I went to explore the reason for a failed immersion heater. The element tested out o.k. The rod 'stat had its main operating contacts welded together and the safety trip had operated and switched the element off. I renewed the rod 'stat. Then upon turning on the 20 Amp D.P. switch with neon it flickered the neon momentarily then it died. There was a supply in from a good old 60s M.K. 20 Amp switch down stairs, still operating perfectly, but its neon is a little dim. But the newish 20 Amp D.P. switch by the immersion heater had failed after about 2 years use from new. So I found one fault, and by operating the switch by the heater that switch then failed. You couldn't make it up, and then trying to explain that to the customer isn't easy.

Has anybody else had similar experiences?

Z.