I always thought AC current requires 2 wires to carry the current both ways just like DC. Recently I read a post on this sub saying neutral wires go to ground. What am I missing?
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Ground wire is for safty features, dissipate to the ground overcharges in the circuit, you can live without, but better have it.
DC common goes to ground as well. In single phase power systems ground is always the reference. In multiphase or split phase systems things become more complicated.
Any circuit requires two “wires”, whether it’s AC or DC…one to deliver current, one to take it away. In DC, the current is always going the same direction in both wires. In AC the current oscillates back and forth.
The “ground” in an electrical sense is just one big shared wire. The “hot” wire in an AC system is the one that actually goes back to the generator. The neutral wire isn’t hooked directly to the generator, it’s just hooked to ground and all the AC circuits are sharing that same ground (including the generator).
Neutral and ground are also grounded to the earth via a grounding bar. It’s a metal spike that is driven into the ground. Turns out, the earth is conductive.
The neutral and the ground in your house are tied together where electricity enters the home, then that is tied to earth ground. The reason they are separate in your house is so you have a separate safety circuit in case the insulation in one of your electric devices fails.
If you’ve ever touched a pinball machine, drink machine, or any other energized metal equipment and got shocked; that would be why the earth ground is added on top of the AC Neutral.
In australia the neutral is connected to ground at the switchboard via an MEN link, and at the transformer by another MEN link.
If your supply Neutral is faulty on your installation, say from the pole to the building then the MEN link allows the return path to the star point on the transformer.
Yes your neutral is at the same potential as earth.
Power lines don’t have a neutral wire. They have three wires with current being 120 degrees out of phase between them. So when on one wire the current goes “full forward”, it goes “half back” on both of the other two, and so on. So the current is always going in a circle, but that circle is being continuously shifted around those three wires. This arrangement is highly efficient in terms of conductor usage and is easy to adjust in terms of voltage.
Neutral is required for the single-phase power that we have at home. That neutral goes back to the electrical transformer where it’s usually grounded for stabilization purposes.
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For background I’m an electrical engineer.
You’re right, “neutral” is technically ground.
Most homes have 3 wires on their outlets: live (or line), neutral, and ground. Electrical current comes from the live wire from your electrical panel and goes back through the neutral wire back to your electrical panel (usually tied to a big metal bar in your electrical panel called a ground bus). These two wires are connected to the power lines running into your house from the power plant. Under normal operation, this is sufficient to complete the circuit and deliver power to where you want it.
The third wire, ground, is for safety purposes. This wire is tied to a ground bus or metal spike separate from your electrical panel. Spikes in current or voltage will want to go there so it doesn’t damage your electrical panel or the power lines coming into your house.
The live and neutral wires come off of the power lines delivering power to your house, while the ground is specific to your house to protect your panel and the power systems coming from the power plant in the event a power surge happens.
It might help to know that 120v electrical systems on Naval and commercial vessels work exactly the same as your home, but do not employ a neutral. This is for reliability. If any part of the system becomes grounded, it will still function. The grounded side becomes a sort of neutral conductor. This is known as an ungrounded electrical system. That doesn’t mean there isn’t a separately derived ground wire.
No, power always wants to try to go back to the source. It will use a ground path, but in the case of AC power, it’s trying to find its way back to the transformer, a la neutral. Neutral is just the center point (tap) on the transformer.
Ground is only there in your AC circuits to protect the equipment in case of a fault. It’s there to provide the fastest, least resistant path back to your panel to facilitate tripping of the breaker/fuses as QUICKLY AS POSSIBLE. Poor grounds mean slower tripping or not at all.
Source: NEC, Mike Holt, https://youtu.be/mpgAVE4UwFw -1:00 in
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