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Do you need a ground rod at a detached garage?
A detached garage with its own panel needs its own grounding electrode. Here's why, and the one common case where you can skip it.
The breakdown, in plain English
- A separate building fed by a feeder needs a grounding electrode system at that building, like ground rods.
- The exception: if the building is fed by just one branch circuit (a multiwire circuit counts as one) with a ground wire, you don't need the electrode.
- Run four wires to the garage panel: two hots, a neutral and a ground.
- In the garage panel, keep neutrals and grounds separate. No bonding screw.
- A single rod usually needs a second one at least 6 feet away, unless you prove 25 ohms or less.
- Why: the electrode helps with lightning and surges at that building. The ground wire back to the house is what clears faults.
Codes to look up
A building supplied by a feeder or branch circuit needs a grounding electrode, except when it's fed by a single branch circuit with a ground.
Run an equipment grounding conductor with the feeder and don't bond the neutral to ground at the separate building.
A single rod needs a supplemental electrode unless it has 25 ohms or less to earth.
These are plain-English summaries, not the code's exact wording. Always check the full section in the NEC edition your area has adopted, plus local amendments.
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