Portable Generator Hookups

Why You Need a Real Hookup (and Why Extension Cords Don't Cut It)

When the power goes out, most people start running heavy-duty extension cords from the generator into the house — one for the fridge, one for the freezer, one for a space heater, one for the router. It works, sort of, until you realize:

You can't power anything that's hardwired. Your furnace, well pump, electric water heater, and most HVAC systems don't have plugs. Without a real hookup, those stay off — even if the generator could easily run them.
Cord runs create trip hazards and fire risk. Doors don't close properly, cords get pinched, and undersized cords overheat under load.
Some homeowners try to "suicide cord" it. Plugging a generator into a wall outlet through a male-to-male cord is the most dangerous thing you can do in a power outage. It backfeeds the utility lines, exposing utility workers to the full generator voltage stepped up by the transformer. It's illegal, it's deadly, and it's been the cause of multiple lineman fatalities.
A proper hookup makes outages predictable. One generator, one cord, one switch. The right circuits come on. The rest stay off. No improvising in the dark.

Two Code-Compliant Hookup Methods

For portable generators in residential applications, the NEC permits two main approaches. Both are safe, both are common, and which one is right for you depends on your panel, your generator, and what you want to be able to run.

Generator interlock kit — A mechanical plate that bolts onto your existing main panel. It physically prevents the main breaker and the generator backfeed breaker from being on at the same time. You install a dedicated generator breaker in the panel, an inlet box outside, and a flexible cord connecting them. To use it: kill the main breaker, slide the interlock, flip on the generator breaker, start the generator. The whole panel is now powered through the generator, and you manage load by turning circuits on and off at the panel. Lowest cost, most flexibility, requires the interlock kit be listed and matched to your specific panel brand and model.
Manual transfer switch (MTS) — A separate switch box installed next to the main panel, with 6, 8, 10, or more pre-selected critical circuits permanently routed through it. When the power goes out, you flip each transfer switch from "utility" to "generator" individually. Higher cost than an interlock, less flexibility (you can only power the circuits routed through the MTS), but more foolproof for users who'd rather not think about load management. The classic choice for setups where you want to be sure exactly what's powered.

What Gets Installed in a Proper Hookup

A code-compliant portable generator hookup includes:

Inlet box — A weatherproof exterior box (typically NEMA 3R or better) with a male generator inlet on the outside, mounted in a location where the generator can run safely (well-ventilated, away from windows and doors — CDC recommends at least 20 feet from any opening to prevent CO poisoning).
Inlet receptacle type matched to the generator — Typically L14-30 (30A, 7,200W max) or L14-30P/CS6375 (50A, 12,500W max) for the most common portable generator sizes.
Properly sized cable from inlet to panel — 10 AWG for 30A, 6 AWG for 50A, larger for long runs to manage voltage drop.
Interlock kit OR manual transfer switch — Listed and approved for your specific panel brand. Generic interlock kits not listed for your panel will fail inspection.
Generator backfeed breaker — A 2-pole breaker in the panel sized to match the inlet (30A or 50A).
Required signage at the service entrance per NEC 702.7 — indicates that the building has an optional standby system and where the disconnects are.
Permit and inspection — Required in Wake County.

Sizing — How Big a Generator Do You Need?

Most homeowners overbuy or underbuy. The right size depends on what you actually want to run during an outage, not the brochure spec. A few common scenarios:

3,000–5,000 watt generator — Refrigerator, a few lights, modem/router, phone chargers, small space heater. Won't run a central AC, well pump, or electric water heater simultaneously.
5,000–7,500 watt generator — Everything above plus a well pump (if you have one), gas furnace fan, microwave, and limited cooking. Will not run central AC of any meaningful size or an electric water heater.
7,500–10,000 watt generator — Most of the house, including a small central AC unit (if you're careful about other loads) or an electric water heater (one at a time). The sweet spot for most Wake County homes with gas heat.
10,000+ watt generator — Closer to whole-house capability. Can usually run central AC and other major loads, but at this size most homeowners are better off with a permanently installed standby generator with an automatic transfer switch instead of a portable.

Code Compliance — What Matters on a Generator Hookup

North Carolina enforces the 2017 NEC (with NC amendments) for one- and two-family dwellings. Portable generator hookups primarily fall under Article 702 (Optional Standby Systems) and Article 445 (Generators):

NEC 702.5 — Transfer equipment. Transfer equipment is required, and it must be designed to prevent inadvertent parallel operation of the generator and the utility. This is what the interlock kit or manual transfer switch does — it makes simultaneous connection physically impossible.
NEC 702.7 — Signs. A sign at the service equipment must indicate the type and location of on-site optional standby power sources. A sign at the generator inlet must indicate the type of system. Easy to skip, frequently flagged on inspection.
NEC 702.12 — Outdoor source connections. Portable generators connected via a permanently installed inlet have specific requirements for the inlet and disconnect arrangement, especially for higher-amperage inlets (100A+ require an interlocked disconnect).
NEC Article 445 — Generators. Covers generator location, grounding, and connection requirements. The frame of a UL-listed portable generator is bonded to the generator's grounded (neutral) conductor — important when deciding whether the system is a separately derived system or not.
NEC 250 — Grounding and bonding. A portable generator connected through a transfer switch that does not switch the neutral is not a separately derived system, and the neutral must remain bonded only at the service. A transfer switch that does switch the neutral makes the generator a separately derived system, requiring a grounding electrode at the generator. We confirm the right configuration based on your specific setup.
NEC 210.8 — GFCI protection. The new outdoor receptacle for the inlet box itself is subject to GFCI rules for outdoor locations under NC amendments.

