Electrical wiring, meaning of the term "hots"

On this site I have often seen the term "hots" used. With regards to electrical wiring, what does this term refer to? I am aware there is usually a positive, negative, and perhaps (not always) ground wire in home electrical cabling. Not sure what "hots" refers to.

While it's not a perfect analogy, think of this in terms of a kitchen sink (yes, I am throwing a kitchen sink at the question).

• The faucet - It's hooked to a pipe that brings water in so you can use it
• The drain - A pipe hooked to something that takes water away.

You then interface with the water within the sink.

In your circuit (because electricity requires one to work), you have the same basic thing.

• Hot wire - Typically black, this carries current in from your power company. This is your "faucet"
• Neutral wire - Carries electricity away to some sort of electrical sink (in most cases, the ground on the main service box). This is your "drain"
• Ground - Think of this as a wet/dry vacuum for when your kids play in the kitchen sink and spill water everywhere. Ground soaks up everything that should have gone down the drain but didn't. Since you dump your wet/dry vac down the drain when you're done, it all goes to the same place eventually.

Why do we call it "hot"? Because it burns (sometimes literally) if you touch it while it's energized. It also might lead to dancing, colorful metaphors and other bad things

AC isn't so polar

DC has a clearly defined polarity to it -- one end of a battery is positive and the other is negative. However, an AC source goes from being all the way positive to all the way negative and back again. This means that we don't have "positive" or "negative" in AC circuits. In an isolated circuit, in fact, the two supply leads are equivalent and interchangeable.

However, in order to make an isolated circuit safe, you need a reliable way to detect that electricity is flowing where it shouldn't be, and we didn't get that until the introduction of reliable, miniaturized ground-fault protection devices in the 1960s. Another means of detecting "hard" ground faults was needed, and way back when, it was decided to do this by connecting one point on the AC supply to ground -- this becomes the neutral, or grounded conductor if you're reading the NEC. As a result, a fault from the grounded conductor to the grounding system flows back through the grounding system to the neutral/ground bond in the main panel, and from there back to the source, so the resulting fault current blows the fuse/trips the breaker, or at least that's how the theory goes. (Grounding the system also keeps it from floating off to a high voltage relative to earth due to induced charges, but that's mainly a problem from a dielectric breakdown standpoint.)

Neutral is not Ground

Neutral is the normal (designated) return path for current heading back to the power source from the load. Ground is a "safety shield" or "drain" for wayward current. These are kept separate as ground is intended to be touchable and often is (at boxes or in metal conduits, for instance), so it can't have significant voltage on it or current flowing through it normally.

• By isolated circuit do you mean isolated AC circuit? Oct 12, 2017 at 8:53
• What about the difference between ground and neutral? Could you please include a diagram of your explanation? Oct 12, 2017 at 8:58
• For example: en.wikipedia.org/wiki/Ground_and_neutral Oct 12, 2017 at 13:19