Background:
-Artesian Spa - I do not know the model as I inherited it with the house I bought. It is definitely an older spa.
-Cutler Hammer CH250GF - a two pole 240 V 50 A GFI breaker.
-Wiring - as follows:
RED from tub - attached to one of the poles
BLACK from tub - attached to one of the poles
WHITE from tub - attached to the load neutral on the GFI
WHITE from the GFI - attached to breaker box buss bar

Here is the problem:
I cannot get the 'TEST' button on my Cutler Hammer CH250GF GFI breaker to trip. It seems that it should only activate as long as the proper voltage is present. I can easily measure 120 Volts between each lead and ground, and a full 240 V between the two leads. The tub works fine but I cannot get the thing to trip. My hot tub contractor claimed that the GFI was bad so I bought a new one. However, it shows the exact same behavior. I can't believe that both GFIs are faulty.

Please help if you can!

Be sure the power coming intothe sub-panel from the house is good- double check your neutral and Ground wires, be sure they're adequate.

Always a chance you got 2 bad GFCI's exhibiting the same behavior, but chances are against it. Be sure the Ground is good, be sure the neutral is good. The breaker is wired properly, but you might have a bad ground or bad Neutral between the subpanel and the main.