Pool Equipotential Bonding and Pump GFCI
An existing in-ground swimming pool has a 240V, 1.5 hp pump motor fed by 12 AWG THHN in PVC conduit from a dwelling panel. The pump is about 40 ft from the panel. The motor is connected with a 12 AWG equipment grounding conductor. The pool has a stainless-steel ladder, an aluminum handrail, and a metal light niche; the water is not bonded. The homeowner replaced the pump and now reports a mild tingling sensation when touching the ladder while standing on the wet deck. A voltmeter shows about 1.5V between the pool water and the ladder. The pump motor is not GFCI protected. The contractor proposes to drive a new ground rod at the pool equipment and connect it to the pump housing, saying that will 'ground the pool.' The inspector must determine the cause and the required correction.
1. Why does the tingling occur, and why is a ground rod at the pump not the correct fix?
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The tingling is a voltage gradient caused by a missing or ineffective equipotential bonding grid, not by a lack of a ground rod. A ground rod does not create an equipotential plane and may actually increase the voltage gradient between the water, the ladder, and the deck.
NEC 680.26 requires all metal parts of the pool, including the ladder, handrail, light niche, pump motor, and the pool water, to be bonded together with a bonding conductor and listed fittings. The equipment grounding conductor for the pump is a fault-return path and does not substitute for bonding. The 1.5V reading between the water and the ladder shows that the water and the ladder are at different potentials.
The correct fix is to install a listed water bonding fitting and connect it to the bonding grid, then bond the ladder, handrail, light niche, and pump motor. A ground rod at the pump does not satisfy 680.26 and does not eliminate the potential difference.
2. What specific bonding and protection must be installed for the pump and pool?
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Install a bonding conductor, typically 8 AWG solid copper, run per 680.26(B), connecting the pump motor bonding lug, the stainless-steel ladder, the aluminum handrail, the metal light niche, and any other metal fittings. Install a listed water bonding fitting in the pool circulation piping or skimmer and bond it to the grid. The bonding conductor is separate from the equipment grounding conductor but must be bonded to it at the pool equipment.
The pump branch circuit also requires GFCI protection under 680.21(C) for the pool pump motor. The 12 AWG equipment grounding conductor must be connected to the motor frame. Test continuity of the bonding grid; all parts must be electrically continuous.
Do not use the ground rod as a substitute for the bonding grid. The bonding grid equalizes potential, while the EGC and GFCI provide fault protection.
3. The pump is 40 ft from the panel and the existing 12 AWG circuit is protected by a 20A breaker. Is that acceptable for the 1.5 hp motor, and what about the GFCI?
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Table 430.248 gives a full-load current of 10A for a 1.5 hp, 230V single-phase motor. 430.22 requires branch-circuit conductors at 125% of the full-load current: 10A x 1.25 = 12.5A. 12 AWG copper is acceptable for that load.
430.52 permits an inverse-time breaker at up to 250% of the full-load current: 10A x 2.50 = 25A. A 20A breaker is acceptable if it starts the motor without tripping. The 12 AWG equipment grounding conductor is also acceptable for a 20A circuit under Table 250.122.
The circuit needs GFCI protection under 680.21(C). A 20A GFCI breaker is a practical solution for a hardwired pool pump. Verify the motor disconnect is within sight and that the bonding requirements from the previous questions are completed before the circuit is energized.