> That's never caused any regulatory problems for Ma Bell, despite OSHA saying 50v is the cutoff. I'd be surprised if the wired phone system is not allowed to

> That's never caused any regulatory problems for Ma Bell, despite OSHA saying 50v is the cutoff. I'd be surprised if the wired phone system is not allowed to do a lot of things that would not be allowed under current codes and standards. By 1920 about 35% of US households had a phone. Upgrading all of that to keep up with evolving safety standards would probably have been way too expensive, and so I would expect that there was a lot of grandfathering.