Code Applied by the app elec.ground.electrode-conductor
Grounding electrode conductor size
The conductor from the service to the water pipe and the ground rods is sized from the service conductors, and #3/0 copper service conductors want a #4 copper grounding electrode conductor.
| When | The app uses |
|---|---|
| copper service conductors #2/0 or #3/0, copper electrode conductor | #4 AWG |
- Source
- NEC · 250.66, Table 250.66 · read the public text
- Editions checked
- 2017 · 2020 · 2023
- Used by
- Courses
- Amendments
No state or local amendment to this rule is on file. Not on file means the model code as written — check your jurisdiction.
A model code the authority having jurisdiction adopts.
The grounding electrode conductor ties the service to the earth: to the metal water pipe, the ground rods, the building steel. Its size comes from the largest service conductor, so the course's service, #3/0 copper, gets a #4 copper grounding electrode conductor.
On a bid it is a short run of heavy bare or green wire, clamps and rods that the one-line draws and the floor plan does not, easy to leave off.
What the app does with it
The electrical course teaches it on a card (Chapter 7, Read the one-line), and check-lesson-rules holds the card's numbers to this rule. The app counts it only if you draw it and write its conductor.
Verify against your edition
Table 250.66 gives #4 copper for #2/0 or #3/0 copper service conductors. The part that is the only connection to rod, pipe or plate electrodes never has to be larger than #6 copper (250.66(A)), and a concrete-encased electrode's never larger than #4 (250.66(B)). The #4 is the table's figure for the water pipe connection. Local amendments still govern.
Settled 2026-09-27 by Claude on the owner's delegation, from the dossier's research and the model code text; not checked against a printed book or a local amendment.
Cited by section, not reprinted: the code text belongs to its publisher. Company practice is not a rule here — it lives with your pricing.