humidity control and house fires

[Michael Gamble]

Hello List et al
I frequently come across a piano heater - really ancient - which is simply
an insulated element which has been attached in a zig-zag configuration to
the back of the "knee-board" There is a round three pin socket (male) let
into the panel. I have never come across one working though. The length of
that element is such that the configuration takes up at least ten
side-to-side (or end-to-end) stretches across the back of the knee-board.
This is the sort of heater which could cause fires....
Regards
Michael G (UK)