We just bought a house in California. Can a built in dishwasher be plugged into an outlet or must it be hard wired?
It can definitely be plugged into a receptacle. Some new dish washers come with the cord already attached and some give you directions. Almost all require a GFCI outlet and you need to read what size circuit you need.
My experience in the past 3-4 years. Installed 6 dishwashers. 1 had cord already on it - which is kind of a pain because often there is no outlet. The other 5 all had instructions that said it allowed for wiring to be turned into cord. 1 we did that because it made sense - used outlet behind fridge (not the same outlet as fridge). Just look up manufacturer's instructions online if you have any questions but the short answer is YES.
Some local codes require the dishwasher to be plugged in with the receptacle accessible, like in the sink cabinet. A dedicated 15A 110V GFCI-protected circuit is also required for most residential machines. A GFCI duplex receptacle is not acceptable since another device may be able to be plugged in, thus rendering the circuit non-dedicated.