Generator Power Inlet Boxes

Generator power inlet boxes make generator hookups safer, faster, and cleaner. Mounted outside your home or business, an outdoor power inlet box lets you plug in a portable or standby generator with a single cord, then feed power to a transfer switch or interlock inside. That means no running extension cords through doors, no fumes indoors, and no risky backfeeding. A weatherproof, UL Listed inlet with a gasketed, hinged cover keeps connections protected during storms, while clear labeling and, on some models, power-on indicator lights add confidence during outages.

These boxes are built for tough conditions. Look for NEMA 3R rainproof enclosures in powder‑coated steel or corrosion‑resistant aluminum, with spacious wiring compartments, grounding lugs, and multiple knockouts for clean conduit runs. Common configurations include 30‑amp L14‑30 (120/240V) for mid-size generators and 50‑amp SS2‑50 for higher output units. Pair the inlet with the correct SOOW cord (e.g., 10/4 for 30A, 6/4 for 50A) and a code‑compliant transfer solution to safely energize selected circuits or your whole panel.

How to choose the right generator inlet box:
- Match amperage and plug type to your generator: 30A L14‑30 (up to ~7,500W) or 50A SS2‑50 (up to ~12,500W+).
- Confirm voltage: most residential systems use 120/240V split‑phase.
- Choose a NEMA 3R weatherproof enclosure for outdoor use; look for UL/cUL listings.
- Pick material and finish suited to your climate (coastal areas benefit from aluminum or stainless hardware).
- Check knockout sizes and entry orientation for simpler conduit routing near the service panel.
- Consider features like a flanged, angled inlet for strain relief and green “power available” indicator lights.

Installation should be performed by a licensed electrician. Use only with a transfer switch or listed interlock to prevent backfeed, and follow NEC 702 and local codes. Keep connections dry, inspect gaskets and terminals periodically, and store your generator cord indoors. With the right generator power inlet box, you’ll restore critical loads quickly and safely during an outage.