The size of the Hot Tub determines the size of the wire that is used. This would be determined by looking at the name plate on the hot tub.
All spas & hot tubs must be GFCI protected (680.44), with these three exceptions:
- If the unit is a listed packaged equipment assembly that contains its own integral GFCI. - 680.44(A)
- If the unit is rated for 3-phase or for operation at over 250V or with a heater load in excess of 50A. - 680.44(B)
- The spa or hot tub is a combination pool/hot tub or spa assembly that is commonly bonded. - 680.44(C)
However, most would need GFCI protection.