Every year people die by electrocution, and some of these incidents are associated with pools. In fact, In September 2016, a young girl working as a lifeguard at a swimming pool in North Carolina lost her life when she was electrocuted as she entered the water. So let’s talk a little bit about this, and how we might reduce the risk of electrical injury associated with pools.
Electrical energy acts a lot like other sources of energy in that it moves (flows) from one area to another when there is a “potential difference” in the voltage of those areas. Like a waterfall plummeting from a high point to a low point, so does electricity from a higher voltage (a live wire or battery terminal for example) to a lower voltage (ground).
Electricity generally speaking, needs a “conductor” to move or "flow" through. This flow of electricity is expressed in terms of Amperes or Amps. Some things are better conductors than others. Copper, aluminum and gold are excellent conductors and pass electricity, while things like the human body are less apt as conductors, but can certainly still pass electricity. Other substances like some (but not all) polymers and glass are insulators. Still others are classified as semiconductors (like doped / contaminated silicon). Uncontaminated water is actually an insulator when pure (distilled), but becomes sort of a semiconductor most of the time. In pools, it is usually a pretty fair conductor having been “contaminated” with minerals, chlorine and sometimes salt. The human body is a mediocre conductor, but also a poor insulator. Being that we are largely made up of contaminated water, electricity from a source will pass through our bodies on the way to ground…the lower voltage. On the way through it can interfere with nerve impulses including those activating the heart, and cause damage, seizure or in the worst case death by cardiac arrest.
So how can we make the seemingly unsuitable bed partners of pools and electricity less…shocking?
BONDING AND GROUNDING
Bonding refers to bringing all of the conductors around the pool (the reinforcing steel, handrails, light fixtures, pump cases etc.) to the same electrical potential by connecting them all together with a conductor (a ground wire). This eliminates the possibility of any potential difference between these various items; whatever voltage one item is at, the same voltage will be seen at all of the other items. But bonding alone does not render the items safe. You can’t get a shock between one item and another, but what if a stray voltage is energizing the bonding wire to some higher voltage? Then any of the items could give you a shock if your body is grounded (for example, being barefoot on the deck). To ensure the items are a zero volts, the bonded items have to be grounded. This simply involves running a wire from the bonded loop to the ground lug in the distribution panel.
KEEP ELECTRICAL ITEMS AWAY FROM THE POOL
It is never a good idea to have an electrically powered item near a swimming pool. Things like radios, blenders (for those summer margaritas) if dropped into the pool, can electrically charge the water and potentially shock bathers. Even if the device is away from the pool on the deck somewhere, someone who has recently been in the pool could drip water into the device and create a conductive path with the water from the device, through them to ground…not fun!
USE GFCI DEVICES AND BREAKERS
Ground Fault Circuit Interrupting (GFCI) devices work by comparing the current flow in the hot (supply) wire to the current flow in the neutral (return to ground) wire. In any circuit, the current flow should be the same in both ‘legs’. If it isn’t, it means the current is going somewhere else - like through you! The GFCI device will trip to disconnect the power supply if there is a difference of 6mA (that’s 6/1000 Amps), and does so in a fraction of a second to protect us from being shocked. GFCI devices are a great way to protect people from any electrical device, but are particularly appropriate for things like underwater pool lights where electricity is so close to the water.
PERFORM REGULAR ELECTRICAL REVIEWS
It’s a fact of life on this planet of ours that things change, materials degrade, corrode, erode, oxidize and just plain wear out. Your electrical system is no exception. Electrical distribution boxes and the breakers within become corroded and fail. Plastic wire insulation dries out and cracks, ground points become corroded. Corrosion is exacerbated by exposure to salt water because of its electrolytic properties. Having a reputable electrical contractor visit the site periodically may flag some of these issues before they become a health and safety concern. In addition to a visual inspection, they can perform tests (like high voltage meggering) to assess the condition of various electrical insulators in the system.
Be safe, swim happy!