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I have restored a couple of the Philco Seventeeners with hot chassis. They have a system of screws into insulators to prevent the metal cabinet from becoming hot. It is a risky arrangment. Some of these even have metal knobs, I do not remember how these are isolated.
I have also restored some 17 inch Hoffman "Easy Vision" sets that have filament transformers, but used voltage doublers for the power supply, leaving the chassis hot. They used fiber connectors, fiber mounts, etc. on the front controls to reduce the risk of shock. However the controls on the back were not insulated, kind of risky if you ask me.
However, the worst design relating to this is some of the 1940s AC/DC radios that I have. No isolation at all. If you pick it up while it is plugged in, the screws on the bottom holding the chassis in the case could be hot. Things were very different back then.
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