Can I run a neutral wire from my main panel bar which has both neutral (white) and bare grounds on it to 1 of 2 bars in a spa pack box containing a 50 amp gfci and 2 separate ground/neutral bars without this causing a fault and tripping my gfci? The 2nd bar in the pack I plan to use a equipment ground and running a new copper strand and ground rod outside of where this connection takes place. I know it needs to be an isolated and separate neutral connection, will running it in this manner make it such? I am trying to gain a 4 wire connect to my spa.I haver got the 2 hots no prob. The neutral is what I am questioning. Should the bar in my main be used as a neutral in my spa pack or ground? (both are running into it at main)If used as a ground then where must I get the neutral from at panel to run to my spa pack gfci? HOpe I have been clear, if pics or further explanation necessary please reply.
Thanks
This is for a 240v 4 wire connect to spa.2 hots from main using 50 amp breaker at main and 50 amp gfci breaker with 2 bus bars built into plastic spa pack box.

Pics would help. In your main panel you should have 2 separate 'ground bars'. One should have all white wires in it and not be bonded to the panel (neutral). The other should have bare wires and be bonded (ground). You need the neutral for the GFI to work. The neutral bar in the spa panel should be fed from the white wire you connect to the neutral bar back at the main panel. Make sure it is isolated. Then breaker neutral wire goes into the same bar.