Master Electrician Exam (NEC)Special Occupancies, Equipment, and ConditionsMedium
A master electrician is planning the electrical installation for a new indoor swimming pool at a residential property. The pool is 20 feet long and 10 feet wide. Which of the following statements regarding the grounding and bonding requirements for the pool is correct according to the NEC?
- AThe equipotential bonding grid must extend 3 feet horizontally from the inside wall of the pool and be 4 to 6 inches below the subgrade.
- BUnderwater luminaires operating at more than 15 volts must be supplied by an approved isolating transformer.
- CAll metal parts of the pool structure, including reinforcing steel, must be bonded together with a solid copper conductor not smaller than 10 AWG.
- DAll metallic parts of the pool structure, including reinforcing steel, must be bonded together and connected to the grounding electrode conductor.
Show answer & explanationAnswer & explanation
Correct answer: C. All metal parts of the pool structure, including reinforcing steel, must be bonded together with a solid copper conductor not smaller than 10 AWG.
NEC 680.26(B)(1) requires all metal parts of the pool structure, including reinforcing steel, to be bonded together with a solid copper conductor not smaller than 8 AWG. Option A correctly identifies the bonding requirement for metal parts.
Why the other options are wrong
- A. This describes the equipotential bonding grid requirements (680.26(B)(1)(b)), but the conductor size is 8 AWG, and the depth is typically 4 to 6 inches below the finished grade, not subgrade, and specific to the concrete pad, not necessarily the entire 3-foot horizontal extension uniformly below subgrade.
- B. This is a correct NEC requirement (680.23(A)(2)), but it's about underwater luminaires, not the general grounding and bonding of the pool structure itself, which is the focus of the question.
- D. While bonding is required, connecting directly to the grounding electrode conductor is not the primary bonding method for these specific components. Bonding is typically to the common bonding grid.
Swimming Pool Bonding (NEC)
The National Electrical Code (NEC) mandates the equipotential bonding of all metal parts associated with a swimming pool to minimize voltage gradients in and around the pool area, preventing dangerous shock hazards.
- All metallic parts of the pool structure, including rebar, must be bonded.
- Bonding conductors for these parts must be solid copper, not smaller than 8 AWG.
- Bonding creates an equipotential plane around the pool.
Memory trick: Pool Safety: Bond All Metal, Ground All Wires, Protect All Swimmers.