In my rig there are two switches for the pump, one in the bath and one in the kitchen. These switches do not have a typical on – off configuration. If both switches are in the same position the pump is on, if one is in the opposite position from the other, the pump is off. There are two places where we have water, the kitchen and the bathroom. Therefore, there are two switches for convenience. The OEM of the witches is Sigma and has the same dimensions as RVD and DG switches and they are fully interchangeable.
Below is a diagram of the circuit, and general information on the switches including the part numbers. If it would be helpful, I can scan the pages from the catalog and post them. Just notify me by PM.
I see by your last post that you have decided not to add the second switch, but should you change your mind, it is a pretty easy mod.