Re:Why we ground electrical systems (2015)
by jessaustin on Friday August 02, 2019 @05:12PM
(#20596691)
If you don't bond neutral and ground at the main, it's still bound at the transformer.
That would be a pretty good trick. The transformer is outside my house on a pole. Two wires run to it, the hot and the neutral. The "ground" doesn't leave the house. (Other wiring schemes exist, but this is standard USA residential.)
[EDIT: brainfart, see helpful correction below. still no "ground" at the pole...]
> still no "ground" at the pole...
Yes there is. The neutral is bonded to ground, via an actual metal pole in the ground.
In your house is the same thing: The neutral (and the ground) and attached to a metal pole in the ground.
And the earth itself completes the circuit.
Re:Why we ground electrical systems (2015)
by jhayward on Friday August 02, 2019 @05:21PM
(#20596754)
> Two wires run to it, the hot and the neutral
Standard US residential is 240V split phase, with two hot and one neutral conductor from the transformer. So three wires, minimum. Unless you have a very old feed.
Re:Why we ground electrical systems (2015)
by jessaustin on Friday August 02, 2019 @05:26PM
(#20596798)
Ah, yes, well spotted. That was an oversimplification. Two hots, one neutral, zero "grounds".
If you don't bond neutral and ground at the main, it's still bound at the transformer.
> then the current will flow through the ungrounded conductor,
No, it will flow through the grounded conductor.
> back to the source (usually a transformer), across the windings, and eventually back to the breaker that controls the circuit
The flow of power is the same via ground as it is via neutral.
> This will build up enough current (usually VERY fast, like milliseconds)
There is no such thing as "build up enough current", current does not "build up".
The milliseconds has to do with built in time delays at breakers, it's not a function of the electricity.
> The Earth has nothing to do with this
The actual Earth is used as a conductor, so yes, it definitely has something to do with this.