Neutral wire guide

What Is a neutral wire?

A neutral wire is part of the electrical circuit in a home. Where current is brought to your switch and/or fixture on a hot or line wire, the neutral carries the current back to the source – completing the circuit.

A traditional mechanical switch simply interrupts the flow of current by making or breaking the circuit when you flip the switch with your finger. On the other hand, smart switches such as Nokia Smart Lighting switches always need power so they can be operated remotely or automatically by a schedule. For this reason, the circuit must be made at all times at the switch and therefore a neutral wire is needed within the switch box.

How to tell if I have a neutral wire?

All houses have a neutral wire, so the better question is, "Do I have neutrals in my switch boxes?" To answer this question, here are some guidelines:

  • If your house was built anywhere from the mid-1980s onward, there’s a strong chance you’ll have neutrals throughout your home.
  • If you have an outlet on the wall near the switch, the switch box almost certainly contains a neutral.
  • If they are ganged switches, then there's a much higher likelihood of having neutral wires.

If you’re still in any element of doubt, it’s time for further investigation…

Checking The Switch Box

Before you check in your switch box for neutrals, observe all sensible safety precautions before touching any electrical wiring or consult an electrician for assistance.

  • Turn off the circuit breaker that feeds your wall switch.

Note: if it is a multi-gang switch box, it can have multiple circuits feeding the different switches so test the other switches to ensure power to their fixtures has been turned off.

  • Remove the trim plate covering the switch.
  • Take out the screws from the switch.
  • Pull the existing switch away from the wall so you can examine the wires.
  • Look for two or more white wires that are tied together with a wire nut. These are likely neutral wires.

To make sure the wires are neutral, use a voltage detector between the white wire and the line/hot wire in the box. You should see 110-120V.

What to do if you don’t have a neutral wire in your switch box?

If you don’t have a neutral wire at the switch box, call an electrician and have them run a neutral wire from the fixture to the switch box. This should be straightforward and simple task.