Hydromassage tub installations are covered by Section 680.70 in NEC 2002. Since there appears to be confusion about the difference between grounding and bonding, let?s go back to the basics. The requirements for the bonding of a hydromassage tub are found in Section 680.74, Bonding. In order to answer this question let?s review the following sections that apply to this type of installation:
"680.74 Bonding. All metal piping systems, metal parts of electrical equipment, and pump motors associated with the hydromassage tub shall be bonded together using a copper bonding jumper, insulated, covered, or bare, not smaller than 8 AWG solid. Metal parts of listed equipment incorporating an approved system of double insulation and providing a means for grounding internal nonaccessible, non-current-carrying metal parts shall not be bonded."
Let?s examine what bonding really is. Since there is not a definition of bonding that is specific to Article 680, we must refer to the definition of bonding found in Article 100.
"Bonding (Bonded): The permanent joining of metallic parts to form an electrically conductive path that ensures electrical continuity and capacity to conduct safely any current likely to be imposed."
In this case we are discussing bonding as it pertains to "the permanent joining of the metallic parts" of a hydromassage tub as required by Section 680.74. This requirement is to tie all metal parts together to insure that they are at the same potential. This requirement for bonding just requires you to bond the metal parts together, even though in reality, in most instances it will be tied back to the grounding electrode system through the equipment grounding conductor that is run to the pool equipment with the branch -circuit wiring. This requirement for bonding should not be confused with the requirement for grounding as provided to the pump motor by the equipment grounding conductor which is usually required to be a 12 AWG wire for a 20-amp circuit. The bonding requirement of Section 680.74 does not require you to run the required 8 AWG conductor back to the panelboard feeding the circuit that runs to the pump motor. There was a new fine print note added to Section 680.26(A) in the 2002 NEC that clarifies the intent of this requirement and should probably be added to Section 680.74 also.
"680.26(A), Performance. The bonding required by this section shall be installed to eliminate voltage gradients in the pool area as prescribed.
"FPN: This section does not require that the 8 AWG or larger solid copper bonding conductor be extended or attached to any remote panelboard, service equipment, or any electrode." ? Jim Maldonado, CMP-17
ector screw on the side of the motors used in hydromassage tubs. He says that the branch circit conductor (#12) is not large enough to handle the difference in potential that the bonding addresses using #8 solid. He agrees the purpose of the screw is for bonding exposed metal. Its what happens to the bonding after the fact(#8) that he wont budge on.
