Hi,
I need to connect a single-phase load to one of two available 400VAC phases. Permanent on state is a safe condition, the load behaves like a light bulb. Therefore, simple contact welding is not a safety hazard. Perhaps the only catastrophic scenario would be a short between the phases. Will a regular SPDT relay with sufficient dielectrict strength do or do I need a special relay? In other words, is it realistic that the contacts become welded in such a way that energizing/de-energizing the coil would bend the contact block sufficiently to cause an inter-phase short, either metallic or via plasma arc?
We are speaking of 3A semi-resistive load and the switching is rare.
Best regards, Piotr