High voltage electricity will use wood as insulators. Not sure why some of ya'll are freaking out about "fire".
Much lower risk of shorting something out using a wood frame as well.
You mean ceramic materials as isolator right?
From wiki:
"Large power transformer windings are still mostly insulated with paper,
wood, varnish, and mineral oil; although these materials have been used for more than 100 years, they still provide a good balance of economy and adequate performance."