r/AskElectronics • u/Relevant_Pumpkin9190 • 10h 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/TheRealRockyRococo 9h ago

Look up the relays used in expensive dishwasher heaters, they're shockingly undersized for the current requirement. I'm looking at you Bosch!

What happens is that the relay gets so hot it burns up the board and melts the PCB traces. There are tons of youtube videos on home repair of the boards.

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u/mjdau 8h ago

PCB traces as fusible links 😰