Safety Isolating Transformer 200 W

Safety isolating transformer, 200 W, for underwater lights in swimming pools, fountains and spas. It steps the mains supply down to 12 V through a galvanically isolated winding, so no mains potential can reach the water even if a lamp seal fails — the arrangement required by pool-lighting safety practice. 200 W carries five 36 W lamps or eleven 18 W lamps at the arithmetic limit; specify to about 80 per cent of the rating for margin, so four 36 W or ten 18 W lamps per unit. Add the lamp wattages and divide by 200, rounding up, to get the number of transformers. Install in a dry, ventilated enclosure at the distance from the pool edge that local electrical rules require, and protect the primary side with an RCD.