Summer is finally here! Drive through any neighborhood and it is nearly impossible to miss the signs. The smell of burgers on the grill and fresh cut grass permeates the landscape and perfectly accompanies the sound of children laughing and playing in backyards everywhere. And with summer, comes swimming. Whether it is swimming in a pool, lake, ocean, or even just playing in a puddle, children of all ages jump at the chance to head to water when the temperatures rise. But before we do, it is important for all of us to take a moment and consider the safety measures that have been put in place to ensure that an epic cannonball off the diving board does not turn into a tragic electrical accident.
In case you didn’t know, submerging our bodies in water makes us more susceptible to electric shock and reduces resistance of our skin. This in turn permits lower voltage levels to cause a sufficient amount of current to flow through our bodies, which is extremely dangerous, and possibly even deadly. For this reason, NFPA 70®: National Electrical Code® (NEC®) contains many requirements to minimize shock hazards in and around pools and hot tubs and protect us from harm. With this in mind, there are essentially two methods of protection that are employed in the pool and hot tub safety requirements of the NEC®:
- Eliminate voltage gradients in the water and surrounding areas
- Interrupt power if and when there is a problem
The first method of protection, eliminating voltage gradients, deals less with protection from faulty electrical equipment itself and more so with taking measures to electrically connect conductive surfaces and items in the area around the pool, including measures to bond the water itself to the conductive surfaces and equipment. This concept is referred to as "equipotential bonding," meaning, bonding things together in order to keep everything at the same or equal potential or voltage. The NEC requires all of the following to be bonded together with a minimum of an 8 AWG solid, copper conductor or with rigid metal conduit made of brass or other corrosion resistant material:
- Conductive pool shells, such as concrete poured or sprayed over rebar or a copper conductor grid
- Perimeter surfaces up to 3 feet measured horizontally from the inside wall of the pool
- Metal fittings
- Electrical equipment associated with the circulation system or pool cover
- Metallic components
- Fixed metal parts like ladders and handrails
- Underwater lighting
Lastly, if none of these components to the system are in contact with the actual water itself, means must be provided to expose a minimum of 9 square inches of a corrosion-resistant and conductive material to the water. By connecting all of these items together, the chance that any one of them develops a difference in potential from any of the other items or the water itself is now reduced.
The other main method for protecting people from electrical hazards in and around pools and hot tubs involves turning the power off when there is a fault or other problem. There are also two main vehicles in which this level of protection can be provided:
- An effective ground-fault current path to facilitate the opening of the overcurrent protective device (OCPD)
- Ground-fault circuit interrupter protection that monitors the current on the circuit and interrupts power when the difference between what goes out and comes back in exceeds 4-6 mA
Combined, these two methods protect pool goers by removing the electricity from the environment when there is a problem. For instance, often the area surrounding a pool is very corrosive and harsh with respect to electrical equipment and can cause conductors to loosen up or break off from their terminals. This could lead to a conductor contacting the frame of a motor or a metal raceway or side of a box increasing the chances of someone being electrocuted. Having an effective ground-fault current path like an equipment grounding conductor will help the overcurrent protective device supplying the circuit open quickly by providing a low impedance pathway and spiking the fault current high above the trip setting or rating of the OCPD. For instances where a human might come in contact with this faulty equipment, GFCI protection is required. This protection helps to interrupt the power even when the fault current isn’t high enough to trip the OCPD, which might be the case in the event that the EGC or bonding conductor has been broken or otherwise disconnected.
All these measures are aimed at protecting us in an environment we often view as recreational and relaxing. However, due to the chemicals and moisture and nature of activities that take place in and around a pool, a certain level of maintenance and care must be done to ensure that these protective measure continue to function and provide the intended level of safety. This is where both qualified electricians and pool owners can work together. Regular testing of GFCI receptacles and circuit breakers is needed to verify that these devices will operate when the need arises. Regular inspection of grounding and bonding conductors is also a must to make sure that these needed pathways are still in place both to open the OCPD when equipment fails and to eliminate dangerous voltage gradients that could lead to electric shock drowning or electrocution.
Staying safe in and around pools from electricity is often not the first thought on our minds when the temperature climbs and we head poolside to relax and unwind. But with a little attention to maintenance and inspection of the measures put in place at the time of installation, we can do that cannonball without a second thought.
So now that you’re aware of how pools are built to protect you from electricity (even if you don’t understand all of the requirements) remember to work together with a local qualified electrical who can help you with maintenance and inspections, and can answer any questions you may have. Then kick back and enjoy your time around the pool this summer knowing you’ve put safety first!
For additional pool safety tips, resources and information, check out NFPA’s website.