Portable vs. Permanent Standby Generator — Which Should You Get?

Portable generators are flexible, affordable, and require you to be home (and willing to go outside) to start them. Permanent standby generators are more expensive but turn on automatically and run the whole house.

Get a portable + hookup if: Outages are infrequent (a few times per year), you're usually home when they happen, you want to spend $500–$2,000 on a generator instead of $8,000–$15,000 on a full system, and you're OK with manual operation.
Get a permanent standby generator if: Outages are frequent, long, or you travel often. You have someone who depends on uninterrupted power (medical equipment, well pump, sump pump in a wet basement). You want the system to start on its own within seconds of losing utility power and run the whole house automatically.

Our Process

1. Walkthrough and load discussion — We look at your panel, your existing generator (or recommend one), and what you want to be able to run during an outage. We make a list of priority circuits.

2. Written estimate — Itemized scope: inlet box, cable, interlock kit or manual transfer switch, breaker, signage, permit, inspection.

3. Permit — Wake County requires a permit for any generator hookup. We handle it.

4. Installation — Most installs are completed in one day. Power is typically off for 1–2 hours during the panel work.

5. Test and demo — We test the hookup end-to-end with your generator, walk you through exactly how to use it during the next outage, and label the panel so you don't have to figure it out at 11pm in the dark.

6. Final inspection — We meet the inspector and confirm the install passes.

FAQ

Frequently Asked Questions

How much does a portable generator hookup cost?

Cost depends on which method you choose (interlock kit vs. manual transfer switch), the size of the inlet (30A vs. 50A), distance from the inlet to the panel, and whether your panel can accept an interlock kit (some older panels can't). An interlock-based hookup is typically the most affordable option. A multi-circuit manual transfer switch costs more in equipment and labor. We provide a written estimate after a walkthrough.

Can I plug my generator into a regular wall outlet?

No — and please don't try. Using a male-to-male "suicide cord" to backfeed an outlet is illegal, deadly, and has killed utility workers responding to power outages. It also has no overcurrent protection, no main breaker isolation, and no listing for that use. The only safe way to connect a portable generator to your house wiring is through a proper inlet box and either an interlock kit or a manual transfer switch.

What's the difference between an interlock kit and a transfer switch?

An interlock kit is a mechanical plate that bolts to your existing main panel and prevents the main breaker and a generator backfeed breaker from being on at the same time. It's cheaper and lets you power any circuit in your panel — you manage load manually. A manual transfer switch is a separate box that permanently routes specific pre-selected circuits through it. It's more expensive but more foolproof: each circuit has its own utility/generator switch.

Do I need a permit to install a generator hookup?

Yes. Any modification to your service panel — including adding a generator inlet, interlock kit, or transfer switch — requires a permit and inspection in Wake County. We handle the permit and meet the inspector on site.

How long does it take to install a generator hookup?

Most residential generator hookups are completed in one day. The on-site work typically takes 4–6 hours, with the power off for 1–2 hours during the panel work. From estimate to final inspection usually runs 1–3 weeks due to permit scheduling.

Can you install a transfer switch for the generator I already have?

Yes — most of our generator hookups are for a generator the homeowner already owns. We confirm the generator's output receptacle (typically L14-30 or L14-30P/CS6375), match the inlet box and cable to it, and size everything to the generator's rated output.

Can a portable generator run my central AC?

Only if it's large enough — typically 7,500 watts minimum for a small central AC unit, and 10,000+ watts for anything substantial. AC compressors have high startup current (LRA, or locked rotor amps) that's 4–7x the running current. We help you size the generator to your actual loads or tell you when central AC just isn't realistic on a portable.

What size cable do I need from the inlet to the panel?

10 AWG for a 30A inlet, 6 AWG for a 50A inlet on a short run. Longer runs require larger conductors to manage voltage drop — the longer the run, the bigger the wire. We size this based on the distance from the inlet location to the panel.

Should I get a portable generator or a whole-house standby generator?

Depends on how often you lose power, how long outages last, whether you're typically home, and your budget. Portable + hookup is $500–$3,000 all-in. Whole-house standby with automatic transfer switch is $8,000–$15,000+. If outages are rare and you're home, portable is fine. If you have medical needs, frequent outages, or travel often, a permanent standby system is the better investment.