By Pierre-Yves Flattot
Many pool professionals sometimes think twice about the idea of adding underwater lights to pools. In some cases, service professionals can be shocked or injured when changing out pool lights or winterizing fixtures at the end of the season.
Fortunately, inductive power transfer is now being widely used in pool lighting throughout Canada and Europe and is being produced and distributed in the United States as well. This technology allows manufacturers to provide a wireless and contactless underwater light fixture, which is relatively safer when compared to conventional lighting options currently on the market. In addition, inductive power transfer can be expanded to create an underwater electrical socket for accessories such as pool vacuums and floating sound speakers.
Induction solution
The pool industry has been facing several challenges associated with electricity in water for decades.
Some of the primary concerns are:
- Risk of electric shock;
- Difficulty of wiring through pool walls; and
- Corrosion of contacts and electrical wires due to harsh pool and spa water environments.
However, these problems can be eliminated if the electrical outlet does not come in contact with the inside of the pool or spa. In this case, power is transmitted by ‘electromagnetic induction,’ using a sealed female base housed within the wall of the pool and a male plug that is also sealed. The magnetic coupling between the wall socket and the plug solves any issue associated with waterproofing and insulating electrical layers.
What is induction?
Induction is a physical phenomenon where an electrical current is produced across a conductor exposed to a varying magnetic field rather than having electrical power transmitted over a copper wire. This magnetic field is created by the flow of an alternate current through a coil. Although there is no wire connection, electrons are moving, and current is being generated. This is not a new scientific discovery—the phenomenon was first observed in the 19th century by the English scientist, Michael Faraday, who concluded that if one creates a moving magnetic field and uses an alternate electric current, they could ‘induce’ current in a proximate coil of wire. Today, this concept is widely known as ‘Faraday’s law of induction.’ For induction to work, the moving magnetic field must be physically close to the device as the magnetic field becomes exponentially weaker with distance.
In this case, the induction pool lights have a sealed plastic exterior wall where the power source is located. This wall fits directly into the sealed power source and, when they come together, the magnetic field transmits or induces power in the adjacent light coils. As a result, when the wireless pool light is moved close to the power source, it turns on.
The transfer of energy between the base and the socket is achieved through (what is commonly known as) ‘magnetic coupling.’ The coil at the base is powered by an alternating voltage frequency. This current creates a magnetic field that passes through the inside wall of the base and transmits to the coil in the plug. The base and plug assembly essentially creates a longitudinal transformer.
The automatic power shut feature is one of the biggest advantages of the induction system. If the light or plug is not in place, the magnetic field is no longer produced, and the power is automatically shut off. This further eliminates any potential for electricity to escape into the pool; thus, reducing the risk of an electric shock. Here, the magnetic contact (reed switch) placed within the socket ignites the magnetic field and starts the power supply.
