A pool has two separate conductor systems, and the code goes out of its way to keep them apart. One of them is the equipment grounding conductor that runs with the feeder. The other is the equipotential bonding grid, and the clause that creates it says in one sentence that a bonding conductor provided to reduce voltage gradients in the pool area is not required to be extended or attached to remote panelboards, service equipment, or electrodes.
That sentence is the whole article. A reader who assumes that bonding and grounding are two words for the same job will run a conductor back to the panel that the code does not ask for, and will miss the conductor it does.
Two systems, two purposes
The bonding requirement states its own purpose, and it is not fault clearing. The equipotential bonding shall be installed to reduce voltage gradients in the pool area. Nothing in the clause mentions a fault, a breaker or a return path.
| The feeder’s equipment grounding conductor | The equipotential bonding grid |
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What it is for | Providing the fault current path back to the source | Reducing voltage gradients in the pool area |
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Where it terminates | Between the grounding terminal of the pool equipment panelboard and the grounding terminal of the service equipment or the source of a separately derived system | On the bonded parts themselves. It is not required to be extended or attached to remote panelboards, service equipment or electrodes |
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May it be bare? | No, in general. It must be insulated except in two named cases | Yes. The bonding conductors may be insulated, covered or bare |
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Two further clauses confirm that the code treats the two as separate systems rather than as two ends of one. Where a double-insulated water pump motor is installed, a solid 8 AWG copper conductor must be extended from the bonding grid to an accessible point near the motor, and the clause then says: where there is no connection between the swimming pool bonding grid and the equipment grounding system for the premises, this bonding conductor shall be connected to the equipment grounding conductor of the motor circuit. The code explicitly contemplates an installation in which the grid and the grounding system are not connected at all, and gives an instruction only for that case.
The second clause is blunter. For a pool water heater rated at more than 50 amperes and having specific instructions regarding bonding and grounding, only those parts designated to be bonded shall be bonded and only those parts designated to be grounded shall be grounded. The manufacturer’s drawing is allowed to name two different lists, and the installer is not permitted to merge them.
What has to be bonded, and it includes the water
The bonding clause lists the parts that must be bonded together, and the list is longer than a reader expecting metal fittings would guess.
Bonded part | Requirement |
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Conductive pool shells | Bonded either through the structural reinforcing steel or through a copper conductor grid |
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Perimeter surfaces | Extending 1 m (3 ft) horizontally beyond the inside walls of the pool, including unpaved surfaces and paving |
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Metallic components | All metallic parts of the pool structure, including reinforcing metal not otherwise addressed |
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Underwater lighting | All metal forming shells and mounting brackets of no-niche luminaires |
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Metal fittings | All metal fittings within or attached to the pool structure |
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Electrical equipment | Metal parts of equipment associated with the water circulating system, including pump motors, and metal parts of equipment associated with pool covers, including electric motors |
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Fixed metal parts | All fixed metal parts meeting the dimensional tests described below |
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The pool water | An intentional bond of a minimum conductive surface area of 5800 mm² (9 in.²) installed in contact with the water |
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The last entry is the one that surprises. The water itself is a bonded part, and what is specified is a surface area in contact with the water rather than a conductor size. The clause also permits that bond to consist of parts that are already required to be bonded, which is how ladders, handrails and light shells end up doing the work.
The conductor that does all of this is specified once, in the opening paragraph: solid copper, insulated, covered or bare, not smaller than 8 AWG, or rigid metal conduit of brass or other identified corrosion-resistant metal. Eight AWG, in solid copper, for every bonded part.
Concrete is conductive, and vinyl is not
The clause that decides how much work a pool shell needs is a materials rule rather than an electrical one.
Poured concrete, pneumatically applied or sprayed concrete, and concrete block with painted or plastered coatings are all considered conductive materials, because of water permeability and porosity. Vinyl liners and fiberglass composite shells are considered nonconductive.
That single distinction changes the installation. A conductive shell must be bonded either through its structural reinforcing steel, bonded together by steel tie wires or the equivalent, or through a copper conductor grid where the steel is encapsulated in a nonconductive compound. A nonconductive shell does not require a grid, and the perimeter bonding does not have to be attached at four points.
What is bonded, and what may be left unbonded
The grid, dimensioned
Where a copper conductor grid is used, four requirements fix its geometry, and together they describe something a reader can build.
