Pool and outdoor electrics in San Vicente del Raspeig

San Vicente is inland enough that salt is not the dominant problem it is on the coast.

What replaces it is damp, and it concentrates in a single place: the filtration plant room.

Why the plant room is wetter than the pool

A filtration plant room is usually built partly below ground so that the pump sits below the waterline and stays primed. That is sound hydraulic design and a poor electrical environment, because a room below ground level is a room that collects water and never dries.

Three sources contribute. Groundwater and rain find their way in through the structure. The pump and its fittings weep small amounts continuously, which is normal for a pump and abnormal for an electrical enclosure sharing the room. And because the space is unventilated and cooler than the air outside, humid summer air entering it condenses on every cold surface, including the inside of a panel.

That last one is the mechanism people miss. A panel can be perfectly sealed against splashing and still fill with condensate from the inside, and it corrodes from the back where nobody looks. The first symptom is usually a nuisance trip that gets reset for months before anyone opens the enclosure.

What actually helps is unglamorous: ventilation so the air changes rather than stagnating, enclosures mounted clear of the floor and on the driest wall, glands entering from below so water cannot run down a cable into a box, and a drain or sump that works. None of it is expensive. All of it is routinely absent.