What does a neutral do?
In: 150
So there’s something called a transformer outside your house, they often look like garbage cans at the top of poles or weird, humming boxes on the ground. Those take the high voltage from the wires that bring power from the station and convert it into something reasonably safe to have in your home, lowering the voltage.
You have two wires that are “hot” coming from the transformer and they, in Ontario at least, have a voltage difference of 240 volts. One could be considered to be +120 and the other -120, for a total difference of 240.
But you don’t need 240 volts to power most things in a house. It creates an unnecessary risk of death or serious injury.
And thats what the neutral is for. It’s connected in the middle of the transformer and has a value of 0. If you connect one of these hot lines to the neutral wire, you have a voltage of 120, which is relatively unlikely to kill someone.
But if you do have something really energy intensive, like an air conditioner, you can connect it to both the hot wires and get a bit of extra power. And that’s reasonably safe because people are less likely to mess around with an a/c unit than change a light fixture.
And the wires also switch which is positive and negative really quickly, tho that’s not directly relevant to the question
Electricity works like a water wheel. It’s not that the electricity is consumed by your light, it’s that the electricity flowing THROUGH you light causes power. The electricity in the overhead wires REALLY wants to go to the ground, but it can’t get there. The hot wire to your light let’s that electricity get to the light. The neutral goes, eventually, to the ground. The electricity goes from the power lines, down the hot wire to your light, through it (powering it) and down the neutral to the ground. Electricity can’t flow if it doesn’t have somewhere to go. Comes in on the hot, goes out on the neutral.
Electricity comes in what’s called phases, in Europe usually three in America typically two fro residential houses. For simplicity let’s stick to the American system with two: these two phases are exact opposites, so they always have the same value but if one is positive the other is negative and because voltage adds up, if you connect the correct two cables of the two phases the resulting voltage is zero because they always cancel each other out. -> 1+ (-1)=0
Now why it used like that: let’s stick with the two phases like before. You would think to close the circuit on these two phases you would need four cables to the power station, and because the carry power they need to be big cables to keep the resistance low. But when you connect the two phases like I said above you suddenly only need three cables and only two of them need to be big because the neutral wire doesn’t carry any electricity because it’s voltage is always 0. So if we look the the power grid you can use less cables, which saves a lot of money.
Essentially you still need the neutral to actually close the circuit of the different phases but since it’s voltage is zero because of how it is connected it doesn’t carry any electrocity
ELI5: electric phases cancel each other out, hence the neutral wire with zero voltage, but you still need it to close the circuit because all electric circuits must be closed to work.Therefore Money is saved, plus other benefits of doing it like this.
ELI5: The Neutral returns the electricty back to the generation point in a single-phase system, completing the circuit and allowing it to do work.
ELI10: As others have mentioned, in North America most homes are fed by what’s called a split-phase transformer, meaning that it takes one phase of the transmission grid onto the “primary” coil (Usually operating at or above 5000 V, notated as 5kVA) and lowers the voltage to 240 Volts AC on either end of the “secondary” coil. A connection terminal is then placed into the center of the secondary winding and provides the Neutral for all of your ‘single phase’ devices downstream. When you measure for VAC between this center point and one of the end points on that secondary coil, you get 120VAC, amd when you measure between the two end points you get 240VAC and the Alternating Current changes the polarity of those lines, allowing each line to serve as a Neutral interchangeably when used together for something like a stove or AC unit. This switching between hot and neutral happens roughly 60 times a second in North American systems, and 50 (I think, Europe is weird to my Yankee arse) times a second in Europe.
A neutral wire is just basically a reference point. There is potential energy in one side of the line but if there is no connection, like through a light bulb, the energy has no path to flow through. A neutral provides that path to ground. A neutral line can be called a ground and not in certain situations and the application, but that’s another conversation.
It’s why, and don’t try at home, you can hold the hot leg of a power outlet if you’re insulated from the floor properly and be completely fine. There is no path to ground for the electricity to flow.
Now this is mostly for home voltages. There are Distribution line systems that can have setups without neutrals. They’re considered Delta configurations and only have 3 hot wires, but the most common you’ll see is Wye configuration with 3 hot and a neutral. Delta uses the Phase to Phase measurement to determine voltages.
Electricity needs to go in a loop to complete a circuit. So if you’ve got a wire bringing you fresh electricity from the power plant, you need a second wire that brings your used electricity back to the powerplant when you’re done with it.
It’s a similar idea to the shower in your house – you have a faucet that fresh water comes out of, and a drain/sewer system for dirty water to go back to the water treatment plant. If you take 10 gallons from the faucet, 10 gallons go down the drain. Similary, if you pull 10 amps of current from the hot wire, there’s 10 amps of current going back down the neutral wire.
However, because there’s no pressure behind it, you won’t necessarily get shocked if you touch the neutral. The same way that if you have a burst pipe to your faucet, it sprays out water constantly, but if you have a leaky drain pipe it only drips when you’re taking a shower.
Also, to extend it a bit, a ground wire is a bit like having a second drain hole in your floor. If your primary drain gets clogged and the water won’t shut off, the floor drain will collect the overflow. That’s why there’s a lot of amateur bullshit with mixing neutrals and ground – you need both wires for safety (with specific rules on how they are tied together) but electricity works fine with just one of them.
Not an electrician. I’m curious if anyone would expand on this and explain why hot-neutral-ground is a preferable system to hot-hot-ground, assuming the same end voltage in both cases. The latter to ground would be half the voltage of the former no? Is it to simplify the panel? Is it solely so high voltage appliances can be serviced as two phase?
To use the plumbing analogy, the neutral wire is your drain, where the electricity flows out of your device (and then out of the house) to the sewer (for electricity it’s the power station). The hot is like the faucet, which is pumping the electricity into your device. Your device is like the sink basin. Ground is not as well represented by the analogy but the purpose of it is kind of like the overflow drain opening in the sink if it was actually a completely different drainpipe, and it prevents the sink from overflowing and then filling the room past your head, thus protecting you from drowning.
Man there’s some weird answers here. The neutral wire is named neutral because it’s kept at the same potential as the ground. Meaning if you touch it, you won’t get electrocuted normally. But you still need 2 wires to complete the circuit wether you are using AC or DC. You need a loop. Without a neutral wire you wouldn’t have a complete circuit . But it doesn’t have to be neutral to do that. In fact in direct current circuits there is no neutral
The neutral wire takes the electricity home. The Earth cable is a fire exit for electricity in an emergency
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