Swimming safely in a clean environment

Public swimming pools need electricity as much as water

By Morand Fachot

Public swimming pools rely on a wide range of equipment, most of it controlled electrically or electronically in one way or another. Users take a safe and clean swimming environment for granted and are generally unaware of the hidden aspects of swimming pool installations. To have a better understanding of all the systems needed to ensure hundreds of thousands enjoy a swim in the best possible conditions every year, e-tech was granted exclusive access to the technical installations of the Varembé swimming and sports centre*, near the IEC Central Office

View of some of the swimming pool electrical enclosures that control all operations

An uneasy relationship

Pool equipment and maintenance systems include a variety of devices for heating, cleaning, sweeping, pumping and lighting. They include automated systems, controllers and safety equipment. Most rely on electricity, but water and electricity have an uneasy relationship.

As risk is always present when water and electricity are in close proximity, the design and installation of such equipment and systems must meet strict criteria to protect individuals against electric shock. These criteria apply to electrical installations for swimming and paddling pools and their surrounding zones, and for basins and fountains as well as “areas in natural waters, lakes (…) specially intended to be occupied by persons for swimming, paddling and similar purposes”.

IEC Technical Committee (TC) 64: Electrical installations and protection against electric shock, developed IEC 60364-7-702:2010, Requirements for special installations or locations – Swimming pools and fountains. This Standard defines the dimensions of three zones in which such equipment may be installed and stipulates what may go where¸ as well as the characteristics of wiring and current-based equipment used in swimming pools.

Several IEC TCs and their Subcommittees (SCs) prepare International Standards for these electrical installations. They include TC 61: Safety of household and similar electrical appliances, and SC 34D: Luminaires.

Clean and clear

Cleaning of pools is essential for health reasons and to avoid contamination. It relies on mechanical and chemical processes; which are all controlled by electrical systems.

Cleaning involves constant recycling by removing debris (i.e. hair) and dirt like creams or cosmetics, from water before sanitizing it.

This is done first by pumping water from the bottom or from the sides of the pool when it overflows into channels, before sending it to sand filters, which are large tanks filled with sand that trap dirt and small particles in the 20 – 100 micron range.

Following this first treatment water goes through a UV sanitizer unit that kills pathogens, germs and viruses, and reduces significantly the quantity of chemicals, such as chlorine and bromine, needed to disinfect water. Some manufacturers claim that “savings of 70% – 85% in chlorine consumption are commonplace” when a UV sanitizer system is installed.

IEC TC 61 develops International Standards for the safety of UV equipment used for water treatment appliances.

However, after UV treatment chemicals, such as chlorine, still need adding to make certain water is not contaminated. This is done using a digitally-controlled dosing pump that ensures the right amount of chemical is continuously injected into the water before it is pumped back into the pool.

Pumps are central to a swimming pool operation. Their range extends from large pumps used to pump water out of the pool into the recycling / cleaning system, to smaller dosing pumps. All pumps in a swimming pool are electrically-driven or powered. They are also built around rotating electrical machines. IEC TC 2: develops International Standards for such machines.

Evacuating excess humidity from all areas in a swimming pool, from shower rooms to main swimming hall and other areas, and maintaining the right temperature all year long require extensive ventilation installations. IEC SC 61D: Appliances for air-conditioning for household and similar purposes, prepares International Standards for electrical air conditioners and dehumidifiers used in residential, commercial industrial and other buildings.

Lighting makes a difference, but must be safe

Lighting can enhance the swimming pool environment and overall user experience. Lighting fixtures may be installed outside the pool, above ground or recessed, and underwater in appropriate housings. Light can be delivered via a variety of bulbs, LEDs or fibre optics.

IEC SC 34D: Luminaires, published IEC 60598-2-18:1993, Luminaires – Particular requirements – Luminaires for swimming pools and similar applications. This International Standard details general test requirements, the classification of luminaires and characteristics regarding their construction. It also describes tests for mechanical strength and corrosion and many other features for light fittings that are used in the swimming pool environment.

In some swimming pools, like the one e-tech visited, a number of lighting installations have been upgraded to LED-based lamps, resulting in a significant saving in terms of energy and maintenance costs.

Cleanliness and safety outside basins are important too

Although focusing on clean water in basins and safe electrical installations in their vicinity is vital, extending a clean and safe environment beyond the pool areas is also essential.

Users enter swimming installations from what is essentially a dirty environment: streets. Maintaining all areas clean and removing excess water from floors, which is a safety risk, as people can slip and fall, requires special industrial cleaning machines, such as automatic scrubbers and vacuum cleaners that can operate in dry and wet environments. IEC SC 59F: Surface cleaning appliances, prepares International Standards for such machines.

Keeping users safe as they get ready to leave is important and is the object of special attention from staff. Drying hair after swimming is a normal activity, but the use of personal hairdryers is banned and an adequate number of appropriately designed fixed hairdryers, plugged into special sockets placed out of reach of users is available.

Sockets and light switches installed in humid areas are protected against water ingress according to international IP coding and testing system that classifies the protection by enclosures for many types of electrical equipment.

IEC TC 70: Degrees of protection provided by enclosures, "prepare international standards including appropriate test methods for degrees of protection provided by enclosures against ingress of (…) water and against access to dangerous parts".

Hidden heart of installations

As the Varembé swimming pool technical staff told e-tech: "without electricity there would be no swimming pool, it's as simple as that".

This is clearly illustrated by all the equipment and countless brightly coloured enclosures containing electrical systems that control all the equipment required to ensure that the 300 000-400 000 people who use the facility year-in year-out do so safely. Equipment doesn't tell the whole story, without the tireless attention of the swimming pool staff responsible for maintaining and operating this equipment it would quickly grind to a halt.

* e-tech is grateful to the Geneva Service des Sports and to the Varembé swimming pool staff for granting it unrestricted access to technical installations and for their assistance

UV sand filter After passing through a sand filter (left) water is sanitized inside a UV unit (right)
UV system Cutaway view of a UV sanitation unit (Photo: Delta UV)
HVAC (heating, ventilating, and air conditioning) installation Heating, ventilation and dehumidifier installation
Enclosures View of some of the swimming pool electrical enclosures that control all operations
Taski scrubber Taski Swingo battery-operated scrubber drier used to clean floors