You're right, in that, before deregulation, the telecom industry
went its own way, and (safely) used nominal 48 Vdc. The public was
marginally exposed, by being able to touch things like exposed pri-
mary telecommunication protector terminals, and PBX switchboard
plugs.
What the harmonization of the telecom and information processing
standards did was to recognize that, if telecom voltages had not
electrocuted anybody in over a hundred years, they must be safe
as used.
Sorry if that sounds like a commercial to those I have worked with
in the past.. I've been repeating it for so long, I couldn't resist
doing it one more time.
Regards,
Frank McCaughey
