This month I would like to discuss Whirlpool tub GFCI protection and bonding. A whirlpool tub (hydromassage tub in the National Electrical Code) is drained after each use, typically located in a residential bathroom.

All electric equipment, including the pump motor, requires GFCI protection to protect people from fatal shock. Most typical residential installations utilize a dedicated 20-Amp circuit with the GFCI protection located at the originating breaker or the receptacle outlet near the motor. Often the GFCI is in a wall receptacle in the bathroom or adjacent room such as a closet. Be sure to look behind hanging towels and clothing before assuming there is no GFCI protection. In addition to the phase conductors this circuit also must contain an equipment grounding conductor connected to the labeled termination point in the pump motor junction box. The equipment grounding conductor provides a path for fault current back to the transformer should there be a malfunction. If the pump has a “double insulated” motor, it does not need an equipment ground, and the GFCI is still protecting people against shocks.

Bonding is the connection of equipment with a conductor to ensure each part has equal potential to ground. Modern whirlpool tub installations require that all grounded metal parts in contact with the circulation water be bonded together with a minimum #8 solid copper conductor. This conductor should terminate at the lug at the exterior casing of the motor.

Just because there is a bonding lug on the pump motor does not mean something has to be connected to it. Most modern whirlpool tubs are piped with plastic and the only metal component is the pump, so a bonding conductor is not necessary as the pump is already bonded to the equipment ground. If there is a mixture of metal and plastic the metal pipe and tubing should be bonded to the motor casing. Small isolated metal components, such as the donuts that go around the inlet jets, do not need to be bonded.

We'll talk next month,

Mike Casey
Kaplan Professional Schools
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