Ground wire share

Answer 1

That's not much of a question but I think you mean "how or why do you share a neutral?" A neutral is sometimes called a "grounded conductor" because it is connected to the main ground at the point of entry of a home or building. But it is not the "ground". You typically have 4 main conductors at the point of entry of your home or other building. 2 are "hot" wires, 1 is the neutral(these three come from the utility provider) the last one is the ground wire(s) usually coming from ground rods pounded into the earth outside (sometimes there is also a conductor connected to the copper water pipe where it comes into the home or to a rebar encased in the concrete foundation of the building)(these are all considered the "grounding electrode conductor" or ground) the neutral and ground are connected at one point only usually in your panel but sometimes in the meter-base. there is approx. 240 volts potential between the two "hot" wires. Both wires are approx. 120 volts each to the neutral. each "hot" wire is also known as a "phase". If you could see the electrical panel with no breakers in it you would notice that one "hot" wire (or phase) feeds half of the breaker spaces and the other "hot" wire feeds the other half but the panel is not split up as it might look (left and right halves). Each phase feeds every other space vertically. So the top two breakers would be fed from "A phase" then the second two by "B phase" and so on down the panel. (this allows a double wide or 2-pole breaker to span both phases and feed 240 volts to your electric range or dryer). Now to your question: Due to the way Alternating Current (AC) is generated, the two phases are polar opposites of each other. When "a-phase" is at it's peak, "b-phase" is at it's lowest point. The neutral corresponding to it's phase conductor follows this pattern. As long as the two circuits are on opposite phases, those two circuits can share one neutral conductor with no overloading problems. If you share one neutral with two circuits from the same phase, you will over-load that neutral and it could create enough heat to potentially cause a fire. There is no over-load protection connected directly to the neutral. Electricians share neutrals for a few reasons. It eliminates wiring costs and also reduces the number of conductors in conduits. You will have problems if you try to share a neutral on circuits requiring GFCI or Arc Fault protection. It causes nuisance tripping and major headaches for all. Sharing neutrals has been a common practice for years. In three-phase systems(common in commercail and industrial buildings), three circuits can share one neutral as they are 120 degrees from each other.(picture a round generator of 360 degrees total).