Equipotential bonding creates a connection between all of the potentially conductive elements, electrical components, and metallic objects within a pool area, within five horizontal feet of the water.
How is it that swimming pools can have large pieces of electrical equipment near them and literally inside them, in the water, without proving to be a safety risk for those in the pool? We all have seen warning labels on electrical appliances not to use them near the water because of the risk of electrocution. How, then, is it ok to do things like placing electrical lights with metal housings inside pools? Does that not pose a similar risk to those who enter the pool? The answer is simple - not if the components and the pool are both bonded and grounded as needed.
Shock hazards arise when there are voltage differentials between components because they allow electrical currents to pass between them through a conductor. If the voltage readings of neighboring components are equal, then the risk of enduring a shock that could prove fatal is diminished or eliminated. It is easy to think that the way to fix this problem is by grounding the circuit. We have all seen ground wires in electrical outlets, ceiling fans, and other household items. The real process behind creating a safe swimming pool often does NOT involve grounding, however. Instead of returning the circuit to a non-conductive surface or to the ground of the earth, the main process of ensuring electrical safety around a swimming pool is equipotential bonding, not grounding.
How does equipotential bonding keep you safe in a pool area?
Because a human body can conduct electricity, if there is a difference in the potential voltage of elements near the pool and the water, the electricity could pass through the human, causing a lethal shock. In order to safeguard this from happening, a grid of rebar and connective bonding jumpers bond the elements together. If these components are correctly bonded, there is no difference in the potential voltage of the various components, so there is no impetus for the electricity to travel through a conductor, such as a human body. Without taking these steps, elements like the metal housing around a pool light can prove a lethal addition to a pool instead of an amenity.
If the pool has a conductive shell, such as one made of concrete and not vinyl, this component must be bonded to the perimeter surfaces or the deck. The perimeter surface must include a grid of rebar that the conductive pool shell can be bonded with, so that the equipotential bonding grid created is all at the same potential voltage, ensuring the safety of those entering the pool. Without this connection, entering the pool by a metal ladder or swimming near a light housing could prove fatal. It is vitally important the pool contractor be well versed in the code requirements for the equipotential pool grid and follow the NEC guidelines to the letter to protect all the users of the pool from these dangers.