Hello, I've replaced a few of these over the years and have concluded that they are not up to the job. The current passing capability is not up to what a typical caravan pump needs, hence the failure history. On a failed switch, it won't power the pump but does give a low ohms reading to a meter, and even lights the "pump" led if no pump is actually plugged in. As soon as the pump's plugged in, nothing....,. So it's obviously going high resistance. Any one else had this? I contacted a caravan workshop and was told it's a known problem. But I guess they're not too bothered as it's just more income to them. Whale won't tell me anything. I'll probably just install a better quality, external switch. It's more annoying than anything else, why should Whale make money via constant replacements out of substandard performance or mismatched components?
If the current-carrying capacity of the micro-switches is not up to taking the load of the pump, I would fit a relay to take the pump load, and use the tap switches to switch the relay. Quite a simple circuit, and should make the micro-switches virtually last forever.
No not dirty contacts. The microswitches are completely sealed. I just think that because they are so very micro, after a while the contacts overheat in passing a current obviously greater than they are rated for and so eventually fail. Colin's suggestion of adding a relay is definitely a good one. It's all lead me on to ideas anyway of modifying the whole tap operation eg overcoming the constant pump operation during showers eg putting in a separate switch in place of the micro so that when the shower head is closed, I can turn off the pump as well. All very interesting stuff!