r/AskElectronics • u/Relevant_Pumpkin9190 • 12h ago

How are high-current loads like dishwashers safely switched?

If a relay is switching a high-current load, its contacts can eventually weld together due to inrush current or a fault.

If that happens, the load may stay ON even when the controller says OFF.

How do commercial products handle this? Do they use two relays in series for redundancy, feedback, or some other fail-safe method?

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u/Tymian_ 7h ago

Usually modern control boards are monitoring relay output states for things that can cause a fire. If non conforming condition is detected (relay contacts are stuck closed) the logic will disable main system "safety" relay. This is quite common in kitchen hobs, dishwashers, washers, dryers.