Have you ever wondered which electrical wire is the neutral one? You’re not alone. Even experienced electricians can get a little tripped up by this. Today, we’re diving into the topic to clear things up once and for all.
Identifying the Neutral Wire
Looking at your electrical panel, your eyes will likely be drawn to the neutral bus—the bar where all the white wires connect. It’s easy to assume that every white wire is a neutral, but that’s not always the case.
Technically, not all white wires are neutrals. Surprising, right?
The definition of a neutral wire is:
A conductor that carries the unbalanced load in a circuit.
In a typical AC circuit, the neutral wire completes the circuit by returning current to the source. It balances out the current flowing through the hot wires.
Neutral vs. Identified Conductor
Here’s where it gets tricky.
In your standard house wiring, you’ll often find a black, white, and a bare copper or green ground wire. Although we casually refer to the white wire as the “neutral,” technically, it’s called the identified conductor.
In Canada, code requires that this wire be white or gray. While it functions similarly to a neutral, it’s only truly a neutral when it’s part of a system with three or more wires where there’s potential for an unbalanced load.
A Practical Example
Let’s say you have 20 amps on the black wire and 10 amps on the red wire. The neutral (white) wire would carry the difference—in this case, 10 amps—back to the panel. That’s what we mean by “unbalanced load.”
But with a two-wire circuit (just a black and a white), there’s no way to measure that kind of difference. The white wire just completes the circuit, so it’s not technically a neutral—yet we still call it that on job sites.
Code Changes and the End of 14/3 for Branch Circuits
Recent changes to the electrical code in Canada now prohibit using 14/3 or 12/3 for most branch circuit wiring. Why?
Because arc fault protection is now required on most circuits that feed outlets, and multi-wire branch circuits (those using 3-wire cables like black/red/white) don’t support double-pole arc fault breakers.
This means electricians can no longer run one 14/3 cable to save time and materials by picking up outlets on one leg and lights on the other. Now, we have to run two separate 14/2 cables, which unfortunately increases labor and material costs.
Larger Circuits and Subpanels
In larger feeds—say a 100-amp subpanel—you’ll see a true neutral conductor as part of a four-wire setup:
- Black (hot)
- Red (hot)
- White (neutral)
- Bare or green (ground)
In these cases, the white conductor is a legitimate neutral because it’s carrying the unbalanced load from two hot wires.
Why It’s So Confusing
In many panels, especially newer residential ones, you might not see any true neutral wires at all. Every circuit could be a standard 120V (black and white) or a dedicated 240V (black and red), with no need for a neutral.
That’s why terminology gets messy. We refer to the white wire as a neutral even when it’s not functioning in that role.
The Old Way: Countertop Circuits and Multi-Wire Branches
Back in the ’90s and early 2000s, electricians often wired kitchen counter plugs using three-wire cable. For example:
- Plug 1: black and white
- Plug 2: red and white
In this setup, the white wire was a true neutral, carrying only the difference in current between the two hots. But that’s no longer allowed under current code, and now each outlet must be fed by a dedicated 120V, 20-amp circuit.
Final Thoughts
Hopefully, that cleared things up—at least a bit! Neutrals can be confusing, especially with code changes and evolving terminology. But here’s the key takeaway:
A neutral wire is one that carries the unbalanced load between two or more hot wires in a circuit.
In standard residential wiring, what we often call a “neutral” may actually just be an identified conductor. It completes the circuit, but it doesn’t always carry an unbalanced load.
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