I opened a 35 year old residential panel the other day and there was a device mounted to the inside wall of the box. It was a glass tube, about 1" diameter, 2-3" long. Brown material inside the glass with some information printed on the side but too worn to read. The leads at each end were connected across the 30 amp 240 volt dryer circuit. I haven't seen one before. I'm thinking surge protection. Anyone know what it might be?
There was about 2 decades ago what was called a "polarizer" claiming to be able to remove static cling to clothes in clothes dryers. This device was connected between the two hot leads of a dryer breaker. This may be what your divice is or was. In my opinion it was a gimmick to sell, but some swore by polarizers.