Pool & Spa Equipotential Bonding Calculator
Find out which parts of a permanently installed pool or spa have to be tied into the equipotential bonding grid under NEC 680.26, what the bonding conductor is, and the exact subsection that governs. Pick a part and, where the answer turns on a distance or a size, enter it for a required or not-required call.
How to use this calculator
- Choose the part or component you are checking: the pool shell, the perimeter surface, metallic components, an underwater luminaire shell, a metal fitting, pool equipment, a nearby fixed metal part, or the pool water.
- Read the bonding conductor (8 AWG solid copper minimum) and the NEC 680.26 subsection that applies to that part.
- For the perimeter surface and nearby fixed metal parts, enter the horizontal distance from the inside wall (and, for a fixed metal part, its height above the maximum water level) to get a required or not-required answer.
- For a metal fitting, enter its largest dimension and how far it penetrates the pool structure to test the small-isolated-part exemption; for pool equipment, say whether it is listed double-insulated.
- All horizontal distances are measured from the inside wall of the pool; heights are measured above the maximum water level.
NEC reference
This calculator implements NEC 2020 680.26, Equipotential Bonding. 680.26(B) lists the parts that must be bonded together with a solid copper conductor not smaller than 8 AWG (or brass or another identified corrosion-resistant metal conduit): the conductive pool shell (B)(1), the perimeter surface out to 3 ft (B)(2), metallic components (B)(3), underwater luminaire forming shells (B)(4), metal fittings (B)(5), pool water-circulating equipment (B)(6), and fixed metal parts within 5 ft horizontally and 12 ft vertically of the water (B)(7). 680.26(C) covers the pool-water bond, and 680.26(A) makes clear the bonding is local and is not run back to a panelboard, the service, or a grounding electrode. The 12 in grid construction geometry and the later-edition copper-clad-steel option are out of scope here.
Results are for reference only. Verify against the applicable adopted edition of the NEC and consult a licensed electrician for code compliance.
What has to be bonded, at a glance
Every part below is tied into one equipotential bonding grid with a solid copper conductor no smaller than 8 AWG. The grid keeps the shell, the water, the deck, and the metal around the pool at the same potential, so a fault cannot put a voltage difference across a swimmer.
| Part | Bonded? | NEC |
|---|---|---|
| Conductive pool shell | Yes (reinforcing steel or #8 Cu grid) | 680.26(B)(1) |
| Perimeter surface within 3 ft | Yes | 680.26(B)(2) |
| Metallic components of the structure | Yes | 680.26(B)(3) |
| Underwater luminaire forming shell | Yes (listed low-voltage no-metal excepted) | 680.26(B)(4) |
| Metal fitting (ladder, handrail, drain) | Yes (isolated ≤ 4 in / ≤ 1 in excepted) | 680.26(B)(5) |
| Pool equipment / pump motor | Yes (listed double-insulated excepted) | 680.26(B)(6) |
| Fixed metal part, ≤ 5 ft horiz & ≤ 12 ft vert | Yes (behind a permanent barrier excepted) | 680.26(B)(7) |
| Pool water (non-conductive shell) | Yes, via a ≥ 9 in² conductive surface | 680.26(C) |
Bonding is not grounding
The most common confusion around 680.26 is treating the bonding grid as a ground. It is not. Equipotential bonding ties the conductive parts in and around the pool to each other so they share one potential; per 680.26(A) it is not required to be extended to or attached to any remote panelboard, service equipment, or grounding electrode. A single #8 solid copper loop connecting the shell steel, the perimeter, the ladder, the pump, and the nearby fence does the job. Running that loop back to the panel is neither required nor what the section asks for.
The two distance rules
Two of the seven bonded-part rules turn on a distance. The perimeter surface, 680.26(B)(2), reaches 3 ft horizontally out from the inside wall: the deck, paving, or bare ground in that band is bonded, and a surface beyond it is not. Fixed metal parts, 680.26(B)(7), are caught by a two-dimensional zone: a fence, awning, railing, or frame is bonded only when it sits within 5 ft horizontally of the inside wall and within 12 ft vertically above the maximum water level. Outside either limit it falls out, and a part separated from the pool by a permanent barrier is excepted even inside the zone. This tool resolves the 3 ft, 5 ft, and 12 ft boundaries to the bonded side, so a part exactly at a limit is treated as requiring the bond.
Worked example: a backyard gunite pool
A conductive gunite shell is bonded through its structural reinforcing steel, tied together and connected to the #8 solid copper bonding grid (680.26(B)(1)). The concrete deck for 3 ft around the pool is bonded as the perimeter surface (680.26(B)(2)). The stainless ladder and handrail are metal fittings and are bonded (680.26(B)(5)); a small isolated deck anchor no more than 4 in across that penetrates less than 1 in need not be. The pump motor is bonded (680.26(B)(6)) unless it is a listed double-insulated pump, in which case its metal is left off the grid and a spare #8 conductor is left for a future replacement. An aluminum fence 4 ft from the water and 6 ft tall is a fixed metal part inside the 5 ft / 12 ft zone and is bonded (680.26(B)(7)); the same fence 8 ft away is beyond the 5 ft reach and is not.
Common mistakes
- Using stranded wire. The bonding conductor must be 8 AWG solid copper, not stranded (680.26(B)).
- Running the bond back to the panel. 680.26(A) does not require it; the grid is local.
- Skipping the perimeter deck. The 3 ft band of deck or ground around the pool is a bonded surface, not just the shell.
- Forgetting nearby metal. A fence or railing within 5 ft horizontally and 12 ft vertically is a bonded fixed metal part.
- Bonding a double-insulated pump. Bonding the metal of listed double-insulated equipment defeats the double insulation and is not done.
- Confusing bonding with grounding. They are separate requirements; equipotential bonding does not replace the equipment grounding conductor.
Frequently asked questions
What size wire is used for pool bonding?
Solid copper, insulated, covered, or bare, not smaller than 8 AWG, under 680.26(B). Brass or another identified corrosion-resistant metal conduit may also bond one part to another. The copper must be solid, not stranded.
How far around a pool has to be bonded?
The perimeter surface extends 3 ft horizontally beyond the inside walls under 680.26(B)(2), including paved and unpaved surfaces. A surface separated from the pool by a permanent wall or building at least 5 ft high is bonded only on the pool side.
Does a metal fence near a pool need to be bonded?
Yes, when it is within 5 ft horizontally of the inside wall and within 12 ft vertically above the maximum water level, under 680.26(B)(7). A fixed metal part separated from the pool by a permanent barrier is excepted.
Does a pool ladder have to be bonded?
Yes. Metal fittings within or attached to the pool structure are bonded under 680.26(B)(5). The only exception is an isolated part not over 4 in in any dimension that penetrates the structure no more than 1 in.
Is pool bonding the same as grounding?
No. Equipotential bonding ties the parts around the pool together so they share one potential, and per 680.26(A) it is not run back to a panelboard, the service, or a grounding electrode. Grounding is a separate requirement.
Related calculators
- Swimming Pool & Spa Equipment Clearance Calculator: receptacle, luminaire, and switch clearances from the water per NEC 680.22 and 680.43.
- GFCI Breaker Sizing Calculator: where GFCI protection is required and how to size the breaker.
- Working Space Clearance Calculator: the working space in front of electrical equipment per NEC 110.26(A).
- Overhead Conductor Clearance Calculator: vertical clearance of an overhead span over ground and roofs per NEC 230.24 and 225.18.
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