Further looking suggests 6-3 cable if it has a ground will have a #10 AWG ground wire.

http://buyawg.thomasnet.com/viewitem...b-and-type-mc#

So this makes me wonder about your pump motor and Salt System controller. If both are 220V then the neutral current will be zero (desirable). Here there will be no voltage drop on the neutral wire because the load will all be on the 220V wires. This would eliminate any voltage between ground and neutral unless something else is wrong like a poor ground at the main panel.

I hope you are NOT using a 120V pump from one side hot to neutral. This creates unbalance resulting in voltage between ground and neutral. This would be even worse if the electrician used the 10 AWG wire as the neutral wire.

If you have voltage between different points around your pool, and you have a Salt system, expect for rapid galvanic corrosion to take place. Left unchecked that could cost you a fortune to fix.

Jim