Do I need a permit to add a subpanel?
Usually needs a permit
A subpanel means a new feeder and new distribution, not a repair — that is permit work essentially everywhere, and the inspection exists to catch one specific mistake.
What changes the answer
- Any new subpanel — permit required; a feeder is new distribution, not maintenance
- In a detached garage, shop or barn — permit required, and that building needs its own grounding electrode
- Feeder run underground — the trench is usually its own hold point, inspected before you backfill
- Replacing an existing subpanel in place — still a permit in most jurisdictions
- Many jurisdictions will not issue electrical permits to a homeowner at all
These thresholds come from the model code and are commonly amended locally, which is usually where people get caught.
Why it matters
The mistake this inspection is looking for is neutrals and grounds bonded together in the subpanel. It works, everything turns on, and normal current now flows on the ground path and on any metal it touches — including the water pipes. Nothing about that is visible once the cover is back on.
Confirm the requirement with the authority that would issue the permit before deciding.
The version of this people actually ask
Do I need a permit to add a subpanel in my garage or shop?
Yes in nearly all jurisdictions. A subpanel is a feeder, an overcurrent device and a grounding arrangement, and the two things most often got wrong are invisible once the cover is on: neutrals and grounds have to be separated downstream of the service disconnect, and a detached building needs its own grounding electrode. Both are silent failures that only matter during a fault.
Do I need a permit to run power to a detached garage or shed?
Yes, and it is a bigger item than the panel itself. The feeder is usually buried, so burial depth, conductor type and sizing over the run length, and the disconnecting means at the building all come into scope. An otherwise permit-exempt shed does not make the wiring to it exempt.
Does my subpanel need a four-wire feeder?
A modern feeder to a subpanel carries two hots, a neutral and a separate equipment grounding conductor, with the neutral isolated from the enclosure at the subpanel. Three-wire feeders to detached buildings were allowed under older code editions and plenty exist, but that allowance was removed, and an existing installation being legal when built does not carry over to new work.
This is the typical rule, not your answer
This is the typical rule in the United States and not a decision about your property — permitting is run by more than 22,000 separate authorities and any of them can amend the code it adopts, so confirm with your local building department before you start. Put a ZIP in to see what applies in that state, and how to reach the office that decides.
Electrical permits are required under the adopted NEC / IRC Chapter 34; subpanels are not in the R105.2 exemption list. Neutrals and grounds must be separated downstream of the service disconnect — NEC Article 408 and 250.24(A)(5) — and a detached building fed by a feeder needs its own grounding electrode under NEC 250.32.
Add a subpanel state by state
Which building code a state adopts, and whether it binds the whole state or leaves it to each city, changes how far the rule above gets you. These pages carry that, plus the county building departments we have verified in each.
- Subpanel permits in Texas Mixed — state and local · 45 verified county offices
- Subpanel permits in Georgia Statewide adoption · 29 verified county offices
- Subpanel permits in Virginia Statewide adoption · 29 verified county offices
- Subpanel permits in North Carolina Statewide adoption · 26 verified county offices
- Subpanel permits in Illinois Home rule — local adoption · 23 verified county offices
- Subpanel permits in Michigan Statewide adoption · 22 verified county offices
Other projects
- Build a deckA permit is usually required once a deck is more than 200 square feet, more than 30 inches above grade, serves an exit door, or is attached to the house.
- Put up a fenceFences under 7 feet are typically exempt from a building permit — but height limits, corner-visibility rules and pool-barrier requirements are set locally and catch people constantly.
- Add a shed or small outbuildingOne-story detached sheds are typically exempt up to 200 square feet under the residential code — but the number people quote is 120, and both are right depending on which code your jurisdiction adopted.
- Replace a water heaterReplacing a water heater almost always requires a permit, even though it is routinely done without one.
- Remove or open up an interior wallIf the wall is load-bearing, a permit and engineered drawings are required. If you are not certain whether it is load-bearing, assume it is.
- Upgrade or replace an electrical panelPanel and service work always requires a permit, and in most places must be done by a licensed electrician.