Bare live wire in the dirt

[betonbill]

Does your electric company have someone to come out and analyze your usage? They also usually do comparisons of your house’s electrical usage versus other comparable houses. They should be able to answer some of your questions.

[Crafter_Man]

@engineer_comp_geek

Back in the early days of electricity, there were even some electrical power systems that only ran one wire out and used the earth as the return (hey, saves you half of your wiring, and miles of copper wire ain’t cheap). This worked well in some areas and poorly in others, and often varied depending on rainfall. That unreliability is why we don’t do that these days (plus safety issues).

It’s true that using the earth as the sole return is not used much nowadays. However, with all modern grid systems, the current going back to the power plant takes two parallel paths: 1) the aluminum neutral wire, and 2) the earth.

[jjakucyk]

@Crafter_Man

It’s true that using the earth as the sole return is not used much nowadays. However, with all modern grid systems, the current going back to the power plant takes two parallel paths: 1) the aluminum neutral wire, and 2) the earth.

I don’t think that’s the case. The wire neutral is the return, it’s just that in the electric distribution system the neutral wire is also grounded in multiple places instead of having a separate ground wire like you have inside buildings. That saves on distribution wiring and provides the same amount of safety. Current isn’t expected to flow through ground since the impedance of the wire is lower, but it could in the case of a malfunction. It gets more complicated in 3-phase transmission situations, but generally the ground is only used to drain current spikes and compensate for other fault conditions.

[Crafter_Man]

@jjakucyk

…in the electric distribution system the neutral wire is also grounded in multiple places…

Exactly. Which means the earth is in parallel with the aluminum neutral wire.

Now, you could certainly argue the resistance of the neutral wire is much lower than the resistance of the earth. However,

1. I am not sure if that’s true. While the resistivity of dirt and clay is much higher vs. the resistivity of aluminum, the equivalent cross-sectional area for the earth return path is much much greater than the cross-sectional area of the neutral wire.

2. Even if it is true, it doesn’t mean there’s 0 A flowing through the earth; it simply means the magnitude of the current on the neutral wire is greater than the magnitude of the current in the earth.

[jjakucyk]

Yes earth is in parallel with the neutral wire, but except in a “single wire earth return” situation where there is no neutral wire, little to no current flows through the ground since electricity takes the path of least resistance, and the ground is never as good as a wire. You seem to suggest it might be something like a 60/40 or 70/30 kind of relationship, but in reality it’s more like >99%/<1% if that. Any significant current flowing through the ground would cause corrosion of metal pipes, such as gas and water lines (while this is much more pronounced with direct current, such as from streetcars and light rail, it does happen with alternating current as well), and it would just as likely interfere with telecom wires that are more often buried even where electrical infrastructure is still overhead.

[Crafter_Man]

@jjakucyk

Yes earth is in parallel with the neutral wire, but except in a “single wire earth return” situation where there is no neutral wire, little to no current flows through the ground since electricity takes the path of least resistance, and the ground is never as good as a wire. You seem to suggest it might be something like a 60/40 or 70/30 kind of relationship, but in reality it’s more like >99%/<1% if that.

And you be correct; I don’t know what the typical split is, and am too lazy to Google it. I was simply pointing out the current through the earth is not 0 A for all electric grids.