What "generator inlet installation" actually means
If you own a portable generator, you have two safe and legal ways to connect it to your home: a transfer switch or an inlet box plus a panel interlock. Both stop your generator from feeding electricity back into the utility lines. What you cannot legally or safely do is run an extension cord into a dryer outlet or "suicide cord" the generator into the panel. That back-feeds the grid and can kill a line worker repairing your street.
A generator inlet installation is two pieces working together:
- The inlet box. A weatherproof outlet mounted on your exterior wall. Your generator's cord plugs into it. From there, the power runs through conduit into your breaker panel.
- The interlock. A small metal plate inside your panel that slides between the main breaker and a dedicated generator breaker. When the main is on, the generator breaker is physically blocked. When the grid is down and the main is off, you can slide the generator breaker on. It is mechanically impossible to have both on at once. That is exactly what makes it code-compliant, and exactly what the inspector checks.
Inlet + interlock vs transfer switch vs standby generator
All three are real options. Here is the honest comparison so you can see where the inlet + interlock fits.
| Inlet + interlock | Manual transfer switch | Standby generator | |
|---|---|---|---|
| Typical installed cost | $1,197 to $1,497 (you own the generator) | $1,800 to $2,600 | $12,000 to $20,000 |
| What it powers | Any circuit on your panel, the ones you choose | A fixed set of pre-wired circuits | Every circuit, automatically |
| Power source | Your existing portable generator | Your existing portable generator | A permanent unit on natural gas or propane |
| Starts automatically? | No, you start the generator and flip the interlock | No, manual | Yes, automatic |
| Best for | You own a portable and are home during storms | You want a fixed, labeled circuit set | Frequent multi-day outages, often away, medical loads |
For most Upstate SC homeowners who already own a portable generator and just want their essentials to stay on, the inlet + interlock is the lowest-cost compliant path, and it is what we install. If a standby unit is genuinely the better fit for your situation, we will tell you that honestly. More on how the hookup methods compare.
Which circuits can a portable generator actually run?
This is the question sizing guides skip. Your generator's wattage decides how much you can run at once. You add up the running watts of the circuits you want, plus the biggest starting surge (usually the well pump or AC compressor). A rough Upstate SC picture:
- Refrigerator / freezer: ~600 to 800 running watts (higher surge on start).
- Furnace blower (gas heat): ~600 to 1,200 watts. This is what keeps the heat on in a winter outage.
- Well pump (1/2 to 1 HP): ~1,000 to 2,000 running watts, with a large starting surge.
- Lights + outlets + internet: a few hundred watts total.
A common 7,500-watt portable comfortably covers fridge, furnace blower, well pump, lights, and internet, not all surging at the same instant, which is why you bring loads on one at a time. Running central air conditioning off a portable is usually not realistic, and we will not pretend otherwise. See our generator buyer's guide and sizing help.
One-day install, permit, and county inspection
- Quote. Text us your address. We confirm you are in Greenville, Spartanburg, or Pickens County, look at your panel and generator outlet, and lock your exact price before any work begins.
- Permit. We pull the electrical permit under SC License 2942. You sign nothing and handle no paperwork. Issuance time varies by jurisdiction, from a few business days to a few weeks in the busier county offices, we file the same day we quote.
- Install day. One visit, usually three to five hours: inlet box mounted and weatherproofed, conduit run to the panel, the generator breaker and interlock installed, everything labeled to code.
- Inspection. The city or county inspector signs off. You do not need to be home. We stand for the inspection.
- Walkthrough. We show you exactly how to power up safely and leave a written card on your panel.
What the $1,197 to $1,497 includes
- Weatherproof inlet box (30A or 50A)
- Interlock kit for your panel
- Generator breaker installed
- All wiring, conduit, weatherproofing
- The permit and permit fee
- The county or city inspection
- One-day labor, no return trips
- Walkthrough + power-up card
Almost no one in this category publishes a real number. We do, because the install is the same scope every time.
Common questions
Do I need a permit? Yes, and in SC only a licensed electrical contractor can pull it. We handle it and the inspection, both are included.
Can I install the interlock myself? The kit is sold at hardware stores, but panel work in SC requires a licensed electrician to permit and pass inspection. A failed DIY inspection costs more to fix than doing it right once.
Is back-feeding through a dryer outlet really that dangerous? Yes. It is illegal, it bypasses your panel's protection, and it can electrocute a line worker. The whole point of the inlet + interlock is to make that impossible. How the interlock prevents back-feed.
What if my panel is a Federal Pacific, Zinsco, or Pushmatic? We do not install interlocks on those, they have known safety issues. We will flag it on the quote and recommend a panel replacement first.