I was wondering about balanced, whole-house electrical systems. For simplicity, assume that the two sides are +60 v. and -60 v. Would the negative leg be shared across circuits the way that it would have been if it were the neutral leg in a non-balanced system?
A hole house balanced (technical) split phase system for 120vac presents a number of challenges. Specifically, it would present a danger for conventional incandescent lightbulb sockets. The outer portion of those sockets are acessable to fingers, as they're expected to be connected to the 'grounded conductor', neutral. (note, the 'grounded conductor' is not the ground conductor, the mains safety ground.) Additionally, electrical components and appliances are not typically fused or switched internally on both the 'hot' and 'neutral'. In a balanced power environment, what was the 'neutral' in a 120vac single ended system is now a 60vac line. If an internal fault occurs within the component from that unfused and unswitched 'neutral', it presents a danger. This is why NEC code calls for a technical power point of service's outlets be connected through a GFCI, ground fault interrupter. That insures that any current beyond a safety limit that is diverted (to safety ground, your body, etc....) triggers a disconnect. A disconnect will also be triggered if you connect some, more than 35yr old components that have neutral connected to chassis ground. The 'neutral' is no longer neutral, it now carries 60vac, antiphase from the 60vac now on the 'hot' line.
Balanced (technical) power is substantially the same as North American 240vac service which is used to power large appliances, stoves, air conditioners, etc.... save for the fact that its 2 energized lines carry atiphase 60vac lines (totaling 120vac), rather than N.A. 240vac whose 2 lines are antiphase 120vac (totaling 240vac). In split phase power, current flows from one phase to its antiphase counterpart, not to a 'neutral'.
