In the TV show "Murdoch Mysteries" (S12E01) Detective William Murdoch has a an ultra-modern (for the Edwardian period) house built. It includes a "potato cooking room" which is essentially a broom cupboard sized microwave. At his house-warming party someone is found dead in this cupboard having been microwaved to death. The word "exploded" is used a few times.
My question is not whether this is feasible with Edwardian technology because I fail to see how it could be (especially considering Murdoch seems to be on a fairly standard domestic supply) but simply how powerful a microwave system would you need to cause such catastrophic damage to a human body in such a space in fairly short order (in the TV show this whole grisly murder takes place in a matter of minutes).