Even Farther Off Topic...

www.ci.nyc.ny.us/html/dot/html/bridges/bridges/macombs.html mentioned being powered by two 2-phase motors, but link is dead.

www.nycroads.com/crossings/macombs-dam/ doesn't talk about motors.

Looks like many 2-phase motors were 4-wire, nominally 220-240 volts across opposite phases {for 90° displacement.} Probably usually grounded at the neutral point for “5-wire”...but there were likely ungrounded versions, too. Can you imagine floating pairs of voltages to ground, and maybe even pairs of connections floating with respect to adjacent terminals, too?

Musta' been cool! <What this has to do with 2-gang boxes and 310 volts I'll never know.>



[Linked Image from 67.115.161.42]




[This message has been edited by Bjarney (edited 05-20-2002).]