What kind of electrical wire type and tubing do i need if i want to bury it?

I'm moving my a/c unit from one corner to other corner, so everything has to be buried underground, electrical and a/c tubing. I'm not doing the a/c freon part but only the electrical and just want to know what kind of wire type or gauge and if it needs to be inside some sort of pipes or tubes? thanks. I live in Riverside County, CA.