Article 680 Part VII for hydromassage bathtubs (jacuzzi). In your particular case I would take a #8 and go from the bonding lug on the motor and return it to another bonding lug on the same motor, about an inch or so from the first lug. Cause why not? There ain't nothing else to bond to unless this particular tub is made out of iron and even then the code would not require it. Spa's and hot tubs are in a different part of 680 and have different rules. Lots of inspectors get it all mixed up and so do lots of electricians.
