How to Wire an Exterior 50-Amp Generator Inlet Box (2026)
Wiring a 50-amp power inlet box requires 6-AWG copper conductors, raintight exterior conduit, and a dedicated 50-amp double-pole breaker interlocked with the main service disconnect.
01 Essential Electrical Hookup Hardware
A power inlet box mounts on your home exterior, providing a safe male receptacle to receive generator power. Heavy 6-AWG pure copper THHN conductors route through conduit to your main electrical panel.
The Reliance PB50 inlet box features a raintight spring-loaded door and patent-pending thermal powder coat protection.
- Requires 4-wire installation: two hot legs, one neutral, and one equipment ground.
- Conductors must be sized at 6-AWG copper for continuous 50-amp service.
- Outdoor conduit must use weatherproof PVC or liquid-tight flexible metal.
02 Step-by-Step Installation Checklist
Always shut off your home 200A main service breaker and verify zero voltage with an insulated multimeter before loosening panel covers.
Install a mechanical interlock bracket that physically blocks the generator breaker from switching ON unless the main service breaker is switched OFF.
- 1 Mount Exterior Inlet Box: Fasten NEMA 3R inlet box at least two feet above grade line on exterior wall.
- 2 Pull 6-AWG Copper Feeders: Pull two black/red hots, one white neutral, and one green ground through conduit.
- 3 Install Panel Interlock: Secure UL-listed breaker interlock bracket directly over the 50A breaker position.
- Use 6-AWG copper wire for all 50-amp generator inlet runs.
- Mechanical interlock kits eliminate backfeeding utility lines.
- Torque all breaker terminals to factory inch-pound specifications.
Frequently Asked Questions
Q: Can I use 8-AWG wire for a 50-amp generator inlet?
No. Under NEC Table 310.16, 50-amp circuits require 6-AWG copper conductors to prevent conductor overheating under continuous storm loads.
Q: What is the difference between CS6375 and NEMA 14-50P inlets?
The CS6375 (SS2-50P) uses a locking twist collar to seal against wind and rain, while 14-50P uses straight blades.