Why Are Neutrals And Grounds Separated In A Sub Panel(Canadian Electrical Code)
Today, we’re going to talk about neutrals and bonds in main panels and sub-panels—specifically how they should be wired according to Canadian Electrical Code.
What’s the Difference Between a Neutral and a Bond?
- Neutral: The return path for electrical current, usually a white insulated wire.
- Bond (Ground): The bare copper wire or green-insulated wire that connects all metal enclosures and devices to earth ground for safety.
Canadian Code Requirements: Keep Them Separated
Here in Canada, the rules differ a bit from the U.S.
- In the U.S., it’s common to see neutrals and grounds bonded together in every panel.
- In Canada, neutrals and bonds must be completely isolated from each other in all sub-panels.
The only place where the neutral and bond (ground) can be connected together is in the main service panel—the first point of disconnection.
Main Panel Setup
In the main panel, you’ll find a bonding screw or a bonding strap that connects the neutral bar to the grounding system (usually ground rods or plates outside).
This is the single bonding point allowed. From this point forward:
- Neutrals must be isolated on a neutral bus bar.
- Grounds (bonds) must be isolated on a separate ground bar.
Sub-Panel Setup
When running a sub-panel, you must not connect the neutral and ground again. Instead:
- Neutrals go to the neutral bar, which must be isolated from the panel chassis.
- Grounds go to the ground bar, which can be bonded to the sub-panel chassis.
If you tie neutrals and grounds together in a sub-panel, you create what’s known as a grounded neutral, which can lead to:
- Unwanted current on the ground wire
- Shock hazards
- Code violations
Testing and Inspection
To ensure everything is wired correctly, a megger test is performed during final inspection. This checks for any unintended continuity between the neutral and ground beyond the main panel.
If any grounded neutrals are detected in the system, they must be corrected before passing inspection.
Quick Recap
- ✅ Bonding is allowed only at the main panel (main service disconnect).
- ❌ No bonding in sub-panels—neutrals and grounds must remain separate.
- ⚠️ Improper bonding in sub-panels can cause serious electrical issues.
Final Thoughts
Always follow local code when wiring your panels. While practices may vary by region, Canadian code strictly enforces isolated grounds and neutrals in sub-panels. This helps ensure both electrical safety and code compliance.
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