How does a 3 wire 110 v. system operate??

davisrf

HI, I am just curious as to what the difference is in the older 2 wire household electrical wiring and the current 3 wire (black (hot), white (neutral) and bare copper (or green?) ground lead. Am I correct that in the old 2 wire systems that the fuse would blow only if both conductors shorted together?? And am I correct that in the 3 wire system that if either the
black or white was shorted to the ground side (for instance if a short inside an applicance put either the black or white to ground) , then the breaker would trip.?
Also, I'm confused as to why the white is always connected in the service panel to the terminal block that also has all the ground conductors attached to it. Thanks for the help, Steve

wooderson

First the bare ground is for equipment grounding only, the white neutral is a grounded conductor to carry unbalenced current back to its source, they share the same bus at the point of service entrance (main panel or disconnect) only the grounded conductor carries current back to its orgin which would be the transformer at the pole its like a big loop.

davisrf

Thank you wooderson, I understand your description as in a loop. Given that the neutral is carrying back the unbal current to the source, and is grounded, I guess that if this neutral was shorted to ground on the equipment the fuse would not blow?? If it would blow, then I don't understand why. Thanks again, Steve

slakker

If the neutral (white) was to cause a circuit to "blow" when shorted, then the circuit is likely wired incorrectly and that the white wire has somehow been tied to a "black" hot wire somewhere along the way or at the panel... If this happens, I'd recommend finding the problem and fixing it right away.

davisrf

slakker, thanks!