I just installed a spa with 4 wires. The house is old and while the neutral & ground bus bars are separate in the spa panel, they are all on the same bar in the main panel. Do I need to install a ground rod by the spa panel to keep the gfci from tripping? (instead of running the ground back to the main panel neutral/ground bus bar)

Hi,
It sounds like either the wiring is incorrect, or you have a problem with the spa equipment. Something is grounding out (shorting out) that causes the GFCI to trip.

I'd stay out of that water until you can get the equipment checked by an electrician...

Ground and Neutral are on the same bus in my panel, no problem there. Double-check that you've wired correctly, but maybe corrosion has caused one of your pumps or motors to ground-fault?

Good luck, j

First of all, do not install a ground rod. This will not solve your problem with the GFI, and is a code violation. Too much detail to explain here why,please take my word for it.

The GFI breaker has a neutral wire coming off it that must go the neutral bar in the panel. The white load wire, from the spa must connect to the screw terminal under or near this white wire on the GFI breaker. Many times this white wire from the load is connected improperly. Check to be sure this is done correctly. The terminal for the white load wire on the breaker sometines is hard to see. I know because I have missed it myself. This is a popular reason for GFI to trip on a new spa.

The neutral and equipment ground are to be connected at the main panel, only, and separate at any subpanel, so that's correct.

Check the GFI breaker to be sure the load white is connected properly, I bet that is the problem.

There are 2 people here you want to follow their instructions exactly, tkrussel and Tom in plumbing. Before they came, I didn't realize how little I knew.

Your question sounded like it should work, but I didn't know what to tell you to look for.

Unplug or disconnect spa motor, GFI doesn't trip? Change motor.
Repeat for other features. Blower etc...