2015 IRC E4204.2 refers to bonding together of different elements related to swimming pools but bonding isn’t required to connect to a remote panelboard, service equipment, or electrode. Is this because one or more of the elements required to be bonded will act as an electrode?
I thought that if voltage got onto any conductive elements, that bonding together of multiple elements plus their connection to ground would reduce the potential for shock/electrocution. If there’s no connection to ground, doesn’t that just energize everything bonded together?
If all those things bonded together are energized, how does that make things safe? If one of them becomes energized, now they all are. If they’re bonded and connected to a breaker and also grounded then the breaker is likely to trip, but if they don’t have to be connected to a panel or electrode, how are they all protected?
The pool equipment is bonded to the panel via the EGC run with the branch circuit to the pump. All of the metal parts are bonded together via the equipotential bonding conductor that also connects to the pump. That is why you do not need to run a bonding jumper all the way back to the panel.
“The purpose of bonding is to connect metal parts together so that if one part becomes electrically energized its voltage will not be different from any nearby metal part. If metal parts are at different voltages, a person touching one part could become the electrical path to ground if he touches a nearby metal part. Bonding and grounding are not the same. Bonding connects metal parts to each other. Grounding connects electrical equipment to an earth grounding point. Note that some metal parts, such as pool circulation equipment, must be both grounded and bonded. In this case, the grounding wire is usually contained in the electrical wires serving the equipment and the bonding wire is usually connected to the metal exterior of the equipment.” Bonding of Metal Near Swimming Pools and Spas.docx (12.9 KB)
To understand potential, imagine how water flows through a pipe. It will naturally flow from an area of higher pressure to an area of lower pressure. If both ends of the pipe have equal pressure the water will not move, regardless of the level of pressure.
Electricity works in the same way. There has to be a difference in pressure (or voltage) to create a flow of electricity from one point to another.
The purpose of equipotential bonding is to equalize the pressure around the entire pool so your body doesn’t create the circuit between areas of differing potential which would result in getting shocked.
The barehanded approach has a live line worker performing the work in direct electric contact with live parts. Before contact, the worker’s body is raised to the same electric potential as the live parts, and then held there by electric connection, while maintaining suitable isolation from the surroundings which are at different potentials, like the ground, other people or trees. Because the worker and the work are at the same potential, no current flows through the worker.
It’s silly for such a small piece of metal but the NEC doesn’t have an exception for small fixed metal parts. Funny thing is for metal fittings that are not over 4" and penetrate into the pool structure by 1" or less bonding would not be required. {680.26(B)(5)}