A C wire or Common wire transformer is use to power Nest Thermostats that are showing low power or low power errors. In most cases the addition of C wire transformer can fix the power error on the Nest Thermostat.

Is the common wire live or neutral?

White. The common is the neutral or ground wire, depending on the type of circuit. In normal US residential wiring, youll have a black hot wire, a white neutral or common wire, and a green or bare ground wire.

Which wire is neutral on a transformer?

Commonly the system neutral is connected to the star point on the feeding transformer. This is the reason that the secondary side of most three-phase distribution transformers is wye- or star-wound. Three-phase transformers and their associated neutrals are usually found in industrial distribution environments.

What is the white wire on a transformer?

The black wire is hot, the white wire is neutral, and the green is earth ground. Connect the transformers two red wires to the neutral wire, and the two black wires to the side tab on the fuseholder, and your hot lead to the bottom terminal of the fuseholder. Adding a power switch is a good idea.

What does the common wire mean?

The common wire is normally the white wire, at least in the United States, and is often called the neutral wire. Its also called common because all circuits in the house typically have the white wires tied together, which means every circuit has that wire in common.

Why is the neutral of a transformer grounded?

Neutral earthing resistors are used to limit the fault current in transformers When a phase to earth occurs, the fault current is limited only by the soil resistance. This current, which can be very high, can damage the windings.

Is a white wire positive or negative?

The black wire is positive, the white wire is negative, and the green wire is the ground.

Why neutral is grounded in transformers?

Neutral earthing resistors are used to limit the fault current in transformers When a phase to earth occurs, the fault current is limited only by the soil resistance. This current, which can be very high, can damage the windings.

What is the common wire used for?

The wire that carries electricity from the bulb back to the source is the neutral wire, or common wire.