Electrical 101

Open Neutral

Open Neutral Wiring

In an electrical system, ground and neutral are connected together in one location only, at the neutral point. This connection is either at the power company transformer or in or near the main electrical panel of the dwelling (see Electrical Circuits).

On a 120, 240V circuit, the voltage on a neutral wire is normally 0V (volts) on a live circuit. However, if a neutral wire is open, the voltage on the line side of this open neutral is 120V. Find Multimeters

Multi-Wire Branch Circuit Wiring Diagrams

Open Neutral Wiring Diagram

In the diagram above right, the neutral is opened. The neutral wire on the left side of the open (comes from the panel) is 0V. The wire on the right side of the open (goes to the load) and is 120V.

In the diagram above left, both circuit breakers and switches are closed.

In the diagram above right, neutral is open. The neutral wire on the left side of the open (comes from the panel) is 0V. The wire on the right side of the open (goes to the load) is 240V to ground. 120V A phase and 120V B phase combine for 240V to ground.

A and B phase circuit breakers are open

A and B phase circuit breakers are closed

Neutral is open

A phase circuit breaker is open

In the diagram above left, the A phase breaker or switch is open. The neutral wire on the left side of the open (comes from the panel) is 0V. The wire on the right side of the open (goes to the load) is 120V to ground.

In the diagram above right, both phase A and B breakers or switches are open. The neutral wire on the left side of the open (comes from the panel) is 0V. The wire on the right side of the open (goes to the load) is also 0V.

See Multi-Wire Branch Circuits and Open Neutral Multi-Wire Circuit for more information.