Adding GFCI Breaker to Existing Subpanel
I want to add a GFCI breaker to an existing sub panel (used to power a hot tub) so I can have a protected outlet on my patio. However, I'm confused as to how to wire in to the existing wiring.
The existing sub panel has a double pole 50A breaker with 2 hot wires (red and black) and a neutral white wire plus a green ground. At the sub panel, the white wire and ground are ganged onto the same bus. I traced the wires going to the sub panel and verified the white is connected to the main house neutral, while the black and red come from another 50A 2-pole breaker on the main panel.
My confusion lies with the white neutral being connected to ground at the sub panel. I thought that GFCI breakers require the neutral and ground to be separate. If so, how can I add a GFCI to this sub panel?
Thanks,
HDD