WATER WAYS

Between heat, damp, corrosion, chemicals, glare and the need to be ensuring public safety at all times, illuminating swimming pools and wet areas can be challenging

By Roger Beckett

It is no secret that wet area lighting is a specialised arena, one where the decorative and the functional combine to create the remarkable.

The latest innovations from manufacturers, coupled with in-depth photometrics, performance reviews and analyses and, of course, LED technology, now means it is easier than ever to create the perfect scheme.

In fact, whereas it used to be the case that strip-out-and-replace was about the only option for regenerating tired wet and underwater areas, nowadays it is becoming increasingly straightforward simply to retrofit older projects, so as to give them a new lease of life and enhanced efficiency at a fraction of the cost.

The starting point when thinking at wet area lighting is BS7671:2018, the eighteenth edition of the wiring regulations [1]. These address swimming pools, regardless of which zone you’re working within, and cover the correct specification of fittings and the best (and most robust) designs suitable for areas of humidity or corrosive environments, for example, spas and saunas. Bear in mind that public pools

Figure 1. This graphic, from BS7671, shows some of the different zoning issues you need to consider when lighting wet environments

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Lighting underwater and wet areas

also usually have a higher concentration of chlorine, which is of course highly corrosive in itself.

Another issue to consider is that, as advances in lighting keep accelerating, it is often hard to stay up to date with the latest products, especially given the fast pace of LED product innovation. You also need to keep abreast of the performance of fittings and how this is developing as, when they’re used underwater, there will be associated, and often complex, issues around refraction and other unique challenges.

We all know that great underwater lighting is a combination of four key elements: colour, control, intensity and direction. This, coupled with the correct use of colour temperatures, is the cornerstone of every project.

When it comes to underwater and wet area lighting, the recommended colour temperature range for underwater lighting is 3000K to 6000K, with cooler colour temperatures complementing the water surface and reducing glare, as shown in figure 2. The Society of Light and Lighting (SLL) also recommends at least a 60 CRI for most water-sport applications [2].

Lighting professionals may also be able to ‘lean’ on the expertise of manufacturers in this area. For example, at Wibre we’ve recently launched an IP68 Lighting Tools brochure. This is complete go-to guide to effective lighting – including outlining a framework for project design and installation – on everything from the smallest of plunge pools to Olympic-sized swimming pools, fountains and amenity lighting. Check out the end of this article for more details on this if of interest.

Typically, fittings for this sort of challenging environment will need to be able to accommodate:

• concrete pools with tile covering • foil-lined pools (pressure flange) • thin-walled pools (pressure flange) • pools with adhesive/foil coating (adhesive flange) • stainless steel pools facing concrete pools

For smaller pools, in other words up to 3m-4m wide, it is best to choose a single-sided arrangement or offset positioning of the spotlights on both sides. We’d

Figure 2. The recommended colour temperature range for underwater lighting is between 3000K to 6000K Figure 3. Some effective lighting schemes for small and organically shaped or curved pools

Figure 4. Examples of single-sided and offset positioning, which can often be effective in larger pools

Figure 5. An example of an opposite parallel lighting scheme, as often used to illuminate competition pools

Figure 6. Diagonally offset lighting. This can often work well in the biggest sports’ pools

Lighting underwater and wet areas

Figure 7. Reflectance of a luminaire, walls and ceiling on the water’s surface, and showing calm versus turbulent

also recommend one spotlight for every 2m of pool length. Organically shaped, or curved, pools show the best effect with an even arrangement of lights. You can see examples of all these in figure 3.

For larger pools in standard sizes, in other words from 4m wide, choose a single-sided arrangement or offset positioning of the spotlights on both sides. For this sort of size, the number of spotlights depends on the pool length, but one spotlight per 2m-3m is recommended. Figure 4 shows some examples of these.

Carrying on up the size range, for even larger pools, from 8m wide, but still of standard size, it is best to choose an opposite arrangement of the spotlights, with a distance of approximately 3m between each. This, again, determines the number of spotlights per pool length. The positioning can be parallel or offset. For narrower pools, a one-sided arrangement is practical and can often look very effective. When it comes to the largest pools, competition pools we’d recommend you choose an opposite parallel arrangement to illuminate optimally. A total of 12 spotlights per pool length is recommended here. You can see an example of how this might look in figure 5.

For sports pools, which normally are 25m x 12m, an effective design is normally eight spotlights per side. The positioning can also be done in a diagonally offset way, as shown in figure 6.

With all the above, once the layout has been considered, correct specification of fitting is just as important.

The wattage of the LED, obviously, dynamically affects the whole installation.

For smaller pools, IP68 recessed spotlights can be used with minimal 1 POWLED and lumen output up to 675lm. Fitting size and output then exponentially increases all the way up to competition and sport pools, where you need up to 18,600 lumen light intensity.

It goes without saying that, with all pools, safety as part of the design is a critical factor. It is imperative to prevent surface glare, especially in public pools. Glare is often cited as one of the key contributory factors to accidents. Therefore, regardless of whether it’s reflected glare from external light sources or windows, a zone visibility test is paramount in ensuring the safety of all users.

