Equipment grounding conductor sizing wrapper
Why you care (60 seconds)
EGC sizing is a safety-critical check. An undersized EGC can delay fault clearing and trigger inspection failures.
Where people lose time
- Using conductor ampacity tables instead of EGC sizing rules.
- Forgetting to upsize EGCs when ungrounded conductors are upsized.
- Treating EGC sizing as optional on short runs.
This is
The rule in plain language
Size equipment grounding conductors based on the OCPD rating, with adjustments when ungrounded conductors are upsized.
When it applies
Any time you install or verify equipment grounding conductors for feeders or branch circuits.
What you must do (checklist)
- Identify the OCPD rating protecting the circuit.
- Select the EGC size using the EGC sizing table.
- Upsize the EGC when ungrounded conductors are upsized.
- Confirm terminations and bonding are continuous.
Quick examples
- Upsizing feeder conductors may require a larger EGC.
- EGC sizing is tied to the breaker or fuse rating, not load.
This is not
Common misreads
- Using neutral sizing rules for EGCs.
- Ignoring upsizing requirements when voltage drop adjustments are made.
What it doesn't cover
- Grounding electrode conductor sizing.
- Detailed bonding jumper sizing for services.
False friends
- A large raceway does not justify a smaller EGC.
Exceptions & edge cases
- Parallel conductors can change EGC sizing requirements.
- Certain equipment listings may add constraints.
Cross-references (NEC map)
- Primary: 250.122
- Secondary: 250.4(A)(5)
Exam traps
- Selecting EGC size from ampacity tables instead of the EGC table.
- Forgetting to increase EGC size when phase conductors are upsized.
Field notes
- Document EGC sizing in the feeder schedule.
- Check EGC size at pull points and terminations.
AHJ / Local amendments notes (placeholder)
- Add local amendments or interpretations here.
Revision notes
- Draft wrapper created for EGC sizing fundamentals.