Do I Need a Permit for Shed Electrical Wiring?
Yes — running electrical to a shed needs an electrical permit everywhere: the underground feeder, the shed's panel and circuits, and the grounding all require inspection. The shed's building-permit exemption (under 120 sq ft) does not extend to electrical work. Trenching the feeder without a permit risks striking utilities and creates uninspected wiring.
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What the permit covers
The underground feeder (burial depths per NEC Table 300.5 — 24 inches for direct-burial cable, 18 inches for PVC conduit, 6 inches for rigid under concrete), the shed's disconnecting means and panel (the subpanel with its grounding — the shed needs its own grounding electrode system), GFCI protection (all shed receptacles), and the branch circuits (lighting, receptacles per the planned loads). The inspection covers the trench (before backfill), the rough wiring, and the final.
Sizing the feeder
Load calculation first (what the shed powers — lights and outlets vs. workshop tools vs. EV charging — each a different feeder size): 20-amp multiwire for basic sheds, 30-60 amp feeders for workshops, larger for heavy equipment. Voltage drop (long runs to backyard sheds — size the conductors for the distance, not just the load). The house's panel must have the capacity (the load calculation includes the new feeder).
Common mistakes
Extension cords as permanent wiring (the classic violation — cords are not a wiring method), shallow burial (the unmarked shallow cable gets cut by the next digging project), no grounding electrode at the shed (the subpanel's ground rod — required for detached structures), and overloading the feeder (the workshop's table saw plus dust collector plus heater exceeds the 20-amp circuit). Cost: $1,500-$5,000+ for a permitted shed feeder installation.
The bottom line
Permit shed electrical — underground feeder at NEC burial depths, subpanel with grounding electrode, GFCI receptacles. Size for the loads and the distance; never use extension cords as wiring.
Torch Engineering PLLC · (480) 490-0064 · info@torchengineering.com — PE stamping backed by Apex Grid Engineering.