How to connect the neutral wire light switch correctly

In general, the food chain is like a giant loop. Electricity constantly flows around it to create the necessary capacities for various equipment. Any breaks in this circuit immediately lead to a complete cessation of power supply. The neutral wire helps to securely close it and return the current back to its source, keeping household appliances working.

Its main purpose is to ensure the direction of electricity to the starting point. It is accompanied by two more live cables and one grounded one.

Two hot ones conduct energy from the battery to the lamp. The neutral then carries the current back to its source and completes the circuit.

The earth is only for safety. With an abnormal flow or surge of electricity, a charge will be sent into it.

Hot wire

Such a cable is designed to carry power from the load back to the source, and “hot” cords transmit current in the opposite direction.

Anything that requires electricity is considered a load. Its scope includes any lamp, toaster, iron or hair dryer.

In the USA, “split current 240 V” is used. Each of the hot wires provides 120 V, and both together provide 240. When the load on them is unbalanced, which happens most often, the neutral wire carries the excess in the opposite direction.

Hot wire

Let’s say that 12.5 amperes of electricity flows through the “hot” cable, and 15 amperes through the other. Then the neutral cord will transfer 2.5 (15–12.5) to the power source. This circuit completes the circuit.

If only one of the hot ones is providing 15 amps, the neutral will send that much back and complete the process.

If the same current flows through both hot ones, the neutral one does not transfer electricity to the other side. Then the circuit will be closed due to the movement of current between them.

Therefore, hot wires transfer energy from the power source to any technique, and neutral ones return it back (if the current between them is not balanced).


Grounding cables provide alternative paths for power to travel in the event of an interruption in the hot and neutral cords it would normally be routed through. This path takes electricity deep underground beyond the boundaries of human habitation.

“Ground” wires under normal conditions do not let it through. They are used only when anomalous flows are shorted to the ground.

If lightning strikes the house, then there is a transition of the impulse to the ground. Then the corresponding cable will receive electricity from the elements and redirect it to the ground. Such actions will also cause the switch on the panel to operate, cutting off all power in the house.


Presence of neutral wires

The easiest way to determine the presence of a neutral cable in a lighting junction box is to inspect it. But it is worth considering a few important recommendations.

  1. Homes built before the 1980s most often have neutral cords.
  2. If there is an outlet near the switch, then it is also equipped with an appropriate wire.
  3. Neighboring light relays are likely to be equipped with a neutral cable anyway.


In the United States of America, electrical codes are required to be colored in a certain color. These settings make the job much easier and make identifying different types of cords very easy.

Having done everything possible, you need to return to the switch and try to put it into action. If it does not light up, you need to continue troubleshooting.

Unscrew the front cover and remove it. Then you need to separate the switch. It is carefully pulled out of the wall without separating it from the wires. The purpose of each must be clearly defined.

  1. Hot cables are always painted white, red or black.
  2. Neutral cords are available in white or gray and are usually attached to a nut rather than a switch.
  3. Ground wires are bare, they are green or copper in color.

Following this scheme, each user is able to determine the presence of a neutral wire. In addition, there must be a white or gray coil not connected to it behind the relay. If not, then most likely there are three cables: white, copper and black. There is no neutral cord and the owner of the home should not be confused by the fact that there is a white wire.

After determining their purpose, you need to take masking tape and mark each cable by removing it from the switch. You can even take a photo with your smartphone so that you can quickly locate it later. In any case, such a step will be useful. Otherwise, you will have to resort to the services of a specialist, because only he will be able to connect the necessary device.

Coloring wiring

Purpose of the neutral wire

Some circuits are not able to work without a zero cable, while others do without it.

For example, an ordinary switch in the house does not need electricity, but only leads it to a light bulb.

If a Smart Home system is installed, then a neutral cord is required. In this case, an uninterruptible power supply is required. Neutral helps complete the circuit and activate the switch. This process is carried out even when it is in a non-working position.

Most modern smart relays require a neutral wire to function, but there are some that don’t. However, they need a separate hub, for the purchase of which they will have to allocate a tangible amount.

No neutral wire

Laying a neutral cable

Some homeowners prefer to call an electrician and have him run neutral throughout the home. But it is unlikely that too many people will want to do this. Such actions are very complex, expensive and difficult to plan in advance.

Smart switch without neutral wire

The purchase of this device is a simple way out. There are several types, but the LutronCasetaSmartHome dimmer version is the best. There are many excellent reviews about it on the network and it is easy to set up on your own.

To ensure the operation of smart switches, you will also have to purchase an appropriate hub. If you have LutronCaseta dimmer equipment, you also need to buy a wireless smart bridge.

Using smart bulbs

Using smart bulbs

You can use smart bulbs and not know the difficulties with the corresponding light switches. But such devices also have disadvantages. The biggest one is that they refuse to work unless the relay is activated. Therefore, it should always remain in working position.

Such a difficulty can complicate a person’s life, so it is better to know about it in advance. Smart home appliances should make life easier for people, not complicate it.

Neutral wire voltage

It has already been said before that the main purpose of the neutral cable is to provide a path for the current to return back to the original source. And if there is a smart switch, it also adjusts the power supply, so it will always be on.

When there is voltage on the wire, it works. But you should be aware that this indicates the constant presence of nutrition. Therefore, it is required to approach the switchboard and deactivate the breaker.

But if the neutral is still energized, then it is worth calling an electrician. Only then can you continue to modernize the house. In this case, it is better not to try to cope on your own, but to invite a professional.

Connecting the neutral wire to the earth

Connecting the neutral wire to the earth

Many smart homeowners will want to ask the pertinent question of whether they can run a neutral cable to the ground. There are a huge number of similar queries in search engines. It must be said right away that it will not be possible to do such a thing. Ground and neutral cords cannot be used instead of each other. If you try to use them for other purposes, you can face very serious and dangerous consequences.

As mentioned before, the ground wire is completely unsuitable for transmitting electricity under normal conditions. It is used only as a precaution in the presence of an abnormal charge. By removing the ground or otherwise trying to interfere with a strictly defined circuit, you can get a very strong electric shock.