The honest answer, up front
Connecting a portable generator to your home the right way, through a weatherproof inlet box and a panel interlock, costs a flat $1,197 to $1,497 all-in with Backup Power Pro in Upstate SC. That is the total you pay, not a starting price and not a deposit. Almost no one in this category publishes a real number, which is exactly why we do.
What that price 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
National cost articles break this same job into parts, an interlock kit around $50 to $150, an inlet box $50 to $80, a back-fed breaker, wire and conduit, then labor, then a separate permit fee. We roll all of it into one number so nothing shows up as an extra after the fact.
Why online quotes range from $350 to over $1,400
The spread is real, and it is mostly about what each quote leaves out:
- Labor-only or travel-only quotes. A $350 number is often just the visit, with parts, permit, and inspection billed on top.
- Materials-only estimates. The hardware can total a few hundred dollars by itself, before anyone installs it.
- The quotes that skip the permit. The cheapest offers usually do not pull a permit or schedule an inspection. That saves them money and leaves you with an unpermitted electrical change.
What actually moves the price
Inside the $1,197 to $1,497 band, here is what I look at for your specific setup:
- Your panel. Age and available breaker space. A full panel may need a slot freed up first.
- The run. How far the inlet box sits from the panel, and whether the panel is indoors or outdoors.
- 30A vs 50A. Matched to your generator's outlet. The 50A path costs a little more but future-proofs a larger generator.
What you are not paying for
This connects the portable generator you already own to power your selected essential circuits through your panel, the fridge, the furnace blower, the well pump, some lights, the internet. It is not a whole-home standby system and it is not a Generac. If a standby unit is the better fit for you, we will say so.
Want your exact number? It takes about 30 seconds. Read the full inlet and interlock guide, or get your price below.