Requirement | Value |
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Conductor | Minimum 8 AWG bare solid copper, bonded to each other at all points of crossing |
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Spacing | A 300 mm (12 in.) by 300 mm (12 in.) network of conductors in a uniformly spaced perpendicular grid pattern, with a tolerance of 100 mm (4 in.) |
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Position | Secured within or under the pool, no more than 150 mm (6 in.) from the outer contour of the pool shell |
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Perimeter attachment | Attached to the reinforcing steel or the grid at a minimum of four points, uniformly spaced around the perimeter of the pool. Not required at four points for a nonconductive shell |
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Where structural reinforcing steel is not available, or is encapsulated in a nonconductive compound, an alternate means applies: at least one minimum 8 AWG bare solid copper conductor following the contour of the perimeter surface, only listed splices permitted, installed 450 mm to 600 mm (18 in. to 24 in.) from the inside walls of the pool, and secured 100 mm to 150 mm (4 in. to 6 in.) below the subgrade.
The 100 mm tolerance on a 300 mm grid is a working tolerance rather than a target, and the 150 mm positioning limit is measured from the outer contour of the shell rather than from the water.
The grid, its spacing and its position
What may be left unbonded
Most of the exceptions in this subject are dimensional, and they are the reason two identical-looking pool areas can have different bonding scopes.
Provision | What need not be bonded |
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Metal fittings | Isolated parts that are not over 100 mm (4 in.) in any dimension and do not penetrate into the pool structure more than 25 mm (1 in.) |
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Reinforcing steel | Steel encapsulated in a nonconductive compound |
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Underwater lighting | Listed low-voltage lighting systems with nonmetallic forming shells |
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Electrical equipment | Metal parts of listed equipment incorporating an approved system of double insulation |
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Fixed metal parts | Those separated from the pool by a permanent barrier that prevents contact by a person |
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Fixed metal parts | Those greater than 1.5 m (5 ft) horizontally from the inside walls of the pool |
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Fixed metal parts | Those greater than 3.7 m (12 ft) measured vertically above the maximum water level, or above any observation stands, towers, platforms or diving structures |
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The metal fitting test is the most useful one on site because it is conjunctive. A part that is small enough but penetrates more than 25 mm is bonded; a part that does not penetrate at all but is 150 mm across is bonded. Both halves have to be satisfied.
The 1.5 m and 3.7 m figures are what keep a pool bonding scope from growing without limit. A metal downspout or a structural column at the far end of a deck is outside both, and does not need a bonding conductor run to it.
The feeder is almost always in conduit
The feeder requirements begin with a wiring method that leaves very little choice, and the exception is the part a cable supplier should read.
Feeders shall be installed in rigid metal conduit or intermediate metal conduit. If they are not subject to physical damage, liquidtight flexible nonmetallic conduit, rigid polyvinyl chloride conduit, reinforced thermosetting resin conduit, electrical metallic tubing installed on or within a building, electrical nonmetallic tubing installed within a building, and Type MC cable installed within a building and not subject to a corrosive environment are also permitted.
Type MC is the only cable on that list. A pool feeder run as a cable has to be Type MC, has to be inside a building once it is a cable, and has to be in a location that is not corrosive. Everything else on the permitted list is a raceway.
An existing feeder between an existing remote panelboard and service equipment is excepted and may run in flexible metal conduit or an approved cable assembly that includes an equipment grounding conductor within its outer sheath. And aluminum conduit is not permitted in the pool area where it is subject to corrosion — which is a materials decision made by the environment rather than by the load.
The permitted feeder wiring methods
The feeder’s grounding conductor must be insulated
The requirement that separates the two conductor systems most sharply in practice is in the feeder clause rather than the bonding clause.
An equipment grounding conductor shall be installed with the feeder conductors between the grounding terminal of the pool equipment panelboard and the grounding terminal of the applicable service equipment or the source of a separately derived system. And then: for other than an existing feeder covered by the exception, or a feeder to a separate building that does not use an insulated equipment grounding conductor, this equipment grounding conductor shall be insulated.
A bare conductor is therefore not acceptable as the feeder’s grounding conductor in a new pool installation. It has to be insulated. The bonding conductors, by contrast, are expressly permitted to be bare — the same 8 AWG, in the same pool area, with the opposite requirement attached, because the two are doing different jobs.
