CEC Rule 10-114
Grounding Conductor Size
The grounding conductor is your system's critical link to the earth. If lightning strikes or a high-voltage cross occurs, this wire safely dissipates the energy. Because it must handle massive transient events, its size is directly tied to the size of the largest service conductor or equivalent ampacity of the service. In Canada, you look up the ampacity of your service conductors in Table 16 to find the minimum required size for the grounding conductor. For instance, a typical 200A residential service requires a #6 AWG bare copper grounding conductor. Note: The CEC restructured Section 10 heavily in recent editions, shifting terms from 'Grounding Conductor' to 'Grounding Electrode Conductor' to align closer with international norms, but the sizing mechanics remain rooted in Table 16.
When You Need This
- Wiring a new residential service and picking the bare copper wire to run to the ground rods or water pipe.
- Upgrading a service from 100A to 200A and verifying the existing ground wire meets code.
Key Points
Common Mistakes
Confusing the Grounding Conductor (Table 16 - to the dirt) with the Bonding Conductor (Table 16A/17 - to the equipment).
Running an oversized #3/0 AWG ground wire to a simple ground rod (it maxes out at #6 AWG under specific electrode exceptions).
Using aluminum wire directly into the soil.
Exam Tip
Table 16 is for Grounding. Table 16A/17 is for Bonding. The Red Seal will try to trick you by asking for the 'bonding' size but giving you the service entrance scenario. Read carefully!
Frequently Asked Questions
Yes, stranded copper is perfectly acceptable and often preferred for sizes #6 AWG and larger due to flexibility, provided it is properly terminated.
Inline Tools
Grounding Calculator
Size grounding electrode conductors per NEC 250
Related Code Sections
This is an educational summary, not the official code text. The NEC® is a registered trademark and copyright © National Fire Protection Association (NFPA). The CEC is copyright © CSA Group. For official code text, visit nfpa.org or csagroup.org. SparkShift is not affiliated with NFPA or CSA Group.