30A vs 50A — which inlet is right for you?

Match the inlet to your generator's highest-output twist-lock outlet. You'll know by looking at your generator's panel:

30-Amp Inlet NEMA L14-30P

For generators ≤ 7,500 watts running. The common size for portable generators in the 5–7kW range. Three-prong twist-lock, 240V split-phase. Inlet box is slightly smaller and cheaper to install.

What it powers: Fridge, lights, WiFi router, gas furnace blower, well pump (smaller), a few outlets. Not enough for electric water heater or central A/C.

50-Amp Inlet NEMA CS6375 / 14-50P

For generators ≥ 10,000 watts running. The common size for 10–12kW portables. Four-prong twist-lock, 240V split-phase with neutral. More copper, larger breaker.

What it powers: Everything the 30A does, plus well pumps with larger HP, electric water heater on reduced draw, central air on smaller 2-ton or smaller units, shop tools.

What if I have both outlets on my generator? Most 10–12kW portables offer a 30A twist-lock AND a 50A outlet. We'll install the 50A inlet if you plan to pull more than ~7kW during outages, otherwise the 30A keeps the install cheaper.

Where we mount the inlet box

Placement matters. The inlet box is code-required to be outside the dwelling, reachable by your generator cord, and protected from direct weather. We'll discuss location during the quote visit. Typical placements:

Exterior wall near panel (most common) — shortest conduit run, cheapest install. Usually back/side wall.
Garage exterior or attached carport — works if your panel is in the garage. Keeps the generator covered.
Deck or patio wall — if the panel is interior but you want a sheltered plug-in spot. Adds conduit run.
Freestanding post — possible but rare; adds cost for the post + underground conduit.

All inlet boxes we install are rated NEMA 3R (weatherproof) with a spring-loaded cover. No rain in the plug.

The install process

Quote — we visit, photograph the panel and proposed inlet location, match the right NEMA receptacle to your generator, and text a locked-in price.
Permit — pulled under SC License 2942 with your city or county. 1–7 days to approve depending on jurisdiction.
Install day — inlet box mounted (usually 3–5 hours), conduit run, generator breaker + interlock kit installed in the panel, labels applied per NEC 700.5 / 702.6.
Inspection — the jurisdiction inspector verifies the install. We stand for the inspection; you don't need to be home.
Walkthrough — we show you how to power the house safely: main off, generator started, interlock slid, generator breaker on, pick which circuits to run.

FAQ

Do I need a specific cord? Yes — one rated for your generator's output and long enough to reach the inlet. 25-ft is typical, 50-ft max. Cord cost is included in the $1,197 (if your generator doesn't come with one).

Can I upgrade from 30A to 50A later? Yes — the cost of re-doing an inlet is less than the install the first time ($300–$500) because the conduit + panel work is already done. Easier to size it right up front if you think you'll upgrade your generator.

Does the inlet work with any generator? Only generators with the matching twist-lock outlet (L14-30 for 30A inlets, 14-50 or CS6364 for 50A). If your generator is 120V-only, it's not compatible. Upgrade to a 240V portable, then book.

What about gas / diesel / dual-fuel? The inlet doesn't care what the generator burns. As long as the output outlet matches, any fuel works.

Generator Inlet Box Installation

30A vs 50A — which inlet is right for you?

30-Amp Inlet NEMA L14-30P

50-Amp Inlet NEMA CS6375 / 14-50P

Where we mount the inlet box

The install process

FAQ

Ready to plug it in the right way?