Lighting inside the water is the most sensitive part of a pool's electrical installation. That's why Spain's Low Voltage Electrotechnical Regulation, in instruction ITC-BT-31, only allows safety extra-low voltage inside the pool: 12 V AC or 30 V DC, with the power supply outside the pool zones.
12 V inside the water
Why LED pays off
- Power use: a classic halogen light (PAR56 format) is usually 300 W; equivalent LEDs use, depending on the model, a small fraction of that.
- Lifespan: they last much longer than a halogen lamp, so they need changing far less often.
- Less heat in the light and its seal.
- Colours and scenes, if you want them, by remote or app.
In many cases the PAR56 lamp can be replaced by an LED of the same format without building work, using the same niche. You need to check it's compatible with the existing transformer.
What electrical safety requires
| Zone | What ITC-BT-31 says |
|---|---|
| Zone 0 (inside the pool) | Safety extra-low voltage only: up to 12 V AC or 30 V DC. |
| Power supply (transformer) | Outside zones 0, 1 and 2. |
| Zone 1 | Up to 2 m from the pool edge and 2.5 m high. |
| Underwater lights | IPX8 protection, in line with UNE-EN 60598-2-18. |
How to change a light (PAR56 lamp in a niche)
- Switch off the lighting circuit at the panel.
- Release the trim and take the light out of its niche. If the cable has slack, it can be lifted to the edge without draining the pool.
- Open the light and replace the lamp with the new one, connected the same way as the old one.
- Check the seal and replace it if it's hard or deformed: it's what keeps the water out.
- Close it firmly, refit the light in the niche and restore the power.
If there is water inside the light, the cable is damaged or the RCD trips when you switch it on, don't reconnect it: have a professional check it.
Frequently asked questions
Can I put any LED in a pool light?
No. It must be a pool lamp, submersible (IPX8), at 12 V and compatible with the existing transformer. Ordinary lamps aren't designed for water.
Do I need to drain the pool to change a light?
Usually not: with niche lights, the cable normally has enough slack to lift the light to the edge. If it doesn't, the water level must be lowered below the light.
Why does the RCD trip when I switch on the lights?
It usually means current leakage: water inside the light, a damaged cable or a transformer problem. Don't keep trying; call a professional.