The size is set by the general equipment grounding conductor table but carries its own floor: not smaller than 12 AWG, and not smaller than 8 AWG on a separately derived system. A feeder to a separate building may supply pool equipment branch circuits where the grounding arrangements at that building meet the separate-building requirements, and the separate grounding conductor must then be an insulated conductor.
FAQ
Does the pool bonding grid have to be connected to the electrical panel?
No. A bonding conductor of 8 AWG or larger provided to reduce voltage gradients in the pool area is not required to be extended or attached to remote panelboards, service equipment or electrodes. The bonding conductor runs between the bonded parts.
Can the feeder’s equipment grounding conductor be bare?
Not in a new installation. The feeder’s equipment grounding conductor must be insulated, except for an existing feeder between an existing remote panelboard and service equipment, or a feeder to a separate building that does not use an insulated equipment grounding conductor. The bonding conductors in the same pool area may be insulated, covered or bare.
Conclusion
A pool area contains two conductor systems with different purposes, different termination points and different insulation requirements. The equipotential bonding grid exists to reduce voltage gradients, it may be bare, its conductors are not smaller than 8 AWG solid copper, and it is expressly not required to reach a panelboard, service equipment or an electrode. The feeder’s equipment grounding conductor exists to carry fault current, it must normally be insulated, and it runs between two grounding terminals.
Everything else in the subject follows the materials. Concrete is conductive because water passes through it; vinyl and fiberglass are not. The shell’s material decides whether a grid is needed. The metal fitting test is conjunctive. The fixed metal part exceptions are measured in meters. And of the permitted feeder wiring methods, exactly one is a cable, and it is permitted only indoors and only where the environment is not corrosive.
Cable for a pool area, and what the environment rules out
ZONG Cable supplies the constructions that survive a chlorinated, humid equipment room, and can confirm what a jacket and a conductor are rated for rather than what they look like. Tell us the wiring method the drawing calls for and the environment the run passes through, and we will confirm what the construction carries. The range sits under cable, the difference between bonding for voltage gradients and grounding for fault current is set out more generally in the guide to telecommunications grounding and bonding, what a listing actually proves when a clause requires listed splices or listed equipment is covered in test report validity, the reaction to fire and material question that decides a jacket in a damp space is worked through in LSZH versus PVC jacket selection, the aluminum question behind the corrosion restriction is covered in copper-clad aluminum conductor verification, and private-label construction to a project specification is handled under OEM support.
Sources
- NFPA 70, National Electrical Code, 2011 edition, Article 680, Swimming Pools, Fountains, and Similar Installations. Read directly for this article: 680.1 Scope; 680.2 Definitions; 680.3 Other Articles; 680.4; 680.5 Ground-Fault Circuit Interrupters; 680.6 Grounding; 680.7; 680.8 Overhead Conductor Clearances; 680.9; 680.10 Underground Wiring Location; 680.11; 680.12; 680.20 General; 680.21 Motors; 680.22 Lighting, Receptacles, and Equipment; 680.24 Junction Boxes and Electrical Enclosures; 680.25 Feeders, including paragraph (A) Wiring Methods with subparagraph (1) and its permitted list and exception and subparagraph (2) on aluminum conduit, and paragraph (B) Grounding with subparagraphs (1) Size and (2) Separate Buildings; 680.26 Equipotential Bonding, including paragraph (A) Performance, paragraph (B) Bonded Parts with its opening conductor requirement and subparagraphs (B)(1) Conductive Pool Shells with items (a) and (b) and the grid conditions, (B)(2) Perimeter Surfaces with items (a) and (b), (B)(3) Metallic Components, (B)(4) Underwater Lighting with its exception, (B)(5) Metal Fittings, (B)(6) Electrical Equipment with its exception and items (a) and (b), and (B)(7) Fixed Metal Parts with its three exceptions, and paragraph (C) Pool Water; and 680.27 Specialized Pool Equipment, including (A) Underwater Audio Equipment with subparagraphs (1) Speakers, (2) Wiring Methods and (3) Forming Shell and Metal Screen, and (B) Electrically Operated Pool Covers. Source text read from a full-text copy of the 2011 edition.
- ZONG Cable range. https://zh-zong.com/cable/
