returning on the white, If it's not he same it will trip out. So both the white and black are connected to the proper terminals on the GFCI breaker.

You might not have connected the white wire from your cable feeding the circuit to the breaker, then the breaker white to the neutral bar. A GFCI breaker will have both the white and black connected to it. the breaker needs to monitor the current leaving the black and returning on the white, If it's not he same it will trip out. So both the white and black are connected to the proper terminals on the GFCI breaker.
Just so we are clear. This is a 240v, two-pole, GFI breaker. There are two hots and NO neutral in the circuit in question. It is a straight 240v circuit.

Just so we are clear. This is a 240v, two-pole, GFI breaker. There are two hots and NO neutral in the circuit in question. It is a straight 240v circuit.

That's correct, I missed the 50Amp 2 pole.