Frequently a glare pattern analysis can be used to help mitigate concerns. Glare on a swimming pool surface is a common concern, with natural or artificial light reflecting off the surface. This can cause discomfort to swimmers as well as being a serious safety concern, as lifeguards can struggle to see swimmers should they be in need of assistance. It also stands to reason that managing the underwater lighting and putting in place the most effective scheme can help mitigate these issues. Figure 7 above illustrates some of the challenges around reflectance that can be posed by this sort of environment.

The Royal Life Saving Society UK is an excellent resource for managing health and safety in swimming pools. Another is the SLL Lighting Guide and its infographics [3].

Luminaire selection, naturally, is a further vital consideration in an wet area or underwater scheme. You should consider access requirements for maintenance and cleaning as well as:

• Replacement of LEDs • Replacement of drivers • Reusing the same niche • Ease of access of cable • Long cable runs (up to 100m) • Deck boxes

We’d advise positioning fittings 0.5m and 0.70m under the surface so that swimmers are illuminated.

Placing fixtures on the long side of a pool also ensures beams need to travel less distance and, so, cause minimum annoyance to swimmers. This means the bright beams pass the shortest distance through the water. This normally provides enough inter-reflection to light the sides and bottom of the pool.

A further consideration here is the issue of the viewing angle. You want to place fixtures away from main viewing aspect, ideally; end users should not have a direct view into luminaires where possible.

A BRIEF WORD ON FOUNTAINS

When it comes to lighting fountains, less can be, and often is, more. There often seems to be a tendency of over-illumination of fountains when, in fact, cleverly placed quality fittings are better than quantity, regardless if remote or located in the water.

Fountains and waterfalls work best when droplets ‘catch’ the light. This is achieved by positioning spotlights in the water. A common technique is to locate spotlights alongside water jets.

For smaller fountains, or those with a water height of up to 2m and at 675 lumens, a surface-mounted spotlight is perfect. You want to be sure that it will be fully adjustable (ideally through 90°) and that, of course, it is IP68-certified for submersion in up to 3m of water, plus that it can be controlled externally. For medium-sized fountains (from 2m-10m high), surface-mounted spotlights are the way to go, and we’d recommend that 2,300 lumens is ideal.

They’ll need, again, to be fully submersible, unless they’re highlighting individual objects or architectural features. Ideally, again, you should be looking for a product that is adjustable through 90° and which offers rotationally symmetric light distribution.

Finally, for large fountains (up to 25m in height), we’d recommend going for surface-mounted spotlights, ideally at 4,600 lumens, although for the largest

Specialist ‘donut’ fountain fittings. These can be installed on the water jet to allow the water to pass through

Lighting underwater and wet areas

installations (which can get up to 50m high) you might be looking at lighting more in the range of 18,600 lumens.

The positioning and number of spotlights will, of course, depend on the style and desired result. But the rule of thumb is that the closer the spotlight, the more intensive and accentuating the illumination. Fibre optics, too, are becoming an increasingly popular source for wet area lighting, and so may be something worth investigating.

Roger Beckett is R&D and sales development director at Light Projects

Illustrations of varying underwater lighting schemes, as carried out by Light Projects HOW MANUFACTURERS CAN HELP

As mentioned in the main article, Wibre has recently launched an IP68 Lighting Tools brochure to help lighting professionals get the best results when it comes to wet area and underwater lighting.

To find out more about this or get hold of a copy, go to: https://lightprojects.co.uk/ wibres-new-ip68-lighting-tools-brochure/

In terms of products, it goes without saying that our ranges are extremely well-suited to this sort of challenging environment, and so speaking to a specialist manufacturer can be a great starting point..

ILP members will obviously want to do their own research, but we’d argue that, for smaller pool areas, our 12V-DC fittings are a small and neat solution, whether monochrome or RGB dynamic.

All Wibre fittings come in the spectrum of colour temperature most suitable for wet areas (to recap, from 3000K to 6000K) and in different beam angles from narrow spot to wide flood. RGB versions can also be supplied with dynamic illumination and colour changing. We also have a ‘Mixflux’ variant which features an asymmetric optical array, which sits inside the fitting, to illuminate the full body of swimming pools.

For fountains, we’d recommend our 4.0050 surface-mounted spotlight for smaller fountains, with the RGB option especially good for ‘feature’ fountains. The 316 marine-grade fitting also ticks the various boxes discussed in the main article, namely that it is fully adjustable through 90°, IP68-certified for submersion in up to 3m of water and can be controlled externally.

For medium fountains, we’d recommend our 4.0100 surface-mounted spotlight and our 4.0290 for larger fountains and our 4.0490 for the biggest installations.

[1] BS7671 – 18th Edition, The IET Wiring Regulations, https://electrical.theiet.org/bs-7671/; plus NICEIC, ‘18th Edition Wiring Regulation – certification key timelines’, https://www.niceic. com/media/news/niceic-18th-edition-wiring-regulation#:~:text=The%2018th%20Edition%20of%20the,new%20version%27%20before%20that%20date. [2] SLL lighting publications, https://www.cibse.org/knowledge/sll [3] Royal Lifesaving Society UK, https://www.rlss.org.uk/; SLL lighting publications, https://www.cibse.org/knowledge/sll