http://walthamstow.london/News/electrical-glass-insulators-for-power-lines-suspension-glass-insulators-for-sale/ Glass insulators have been initial developed in the 1850's for use with telegraph lines. Glass insulators for wiring started to be manufactured in the mid 1800s in response to the technologies of the time. Insulators have been first manufactured in quantity in the 1800's when the 1st telegraph and telephone circuits had been put in location. Later on when the telegraph was invented, abruptly there Sun, 19 Jan 2020 16:38:56 UTC en