Inspecting Grounding and Bonding at Residential Swimming Pools

According to InterNACHI’s Home Inspection Standards of Practice, an inspector is not required to inspect swimming pools or spas. However, learning the basic components and functions of residential pools, with a concentration on permanent in-ground pools, will help inspectors recognize defects in their condition and installation. One important aspect with regard to electrical safety is the proper grounding and bonding of the electrical and metal equipment of swimming pools and spas. 
  

Safety First  

It is important to remember that water and electricity don’t mix. Home inspectors should advise homeowners to consult or hire an electrician instead of doing any electrical work themselves. Always proceed with caution, and use personal protection equipment. Be aware of your surroundings when performing an inspection, especially when there are electrical components and water in close proximity to each other.

Never grab wires or components without disconnecting them from their power source. Wear rubber-soled shoes and rubber gloves. Don’t stand in water when working with or inspecting electrical equipment. Be sure to identify all circuits that are related to the pool equipment. When inspecting the pool or spa, check for unfinished or poor workmanship, particularly with the electrical components, wiring and installation. 

If conducting a visual-only inspection, stick to using your eyes only and not your hands. Don’t open anything that is not required to be opened, especially electrical components, boxes and panels. 

Check grounding wire connections, loose wires and conduits, and water leaks. Remember that water is an effective conductor of electricity. If there is an electrical problem with the pool equipment, a fault could occur and charge the entire pool or spa, making it fatally hazardous.

Grounding

The electrical equipment for swimming pools must be grounded and connected by wiring methods in accordance with the NFPA 70 National Electric Code® (NEC®).  

The following must be grounded: 

• all electrical equipment associated with the circulation system; 
• all electrical equipment located within 5 feet of the inside wall of the pool water; 
• all through-wall lighting assemblies and underwater luminaires; 
• panelboards that supply electricity to equipment associated with the pool; 
• GFCIs: 
• transformer and power supply enclosures; 
• junction boxes; and 
• pool motors. 

Grounding and bonding terminals should be identified as being used for wet and corrosive environments. Grounding and bonding connections should be made of copper, copper alloy, or stainless steel. They also should be listed for direct burial.  

Luminaries and related equipment should also be grounded. All lighting assemblies and luminaires must be connected to an insulated copper grounding conductor not smaller than 12 AWG. Where a non-metallic conduit is installed, the installation of an 8 AWG insulated copper bonding jumper may be required in the conduit. Wet-niche luminaires supplied by a flexible cord must have all exposed non-current-carrying metal parts grounded.  

An equipment-grounding conductor should be installed with the feeder conductors between the grounding terminal of the pool equipment panelboard and the grounding terminal of the applicable service equipment. 

Bonding 
Bonding is required to get all metal parts of the electrical equipment and the non-electrical metal parts of the pool/spa structure to attain equal electrical potential. Bonding of metal parts of the electrical equipment makes a low-impedance path for the fault current back to the source circuit to trip the over-current device. For equipment grounding, a separate insulated copper grounding conductor should be run to the equipment grounding terminal in the main service panel. Sheet metal screws must not be used to connect bonding conductors. 

The following parts of pools, spas, and hot tubs must be bonded together using conductors at least 8 AWG, or using rigid metal conduit, including:  

• conductive pool shells, including poured concrete, sprayed concrete, and concrete block with painted or plastered coatings; 
• structural reinforcing steel; 
• copper conductor grid; 
• perimeter surfaces that extend 3 feet horizontally beyond the inside walls of the pool, spa, or hot tub. A perimeter surface that extends less than 3 feet and is separated from the pool by a barrier shall require equipotential bonding on the pool side of the barrier. Bonding to perimeter surfaces shall be provided and be attached to the pool, spa, and hot tub reinforcing steel or copper conductor grid at a minimum of four points around the pool, spa, or hot tub. There are some exceptions; 
• metallic components;   
• underwater lighting; 
• metal fittings; 
• electrical equipment; and 
• all fixed metal parts. 

Bonding is joining metallic parts to form an electrically conductive path that will result in electrical continuity between components to ensure that the electrical potential will be the same throughout. This is referred to as equipotential bonding. Keeping the electrical potential at the same level reduces the hazard created by stray currents in the pool or in the ground around the pool. Connecting (or bonding) everything metallic in and around the pool will help eliminate voltage gradients (or differences in electrical potential) from one part of the pool to another, and from metallic equipment to the pool water.   

The following is a general list of the items that require equipotential bonding: 

• all metallic parts of the pool and spa; 
• reinforcement metal of the pool, spa, coping, shell, framing, etc.; 
• shells and mounting brackets of no-niche luminaires; 
• all metal fittings; 
• metal parts of the equipment; 
• electrical devices and controls; 
• metal cables and raceways, metal piping, and all metal parts; and 
• water heaters rated at more than 50 amperes. 
   

The bonding conductor should be at least 8 AWG or larger solid copper.  

Bonded Parts 

All metallic parts of the pool's structure, including reinforcing metal, must be bonded together using solid copper conductors (insulated, covered or bare), and at least 8 AWG, or with rigid metal conduit of brass or other corrosion-resistant metal. Connections of bonded parts must be made in accordance with the NEC® (refer to Section 250.8).  

All underwater metal-formed lighting shells must be bonded, as well as all metal fittings within or attached to the pool structure. Metal parts of electrical equipment related to the water circulation system – including pumps, motors, metal parts of pool covers and associated equipment – must be bonded. All fixed metal parts must be bonded, including metal-sheathed cables and raceways, metal piping, metal awnings, metal fences, metal doors, and metal window frames. 

Pool Shells 

Bonding to the conductive pool shells is required. Poured concrete, sprayed concrete, and concrete block with coatings must be considered conductive materials.  

The un-encapsulated structural reinforcing steel must be bonded together by tie wires. Encapsulated structural reinforcing steel must be installed with a 12x12-inch copper conductor grid. The grid must be constructed of minimum 8 AWG bare solid copper conductors bonded to each other at all points of crossing, and the grid must conform to the pool's shape, as well as be secured within or under the pool no greater than 6 inches from the outer contour of the pool's shell.  

Perimeter Surfaces 

The perimeter surface that is considered to be bonded is the area that extends 3 feet horizontally beyond the inside walls of the pool, and includes the unpaved surfaces and other types of paving. Bonding to perimeter surfaces can be attached to the pool reinforcing steel or copper conductor grid at a minimum of 4 points spaced around the pool's perimeter. 

Summary 

The electrical equipment for swimming pools must be grounded and connected by wiring methods in accordance with the NFPA 70 National Electric Code®. In addition to grounding, bonding is required to get all metal parts of the electrical equipment and the non-electrical metal parts of the pool/spa structure to attain equal electrical potential. Because the combination of water and electricity can be fatal, it is important to remember and adhere to all safety concerns and practices. Home inspectors should advise homeowners to consult or hire an electrician instead of doing any electrical work themselves.

Safety Guidlines for Home Pools
Ground-Fault Circuit Interrupters
Home Service Grounding Electrodes
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