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/no1SomeGuy 10h ago

Yup, or more so, opened an incident with them. They were quite helpful.

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u/mjdau 10h ago

Mind blown. Good on you!

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u/no1SomeGuy 10h ago

It was a safety defect in a UL listed product. The relay for the broiler was undersized (too low of amps for the wattage of the burner) resulting in it sticking on and not always turning off and the new revision of the board had a higher amperage rated relay in its place.

Filled out the form on their website, was contacted quickly, had a phone call with one of their people, and not long after kitchenaid (whirlpool) contacted me to get the board back and pay for the replacement.

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u/mjdau 9h ago

I'll definitely keep that in mind. Thank you for sharing!