Electricity always travels the shortest path to the earth, so the trick with electrical safety is making sure you don’t become part of that path.

One of the main ways this is accomplished is through grounding, which means exactly what it sounds like: deliberately connecting parts of a wiring installation to the earth. A metal rod is driven deeply into the ground and metal piping that is part of an underground water system.

A wiring installation that is properly grounded allows excess electrical current (such as from a lightning strike) to safely go into the ground without hurting someone or damaging the electrical components.

Bonding

Within a pool setting, electrical bonding is a practice of connecting the conductive elements of the pool structure, nearby metallic objects, and electrical equipment enclosures together. The National Electric Code (NEC) requires bonding to eliminate voltage differences in the pool area. When all metallic parts are bonded together, they effectively eliminate differences of voltage potential that may exist between the individual conductive parts and thus reduce the shock hazard.

When these metallic conductive parts are not bonded together, they have a possibility of being at different voltage potentials. If a potential difference exists between two conductive parts and a person touches them simultaneously, that person’s body can become a conductor of electric current and might experience an electric shock.

However, if the conductive parts had been intentionally, mechanically, and electrically joined together, a potential difference cannot exist between the metal parts. That typically eliminates the possibility of a shock hazard because the conductive parts are always at the same potential.

The main purpose of the equipotential bond for swimming pools is safety in the case of a fault. Stray current, either from equipment failure or from some factor completely unrelated to the swimming pool can cause voltage gradients within the pool system.

For example, because electrical supply systems that deliver power to homes and facilities are grounded, there is a small amount of current that flows to the earth. Associated with this current is a small voltage that develops at each point where the electrical system is grounded. That voltage is called neutral to earth voltage. Neutral to earth voltage causes voltage gradients that depend on the distance from the voltage source. If the pool is not bonded, these are often experienced as small shocks while touching different areas of the pool simultaneously.

This is not uncommon. In an online forum, a homeowner complained swimmers were getting shocked while sitting on the coping with their feet in the pool. They also felt a small shock or electrical current on the metal handrails and on the cement on one side of the pool. They experimented with the pump on and off and could always feel something. They got a bigger shock if they had any cuts or abrasions on their skin.

This is a case of stray current, caused by stray voltage, which could have been caused by any number of factors. It could be from their electric feed, a neighbor’s place, perhaps the power company’s equipment, or even the telephone system. If the pool were properly bonded, it almost certainly would not be felt.

So bonding is a safety precaution to reduce the shock hazard from the conductive components within the pool environment.

The NEC requires bonding conductive components in the pool area that, if followed correctly, helps reduce electric shock hazards to acceptable levels.

What is required to be bonded?

The bonding requirements for a swimming pool can be found in the NEC 680.26 and are summarized as follows. Each of these components must be bonded together with a solid copper conductor not smaller than 8 AWG (American Wire Gauge) and with listed pressure connectors or clamps that are labeled as suitable for the purpose. These are to be made of stainless steel, brass, copper or copper alloy.

1.All metal parts of the pool structure, including the rebar metal of the pool

shell must be bonded. Normal steel tie wires are considered acceptable for bonding the reinforcing steel together. Welding is not required. Encapsulated rebar, such as rebar insulated by a nonconductive epoxy coating must meet additional requirements.

Vinyl liners and fiberglass shells are considered non-conductive and the shells are not included in the bonding requirements 2. Coping stones and deck must be bonded. Rebar can be used to extend the deck bonding. The bonding must extend a minimum of three feet horizontally beyond the inner pool walls at a minimum of four points uniformly spaced around the perimeter of the pool.

3. All metal forming shells of pool lights and mounting brackets for pool lights must be bonded. Some low-voltage lighting systems with nonmetallic forming shells are not required to be bonded.

Check manufacturer’s instructions to ensure compliance with the code.

4. All metal fittings 4 inches or larger located within or attached to the pool structure must be bonded. This includes ladders and handrails and the associated metal cups.

5. Metal parts of electric equipment associated with the pool water circulating system, such as water heaters, pump motors, and metal parts of pool covers, including electric motors, must be bonded.

6. All fixed metal parts such as metal-sheathed cables and raceways, metal piping, and metal awnings, metal fences, and metal door and window frames must be bonded. Bonding requirements apply to all fixed metal parts that are within 5 feet horizontally of the inside walls of the pool, and within 12 feet above the maximum water level of the pool.

7. The pool water itself must also be bonded. An intentional bond of a minimum conductive surface area of 9 square inches is required to be in direct contact with the pool water at all times. This bonding can be accomplished with any of the conductive parts that are required to be bonded such as a metal pool ladder or railing where at least 9 square inches of the ladder is in contact with the water. The metal forming shell of a wet-niche pool light could also satisfy this bonding requirement.

Electrical Safety

• When working on electrical systems, it is essential to turn off the power. Turn the power off at the service panel prior to working with wiring. Padlock the electrical box to prevent an unauthorized person from turning the power back on while work is being done. Carry a lock and key for this purpose.

• Use tools with insulated handles. Insulated materials such as rubber, wood, glass and ceramic are appropriate. Stand on a dry and insulated platform. Carry a rubber mat for this purpose. Keep yourself and your clothing as dry as possible. Wear rubber soled shoes. Remove jewelry.

• Wear safety glasses.

• Be sure that the pool and equipment is properly bonded. Pay special attention to pump motors, switch boxes, and metal pipes.

• Ensure that all metal enclosed equipment is properly grounded.

• Using test meters, ensure that a circuit is not electrically charged before handling wires. Be sure that the meter can withstand the voltage and current range because a meter set for a 120 VAC range will not survive if it is used on a 240 VAC circuit.

• Take care not to touch live metal equipment. Test for this using a voltmeter to see if there is a voltage between the metal housing on the equipment and the earth ground (usually a water pipe). There should not be a voltage reading. If there is, a shock can occur as the current travels to ground.

• Take care not to touch live wires or a severe shock may ensue.

• Don’t let live wires come into contact with a ground. A circuit breaker or fuse will be blown. Heaters, water pipes, and similar items are grounded.

• Use a GFCI outlet for power around swimming pools, spa, or water. If one is not available, carry a portable one.

• Replace all worn electrical wires. Check that the insulation is in place and in good condition.

• Before working on capacitors, short circuit them or risk shock. A capacitor may be used in the start winding and the running winding of the pump motor. To discharge a capacitor, use a screwdriver to make contact between the two terminals. Be sure to wear safety goggles.

• Don’t attempt electrical work without understanding the basics of wiring, understanding wiring diagrams, and having wiring experience.