What is an open neutral?

Question

What is an open neutral?

Answer 1

You have four answers already. I'm posting mine because three of them have incorrect facts. It is amazing to see so many incorrect answers from people who claim to be experts.

Simplistically, an open neutral means that the neutral wire is not connected. It might be the wiring from the street to the house or from the service entrance panel (breaker box or fuse box) to an outlet or device.

Usually that term is used to refer to the line into the house. Actually, the broken connection could be far away from the house, even a few hundred feet.

Some devices will work if the neutral line is not connected. For example, an electric water heater or parts of an electric oven. Other things, or parts of things will not work properly. Why is too technical to talk about here.

Actually, I have seen a completely broken neutral going into a house and there were no significant symptoms. Again, the reason why is beyond this discussion, but it can happen. More often, you will see some items work and some not. In this case, the only way to tell it was broken was to visually see it. Had I not seen it, there are tests to check for this problem.

You can also see some things work and some not if one of the two hot lines into the house is broken. Because of that, it is usually fairly easy to diagnose that problem.

It is totally incorrect to say there is little current flow from the neutral to the ground or visa versa. The correct statement is there is absolutely no voltage and no current flow unless there is a significant problem. The difference can be important in some discussions. The neutral is physically and electrically tied to the ground inside the breaker box AND outside the house.

It is also incorrect to say the "spent" current travels on the neutral. The EXACT same current flows through the hot and the neutral. To be technical, it first flows one direction then the other, switching about 120 times per second (for a 60Hz line). You don't need to know that though.

The ground wire is NOT there to protect the outlet. It is there to protect people, animals, etc from dangerous shocks. It is also partly there to protect your house, etc from fires or other damage from short circuits.

Answer 2

Modern electrical outlets have three wires.  One (usually black) is the hot lead, the white is the neutral and the bare copper or green one is the ground.  If installed correctly, the power flows from the service panel to the outlet through the black wire.  It powers whatever is pugged into the outlet and the spent current flows back to the service panel along the white wire.  The ground wire is only there to protect the outlet. If the hot or live wire touches anything it is not supposed to the ground makes sure that it shorts out and trips the breaker.  

If the white or neutral wire is not loose or broken or not installed correctly the outlet may still work because the ground can sometimes act as the neutral wire.  In such an instance, an outlet testor will signal that there is an open neutral.  An open circuit is a broken circuit.  

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Answer 3

As simple as I can make it:

Each circuit has two wires with voltage between them.

When a device is connected across these two wires, it runs.

On of these wires, (Phase, or Line), has voltage to ground,

and is protected by a circuit breaker.

The other wire, (Neutral or common), is maintained at

ground potential.

(Very little current will flow from neutral to ground.)



In case of an "Open Neutral "  where the neutral connection

is missing or somehow broken, a 'sneaky situation' exists

where a properly connected device won't work, (because

current needs the complete circuit to flow), but voltage to

ground, (the possibility of a dangerous shock), still exists.

There's a lot unsaid, ... but that's the basics.

That white, Neutral wire should be part of an unbroken

chain of wires back to the panel.  ...  It's not.

In most cases where a test finds an open Neutral, it is

eventually traced to a bad connection caused by using the

receptacle 'push-in' wire terminals as splices.

Answer 4

it is not attached to the circuit box--the main breaker box.

Answer 5

Somewhere (not necessarily the in the breaker box) the neutral wire is not connected or possibly broken.