Lessons · Electrical · the neutral is not a ground
The neutral carries current; the ground carries none, until the day it matters
The neutral is the return path for every 120 V load and carries current all the time; the equipment ground is bonded to the same bar at the service but carries current only during a fault. They are tied together at exactly one point and nowhere else, so a fault has a clear path and the ground wires never share the load's current.
Hone is a place to practise a career, one idea a day. This is one of its lessons, written out in full and free to read without an account.
What it is for
A subpanel where someone landed the neutrals and grounds on the same bar: now the neutral's current splits between the white wire and the bare wire, every metal box in the building carries a share, and a lost neutral puts 120 V on every one of them. The rule that they meet once, at the service, is not paperwork.
How to think about it
At the main service: neutrals and grounds on one bonded bar, or two bars with a bonding jumper. Everywhere downstream, subpanels included: neutral bar isolated from the can, ground bar bonded to it, no jumper. Never open a neutral under load: de-energize and verify it dead first, because an open neutral on a shared circuit puts 240 V across a 120 V appliance.
Worked example
Main panel: neutral bar bonded to the enclosure, grounds on the same barThe one place. This is the bonding jumper.
Subpanel: neutral bar on insulators, grounds on a separate bar screwed to the canNo jumper. The neutral current has one path home: the white feeder wire.
Shared neutral opens: a 12 Ω load and a 36 Ω load now sit in series across 240 VThe classic multiwire-branch-circuit failure.
I = 240 / (12 + 36) = 5 A; the 36 Ω load sees 5 × 36 = 180 VA 120 V appliance at 180 V. This is how a lost neutral destroys electronics through a whole house.
Your turn
A subpanel. Write whether the neutral bar is bonded to the enclosure.
subpanel neutral bar: from the can
Solve one, graded on the server
The trap
Seeing zero volts from neutral to ground and concluding the neutral is fine. Under no load they read the same because they meet at the service. Put a load on and measure again: a bad neutral shows volts between the two, and that is the reading that finds it.